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 CUET(UG) 2025

BIOLOGY

20 PRACTICE PAPERS with Full Explanation

As per Syllabus released by NTA

NODIA AND COMPANY

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CUET (UG) Biology 20 Sets
Edition March 2025
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 Contents
PRACTICE PAPER 01 7

PRACTICE PAPER 02 17

PRACTICE PAPER 03 27

PRACTICE PAPER 04 37

PRACTICE PAPER 05 46

PRACTICE PAPER 06 57

PRACTICE PAPER 07 68

PRACTICE PAPER 08 77

PRACTICE PAPER 09 86

PRACTICE PAPER 10 96

PRACTICE PAPER 11 106

PRACTICE PAPER 12 116

PRACTICE PAPER 13 126

PRACTICE PAPER 14 136

PRACTICE PAPER 15 146

PRACTICE PAPER 16 156

PRACTICE PAPER 17 165

PRACTICE PAPER 18 175

PRACTICE PAPER 19 184

PRACTICE PAPER 20 194

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 CUET (UG) Exam - 2025
Syllabus
Biology/Biological
Unit-I Reproduction
• Chapter-1 : Sexual Reproduction in Flowering Plants Flower structure; development of
male and female gametophytes; pollination - types, agencies and examples; out breeding
devices; pollen-pistil interaction; double fertilization; post fertilization events - devel-
opment of endosperm and embryo, development of seed and formation of fruit; special
modes- apomixis, parthenocarpy, polyembryony; Significance of seed dispersal and fruit
formation.
• Chapter-2 : Human Reproduction Male and female reproductive systems; microscopic
anatomy of testis and ovary; gametogenesis -spermatogenesis and oogenesis; menstrual
cycle; fertilisation, embryo development upto blastocyst formation, implantation; preg-
nancy and placenta formation (elementary idea); parturition (elementary idea); lactation
(elementary idea).
• Chapter-3 : Reproductive Health Need for reproductive health and prevention of Sexually
Transmitted Diseases (STDs); birth control - need and methods, contraception and med-
ical termination of pregnancy (MTP); amniocentesis; infertility and assisted reproductive
technologies - IVF, ZIFT, GIFT (elementary idea for general awareness).
Unit-II Genetics and Evolution
• Chapter-4 : Principles of Inheritance and Variation Heredity and variation : Mendelian
inheritance; deviations fromMendelism – incomplete dominance, co-dominance, multi-
ple alleles and inheritance of blood groups, pleiotropy;elementary idea of polygenic in-
heritance; chromosome theory of inheritance; chromosomes and genes; Sexdetermina-
tion - in humans, birds and honey bee; linkage and crossing over; sex linked inheritance
- haemophilia,colour blindness; Mendelian disorders in humans - thalassemia; chromo-
somal disorders in humans; Down’ssyndrome, Turner’s and Klinefelter’s syndromes.
• Chapter-5 : Molecular Basis of Inheritance Search for genetic material and DNA as genet-
ic material; Structure of DNA and RNA; DNA packaging; DNA replication; Central Dog-
ma; transcription, genetic code, translation; geneexpression and regulation - lac operon;
Genome, Human and rice genome projects; DNA fingerprinting.
• Chapter-6 : Evolution Origin of life; biological evolution and evidences for biological evo-
lution (paleontology,comparative anatomy, embryology and molecular evidences); Dar-
win’s contribution, modern synthetic theory ofevolution; mechanism of evolution - vari-
ation (mutation and recombination) and natural selection with examples,types of natural
selection; Gene flow and genetic drift; Hardy- Weinberg’s principle; adaptive radiation;
human evolution.
Unit-III : Biology and Human Welfare
• Chapter-7 : Human Health and Disease Pathogens; parasites causing human diseases
(malaria, dengue, chikungunya, filariasis, ascariasis, typhoid, pneumonia, common cold,
amoebiasis, ring worm) and their control; Basic concepts of immunology - vaccines; can-
cer, HIV and AIDS; Adolescence - drug and alcohol abuse.

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 • Chapter-8 : Microbes in Human Welfare Microbes in food processing, industrial pro-
duction, sewage treatment, energy generation and microbes as bio-control agents and
bio-fertilizers. Antibiotics; production and judicioususe.

Unit-IV Biotechnology and its Applications

• Chapter-9 : Biotechnology : Principles and Processes Genetic Engineering (Recombinant
DNA Technology).
• Chapter-10 : Biotechnology and its Applications Application of biotechnology in health
and agriculture : Human insulin and vaccine production, stem cell technology, gene ther-
apy; genetically modified organisms - Bt crops; transgenic animals; biosafety issues, bi-
opiracy and patents.
Unit-V Ecology and Environment
• Chapter-11 : Organisms and Populations Population interactions - mutualism, competi-
tion, predation, parasitism; population attributes - growth, birth rate and death rate, age
distribution. (Topics excluded : Organism and its Environment, Major Aboitic Factors,
Responses to Abioitic Factors, Adaptations)
• Chapter-12 : Ecosystem Ecosystems : Patterns, components; productivity and decompo-
sition; energy flow; pyramids of number, biomass, energy (Topics excluded : Ecological
Succession and Nutrient Cycles).
• Chapter-13 : Biodiversity and Conservation Biodiversity-Concept, patterns, importance;
loss of biodiversity;biodiversity conservation; hotspots, endangered organisms, extinc-
tion, Red Data Book, Sacred Groves, biosphere reserves, national parks, wildlife, sanctu-
aries and Ramsar sites.

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 PRACTICE PAPER 01

PRACTICE PAPER 01

1. What is the term for the transfer of pollen grains from Heterostyly is a floral adaptation where flowers exhibit
the anther to the stigma of a flower? different stigma and anther heights, reducing self-
(A) Fertilization pollination. By forcing visiting pollinators to contact
(B) Pollination anthers and stigmas at varying levels, this arrangement
(C) Parthenocarpy enhances cross-pollination efficiency. It preserves
(D) Syngamy genetic diversity, ensuring healthier progeny and


Ans contributing to the species’ long-term evolutionary
success in diverse habitats.
(B) Pollination
Pollination is the process in which pollen grains move 4. What is spermatogenesis?
from a flower’s anther to its stigma, enabling fertilization. (A) Fusion of egg and sperm
This fundamental event precedes the fusion of male and (B) Formation of breast milk
female gametes. It can occur via wind, water, or living (C) Process of sperm production
organisms, ensuring genetic exchange and successful (D) Development of mature follicles
seed formation in flowering plants.

Ans
2. Which of the following structures develops into a fruit (C) Process of sperm production
after fertilization in angiosperms? Spermatogenesis is the process of sperm cell
(A) Ovary formation in the testes. It involves mitotic divisions of
(B) Ovule spermatogonia, meiotic divisions producing haploid
(C) Anther spermatids, and their maturation into functional
(D) Stigma sperm. Hormonal regulation by the pituitary and testes


Ans ensures continuous production of millions of sperm
each day, crucial for successful fertilization in human
(A) Ovary reproduction.
The ovary matures into the fruit following fertilization,
while each fertilized ovule forms a seed. This 5. In humans, the site of fertilization is usually the...
transformation protects developing seeds and aids in (A) Cervix
their dispersal. Angiosperm fruits vary significantly (B) Uterus
in structure, reflecting specialized adaptations that (C) Fallopian tube
facilitate germination, ensure survival of offspring, (D) Vagina
and perpetuate the plant life cycle across diverse

Ans
environments.
(C) Fallopian tube
3. Which phenomenon prevents self-pollination in some In humans, fertilization ordinarily occurs in the
bisexual flowers by physically separating anthers and ampullary-isthmic region of the fallopian tube. After
stigma? ovulation, the secondary oocyte is picked up by the
(A) Protogyny fimbriae and transported there, where sperm meet the
(B) Protandry egg, leading to formation of the zygote. This location
(C) Heterostyly provides optimal conditions for successful fusion and
(D) Geitonogamy initial embryonic development.


Ans 6. Which of the following is NOT a function of the placenta
(C) Heterostyly during human pregnancy?
(A) Exchange of gases

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page 8 CUET UG Biology

(B) Hormone secretion (D) Oogenesis

(C) Nutrient supply

Ans
(D) Production of sperms
(D) Oogenesis


Ans IVF (In Vitro Fertilization), GIFT (Gamete Intrafallopian
(D) Production of sperms Transfer), and ZIFT (Zygote Intrafallopian Transfer) are
The placenta facilitates nutrient transport, gas exchange, forms of assisted reproductive technologies, used to
and waste removal for the developing fetus. It also address infertility. Oogenesis is the natural development
secretes essential hormones like human chorionic of ova in the female ovary, a normal biological process,
gonadotropin, progesterone, and estrogens. However, it not a medical intervention designed to facilitate
does not produce sperm, which form in the male testes conception or overcome infertility issues.
through spermatogenesis, a process entirely unrelated
10. What is the phenotypic ratio typically observed in the
to placental functions or fetal development.
F2 generation of a Mendelian monohybrid cross?
7. Which of the following is a sexually transmitted disease (A) 2:1
caused by a bacterium? (B) 3:1
(A) HIV/AIDS (C) 9:3:3:1
(B) Genital herpes (D) 1:1
(C) Syphilis

Ans
(D) Hepatitis B
(B) 3:1


Ans In Mendelian monohybrid crosses involving a single
(C) Syphilis gene with two alleles, the F2 generation typically
Syphilis is caused by the bacterium Treponema pallidum, displays a 3:1 phenotypic ratio (dominant to recessive).
transmitted primarily through sexual contact. Early This arises because each trait segregates independently
symptoms often include painless sores, but infection can during gamete formation, allowing the recessive
progress to severe complications if untreated. Diagnosis phenotype to reappear in one quarter of the offspring
is typically through blood tests, and penicillin-based while three-quarters display the dominant phenotype.
treatments are effective. Maintaining safe sexual
11. In snapdragon plants showing incomplete dominance,
practices is crucial for preventing this bacterial disease.
crossing a red-flowered plant (RR) with a white-flowered
8. Which term refers to the intentional termination of plant (rr) produces offspring with ______ flowers.
pregnancy before full term? (A) Red
(A) Infertility (B) White
(B) Menopause (C) Pink
(C) Amniocentesis (D) Yellow
(D) Medical Termination of Pregnancy

Ans


Ans (C) Pink
(D) Medical Termination of Pregnancy In snapdragons, incomplete dominance results when
Medical Termination of Pregnancy (MTP) denotes neither allele completely masks the other. Crossing
a deliberate intervention to end a pregnancy before it homozygous red (RR) and homozygous white (rr) plants
can result in a viable birth. It may be recommended for yields F1 hybrids with pink flowers. Each allele partially
various medical, genetic, or social reasons. Stringent influences flower color, leading to an intermediate
regulations and medical oversight aim to reduce phenotype that exhibits a blend of parental traits rather
associated risks and ensure safe, controlled conditions than clear dominance in their expression.
for the procedure.
12. Which of the following disorders is NOT inherited as a
9. Which of the following is NOT an assisted reproductive Mendelian recessive trait?
technology? (A) Cystic fibrosis
(A) IVF (B) Thalassemia
(B) GIFT (C) Haemophilia
(C) ZIFT (D) Turner’s syndrome

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 PRACTICE PAPER 01

Ans (C) Translation

(D) Turner’s syndrome Translation is the biological process in which the
Cystic fibrosis, thalassemia, and haemophilia can follow ribosome reads the mRNA codons and assembles a
recessive inheritance patterns. In contrast, Turner’s corresponding polypeptide chain. Transfer RNAs carry
syndrome (45,X) arises from a chromosomal anomaly specific amino acids to the ribosome, matching their
where an individual has only one X chromosome. This anticodons to the mRNA codons. This ensures that the
condition does not stem from a single-gene recessive genetic information encoded in mRNA is converted
trait but from the loss of an entire sex chromosome into a functional protein product.
during gamete formation.
16. Which theory proposes that evolution occurs through
13. What is a codon? small, gradual changes accumulating over long periods?
(A) A unit of replication (A) Punctuated equilibrium
(B) A three-nucleotide sequence on mRNA (B) Natural selection
(C) A protein subunit (C) Modern synthetic theory
(D) A polymerase enzyme (D) Lamarckism


Ans

Ans
(B) A three-nucleotide sequence on mRNA (C) Modern synthetic theory
A codon is a triplet of nucleotides on messenger RNA The modern synthetic theory integrates Darwin’s
that specifies a particular amino acid or termination concept of natural selection with genetics, stating
signal during protein synthesis. Ribosomes read codons that small genetic changes accumulate gradually
in sequence, translating each into the correct amino in populations over many generations. This steady
acid. This universal genetic code underpins the faithful accumulation of heritable variations, together with
conversion of genetic information into functional selection and other factors like genetic drift, drives
proteins in organisms. evolutionary change. It provides a unifying framework
for understanding biodiversity’s origins.
14. Which enzyme is primarily responsible for unwinding
the DNA helix during replication? 17. Which of the following is a common example of adaptive
(A) RNA polymerase radiation?
(B) DNA gyrase (A) Human evolution in Africa
(C) Helicase (B) Finches on the Galápagos Islands
(D) DNA ligase (C) Cacti in deserts
(D) Bacterial mutation in labs


Ans


Ans
(C) Helicase
During DNA replication, helicase unwinds the double (B) Finches on the Galápagos Islands
helix by breaking the hydrogen bonds between Darwin’s finches in the Galápagos Islands exemplify
complementary bases. This separation creates two adaptive radiation, where ancestral species diversified
single-stranded templates for DNA polymerase to copy. into multiple forms, each adapted to a distinct ecological
Helicase activity is essential for forming the replication niche. Differences in beak shape reflect specialized
fork, ensuring that each original strand is accessible feeding habits, demonstrating how natural selection can
for accurate and efficient DNA synthesis throughout S drive evolutionary branching. This process showcases
phase. the role of geographic isolation in promoting species
diversity.
15. Which process describes the synthesis of a polypeptide
chain from an mRNA template? 18. Which mechanism of evolution relies primarily on
(A) Replication random changes in allele frequencies, contrasting with
(B) Transcription natural selection’s non-random nature?
(C) Translation (A) Gene flow
(D) Transformation (B) Genetic drift
(C) Mutation


Ans
(D) Recombination

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page 10 CUET UG Biology

Ans Biofertilizers are preparations containing living

(B) Genetic drift microorganisms, such as nitrogen-fixing bacteria or
Genetic drift is a random fluctuation in allele frequencies phosphate-solubilizing fungi, that boost soil fertility and
within small populations, independent of trait plant growth. They work symbiotically or sustainably
advantage. In contrast, natural selection is non-random, in the soil, enhancing nutrient availability and uptake
favoring alleles that enhance survival or reproduction. by plants. Unlike chemical fertilizers, biofertilizers are
Genetic drift can lead to the fixation or loss of alleles eco-friendly and reduce dependency on nonrenewable
purely by chance, significantly influencing evolutionary resources for crop productivity.
trajectories in isolated groups.
22. Which microbe is commonly used for curd formation
19. Which disease is caused by Plasmodium species and from milk?
transmitted by Anopheles mosquitoes? (A) Saccharomyces cerevisiae
(A) Dengue (B) Rhizobium leguminosarum
(B) Chikungunya (C) Lactobacillus bulgaricus
(C) Malaria (D) Penicillium notatum
(D) Filaria

Ans


Ans (C) Lactobacillus bulgaricus
(C) Malaria Lactobacillus bulgaricus, along with Streptococcus
Malaria is caused by Plasmodium parasites (such as thermophilus, is a key bacterium used to ferment milk
P. vivax, P. falciparum, and P. malariae), transmitted into curd. It converts lactose into lactic acid, which
through the bite of female Anopheles mosquitoes. coagulates milk proteins and imparts the characteristic
The parasite invades red blood cells, causing cyclical sour taste. The controlled microbial action ensures
fevers, chills, and anemia. Prompt diagnosis, protective consistent texture and flavor, making curd a staple dairy
measures, and antimalarial drugs are critical to product worldwide and widely consumed.
controlling and treating this widespread infection.
23. Which of the following microbes is used in the
20. What is a vaccine? commercial production of citric acid?
(A) A natural pathogen (A) Aspergillus niger
(B) A weakened or inactivated pathogen (B) Acetobacter aceti
(C) A type of hormone (C) Penicillium chrysogenum
(D) An antibiotic (D) Clostridium acetobutylicum


Ans

Ans
(B) A weakened or inactivated pathogen (A) Aspergillus niger
A vaccine contains weakened or inactivated pathogens, Aspergillus niger, a fungus, is widely employed in
or subunits thereof, designed to safely trigger an immune industrial processes to produce citric acid. Under
response. This controlled exposure stimulates the body’s controlled fermentation conditions, it metabolizes
production of antibodies and memory cells without sugars and accumulates citric acid in large amounts.
causing full-blown disease. By priming the immune This compound is then extracted and purified for use
system, vaccines confer protection against future in beverages, pharmaceuticals, and other applications,
infections by the targeted pathogen very effectively. making Aspergillus niger essential for commercial citric
acid production.
21. What are biofertilizers?
(A) Chemical compounds that kill pests 24. What is the role of restriction enzymes in recombinant
(B) Living organisms that improve soil fertility DNA technology?
(C) Synthetic nutrients added to crops (A) They synthesize new strands of DNA
(D) Petroleum-based fertilizers (B) They join fragments of DNA
(C) They cut DNA at specific sequences


Ans
(D) They degrade mRNA molecules
(B) Living organisms that improve soil fertility


Ans
(C) They cut DNA at specific sequences

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 PRACTICE PAPER 01

Restriction enzymes, also called molecular scissors, (B) Bt cotton

recognize and cleave DNA at specific nucleotide Bt cotton is genetically modified to express the Cry
sequences known as restriction sites. This precise proteins from Bacillus thuringiensis, toxic to specific
cutting enables scientists to isolate desired genes and insect larvae. The gene encoding this protein is
insert them into vectors. By creating compatible sticky introduced into the cotton plant, allowing it to produce
or blunt ends, restriction enzymes facilitate targeted the insecticidal substance. This significantly reduces
recombination, making them crucial tools in genetic reliance on chemical pesticides and can enhance crop
engineering. yields, benefiting farmers.

25. In polymerase chain reaction (PCR), which enzyme is 28. What is gene therapy primarily intended to do?
responsible for DNA synthesis? (A) Create entirely new organs
(A) T4 DNA ligase (B) Alter an organism’s entire genome
(B) Reverse transcriptase (C) Treat genetic disorders by correcting faulty genes
(C) Taq DNA polymerase (D) Eliminate non-genetic diseases
(D) RNA polymerase

Ans


Ans (C) Treat genetic disorders by correcting faulty genes
(C) Taq DNA polymerase Gene therapy focuses on treating genetic disorders
PCR amplifies specific DNA sequences using Taq DNA by introducing, removing, or correcting defective
polymerase, a heat-stable enzyme derived from Thermus genes. By delivering functional genetic material into a
aquaticus. During repeated cycles of denaturation, patient’s cells, it aims to restore normal protein function
annealing, and extension, Taq polymerase synthesizes or regulate abnormal gene expression. Although still
new DNA strands complementary to the target region. developing, gene therapy holds promise for conditions
Its high temperature tolerance makes it ideal for that completely lack effective conventional treatments.
PCR’s cyclic heating steps, enabling exponential DNA
29. How do Bt crops differ from traditionally bred resistant
replication.
varieties?
26. In genetic engineering, which vector is commonly used (A) Bt crops contain no inserted genes
to introduce foreign DNA into bacteria? (B) Bt crops are non-living solutions
(A) Ribosome (C) Bt crops have a gene from a bacterium
(B) Plasmid (D) Bt crops produce seeds without pollination
(C) Mitochondrion

Ans
(D) Centriole
(C) Bt crops have a gene from a bacterium


Ans Bt crops carry a gene from Bacillus thuringiensis,
(B) Plasmid enabling them to produce insecticidal proteins that
Plasmids are small, circular, extrachromosomal DNA target specific pests. In contrast, traditionally bred
molecules in bacteria frequently used as vectors. resistant varieties rely on the plant’s inherent genetic
They can replicate independently of the bacterial diversity. By expressing the Bt gene, these transgenic
chromosome, carry foreign genes, and facilitate plants directly deter insect damage, reducing the need
their expression. Researchers insert target DNA into for chemical pesticide applications.
plasmids, then transform bacterial cells, enabling the
30. What is predation in ecological terms?
propagation and efficient study and manipulation of the
introduced genetic material. (A) A symbiosis where both species benefit
(B) Interaction in which one species kills and consumes
27. Which genetically modified crop is engineered to another
produce the Bacillus thuringiensis toxin? (C) Relationship where organisms share resources
(A) Golden Rice equally
(B) Bt cotton (D) Mutualism between predator and prey
(C) Flavr Savr tomato

Ans
(D) Roundup Ready soybean
(B) Interaction in which one species kills and consumes


Ans another

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Predation is an ecological interaction in which one (C) Producers always fix energy from sunlight
organism, the predator, hunts, kills, and consumes The energy pyramid rarely inverts because producers fix
another organism, the prey. This dynamic influences energy from the sun, setting an upper limit on energy
population sizes and drives evolutionary adaptations flow. Each subsequent trophic level receives only a
in both predator and prey. By removing weak or sick fraction of that energy, owing to metabolic losses and
individuals, predation can help maintain a balanced incomplete assimilation. Consequently, higher trophic
ecosystem, shaping community structure over time. levels cannot surpass producers in total energy content,
preserving the pyramid shape.
31. In a population growth curve, which phase is marked
by rapid increase in population size due to abundant 34. Which of the following is designated as a biodiversity
resources? hotspot in India?
(A) Lag phase (A) The Indo-Gangetic plains
(B) Exponential phase (B) Thar Desert
(C) Stationary phase (C) Western Ghats
(D) Death phase (D) Sundarbans


Ans

Ans
(B) Exponential phase (C) Western Ghats
The exponential phase features a rapid increase in The Western Ghats is recognized as a biodiversity
population size when resources are abundant and hotspot due to its high species richness and endemism.
environmental conditions are favorable. Each generation Encompassing diverse habitats, from tropical forests
grows proportionally to the current population, leading to grasslands, it hosts numerous endemic plant and
to a steep rise. Eventually, resource limitations or other animal species. However, habitat loss, deforestation,
factors slow growth, marking the transition to the and other human activities threaten its ecological
stationary phase in a typical sigmoidal curve. integrity, necessitating focused conservation efforts and
protections.
32. What is primary productivity in an ecosystem?
(A) Total biomass of consumers 35. Why is the loss of biodiversity a concern for human
(B) Rate at which producers convert light energy to welfare?
chemical energy (A) Loss of biodiversity has no impact on ecosystem
(C) Decomposition of organic matter services
(D) Movement of toxins along trophic levels (B) It only affects exotic species


Ans (C) It may reduce resources, medicines, and ecosystem
resilience
(B) Rate at which producers convert light energy to (D) It ensures complete eradication of invasive species
chemical energy
Primary productivity denotes the rate at which

Ans
autotrophs, primarily photosynthetic organisms, (C) It may reduce resources, medicines, and ecosystem
capture and convert solar energy into chemical energy resilience
(organic compounds). It underpins the entire food web Declining biodiversity threatens ecosystem services
by providing the base energy source. Factors like light such as pollination, water purification, and soil fertility,
intensity, temperature, and nutrient availability can impacting agriculture and resource availability. Many
significantly influence primary productivity in diverse medicines originate from diverse species, and reduced
ecosystems across the globe. genetic variability can limit resilience to environmental
changes. Hence, preserving biodiversity is essential for
33. Why does the energy pyramid never invert in a typical sustaining human livelihoods, health, and ecological
ecosystem? stability over the long term.
(A) Each level gains mass automatically
(B) Energy is recycled without losses 36. Match the terms in Column I with their descriptions in
(C) Producers always fix energy from sunlight Column II:
(D) Highest trophic level has maximum biomass Column I Column II


Ans

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 PRACTICE PAPER 01

1. Zygote transferred to P. GIFT (B) Both A and R are true, but R is not the correct
fallopian tube explanation of A
(C) A is true, but R is false
2. Sperm injected into ovum Q. ZIFT
(D) A is false, but R is true
3. Gametes transferred to R. IVF
fallopian tube

Ans
4. Fertilization in a test tube S. ICSI (C) A is true, but R is false
Options : Smoking is a major risk factor for lung cancer, as
(A) P-3, Q-1, R-4, S-2 carcinogens in tobacco smoke can trigger cellular
(B) P-4, Q-2, R-1, S-3 mutations. However, cancer can result from multiple
(C) P-2, Q-4, R-3, S-1 factors, not exclusively viral infections. Thus, while
(D) P-3, Q-2, R-1, S-4 the assertion is true, the reason is false, indicating that
viruses are merely one among many potential causes of


Ans
malignancies.
(A) P-3, Q-1, R-4, S-2
In GIFT (Gamete Intrafallopian Transfer), gametes 39. Assertion (A) : During transcription in eukaryotes, the
are placed into the fallopian tube (P-3). ZIFT (Zygote initial RNA transcript is longer than the final mRNA.
Intrafallopian Transfer) involves placing a fertilized Reason (R) : Eukaryotic genes often contain introns
zygote into the tube (Q-1). IVF (In Vitro Fertilization) which are removed during RNA processing.
refers to fertilization outside the body (R-4). ICSI (A) Both A and R are true, and R is the correct
(Intracytoplasmic Sperm Injection) entails injecting explanation of A
sperm directly into the egg (S-2), bypassing natural (B) Both A and R are true, but R is not the correct
processes. explanation of A
(C) A is true, but R is false
37. Which combination of statements about DNA (D) A is false, but R is true
replication is correct?


Ans
I. It occurs during the S phase of the cell cycle.
II. It is semiconservative in nature. (A) Both A and R are true, and R is the correct
III. It uses RNA primase to lay down primers. explanation of A
IV. It does not require enzymes. In eukaryotic cells, the primary transcript (pre-mRNA)
(A) I, II, and III are correct includes both exons and introns, making it longer than
(B) II, III, and IV are correct the final mRNA. Introns are subsequently removed
(C) I, III, and IV are correct through splicing, and exons are joined to form the
(D) I, II, and IV are correct mature mRNA. Thus, the reason correctly explains
why the initial RNA transcript exceeds the size of the


Ans
functional message.
(A) I, II, and III are correct
DNA replication takes place in the S phase, is 40. Arrange the following events of fertilization in the
semiconservative (each daughter molecule has one correct chronological order:
parental strand), and requires RNA primers laid down 1. Acrosome reaction
by primase. Critical enzymes like DNA polymerases, 2. Binding of sperm to zona pellucida
helicases, and ligases are also involved. Consequently, 3. Fusion of sperm and egg membranes
statement IV is incorrect because replication cannot 4. Cortical reaction
occur without enzymatic assistance and regulatory (A) 1 → 2 → 4 → 3
factors. (B) 2 → 1 → 3 → 4
(C) 2 → 1 → 4 → 3
38. Assertion (A) : Smoking can increase the risk of lung (D) 1 → 2 → 3 → 4
cancer.


Ans
Reason (R) : Cancer is exclusively caused by viral
infections. (C) 2 → 1 → 4 → 3
(A) Both A and R are true, and R is the correct The sperm first binds to the zona pellucida (2), triggering
explanation of A the acrosome reaction (1) that releases enzymes. Next,

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page 14 CUET UG Biology

the cortical reaction (4) occurs in the egg to prevent

Ans

polyspermy. Finally, the sperm and egg membranes fuse (C) Facilitate reproductive success
(3), allowing the sperm nucleus to enter and complete The case study notes that a variety of pollinators, such
fertilization successfully in many species. as bees and birds, helps ensure efficient pollen transfer
among flowers. Greater diversity reduces reliance


Direction :Carefully read the case study provided and then
on any single pollinator and increases the chance of
thoroughly answer the subsequent five questions.
successful outcrossing. This promotes higher seed set,
The pollination process in flowering plants involves
genetic variability, and overall reproductive success in
intricate relationships between the plant and its pollinators.
plant populations.
Consider a region where multiple flowering species
coexist, each displaying unique floral characteristics such 43. How does climate change exacerbate pollination
as color, shape, and nectar rewards. Bees, butterflies, and challenges in the described ecosystem?
birds visit these flowers, transferring pollen as they forage (A) By synchronizing flowering with pollinator activity
for food. However, habitat fragmentation and declining (B) By lengthening pollinators’ foraging season
pollinator populations threaten these interactions, leading (C) By creating temporal mismatches in flowering
to reduced cross-pollination and lower seed set. Scientists times
studying this ecosystem observe that diverse pollinator (D) By uniformly increasing plant diversity
communities enhance reproductive success by promoting


Ans
outbreeding. Conservation measures like preserving
natural habitats and planting pollinator-friendly species (C) By creating temporal mismatches in flowering times
are being proposed to stabilize pollination networks The case study highlights that shifts in climate patterns
and maintain plant diversity. Understanding these can alter flowering schedules, potentially causing
relationships is crucial for sustaining vibrant ecosystems pollinators to miss peak bloom periods. If pollinators are
and agricultural productivity. Additionally, changes not present when flowers are receptive, fertilization rates
in climate patterns can shift flowering times, creating drop. Such temporal mismatches weaken pollination
temporal mismatches with pollinator activity. effectiveness and can reduce seed production,
threatening the stability of plant populations.
41. Which factor mentioned in the study primarily threatens
pollination services? 44. What is one key conservation proposal mentioned in
(A) Natural breeding barriers the study?
(B) Habitat fragmentation (A) Constructing artificial pollinator robots
(C) Increased pollinator diversity (B) Removing all nectar-producing plants
(D) Accelerated seed set (C) Preserving natural habitats
(D) Importing non-native pollinators


Ans


Ans
(B) Habitat fragmentation
Habitat fragmentation breaks continuous landscapes (C) Preserving natural habitats
into isolated patches, limiting pollinator movement The study suggests preserving natural habitats and
and reducing cross-pollination. This fragmentation can planting pollinator-friendly species to bolster pollinator
disrupt mutualistic relationships between plants and populations. Intact habitats support diverse flora and
their pollinators, potentially decreasing reproductive fauna, stabilizing essential interactions like pollination.
success. When pollinators cannot traverse fragmented By protecting these areas, pollinators have continuous
habitats, fewer flowers are pollinated, significantly foraging resources and nesting sites, improving their
diminishing seed production and overall ecosystem survival and ensuring that the mutual benefits between
resilience and long-term stability. plants and pollinators persist.

42. What role do diverse pollinator communities play 45. Which statement best summarizes the relationship
according to the case study? between pollinators and flowering plants?
(A) Restrict outbreeding (A) Pollinators seldom affect seed production
(B) Promote habitat fragmentation (B) Both parties benefit through food and reproduction
(C) Facilitate reproductive success (C) Plants provide no reward to pollinators
(D) Eliminate native plant species (D) Pollinators only harm plant fitness

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 PRACTICE PAPER 01

Ans (B) Widespread use of prenatal diagnosis

(B) Both parties benefit through food and reproduction (C) Consanguineous marriages
Pollinators gain nectar or pollen as a nutritional resource, (D) Balanced diet adoption
while flowering plants achieve cross-pollination and

Ans
subsequent seed production. This mutualism underpins
(C) Consanguineous marriages
ecosystem stability, as both groups rely on each other
Consanguineous marriages increase the likelihood that
for survival. Disruptions to pollinator populations
both partners carry the same recessive gene mutation,
directly affect plant reproduction, illustrating the
severely elevating the risk of passing Thalassemia to
interdependence critical for sustaining biodiversity and
offspring. When close relatives have shared ancestry,
food webs.
genetic variants become more concentrated, amplifying


Direction :Carefully read the case study provided and then the probability that children inherit defective alleles
thoroughly answer the subsequent five questions. from each parent, leading to higher disease incidence.
A rural community exhibits a high occurrence of
48. Which medical intervention helps remove excess iron
Thalassemia, a hereditary blood disorder. Medical
accumulated from frequent blood transfusions?
practitioners observe children presenting with severe
(A) Antibiotic regimen
anemia, growth delays, and skeletal deformities.
(B) Immunosuppressants
Laboratory tests confirm impaired hemoglobin synthesis
(C) Iron chelation therapy
due to mutations in genes coding for hemoglobin’s alpha
(D) Hormone replacement
or beta chains. Limited awareness and consanguineous
marriages within the community exacerbate disease

Ans
transmission, raising concerns about the genetic counseling (C) Iron chelation therapy
needed. Healthcare workers implement awareness Repeated blood transfusions introduce additional iron
campaigns stressing carrier testing, prenatal diagnosis, into the body, which can deposit in vital organs and
and early interventions. They also advocate balanced cause damage over time. Iron chelation therapy employs
diets, regular blood transfusions, and iron chelation agents that bind surplus iron, allowing its excretion
therapy where needed. These measures aim to improve through urine or feces. This treatment is critical in
patient quality of life and reduce future incidence rates. Thalassemia management, preventing complications
The response underscores how education and medical arising from iron overload in transfusion-dependent
support can mitigate the effects of inherited disorders. patients.
Genetic testing facilities remain limited, underscoring the
need for expanded healthcare infrastructure. 49. How do healthcare workers aim to reduce Thalassemia
incidence in the described community?
46. What fundamental genetic defect underlies Thalassemia? (A) By discouraging carrier testing
(A) Abnormal plasma membrane (B) By abolishing blood banks
(B) Disruption in carbohydrate metabolism (C) Through genetic counseling and prenatal diagnosis
(C) Faulty hemoglobin chain synthesis (D) By increasing consanguineous marriages
(D) Excessive RBC lifespan


Ans


Ans
(C) Through genetic counseling and prenatal diagnosis
(C) Faulty hemoglobin chain synthesis The case study indicates that healthcare workers
Thalassemia results from mutations in genes that code promote carrier testing to identify at-risk couples and
for the alpha or beta globin chains of hemoglobin. These recommend prenatal diagnosis to detect affected fetuses
defects reduce or eliminate the production of functional early. By offering genetic counseling, they guide families
hemoglobin subunits, leading to impaired oxygen toward informed reproductive choices. These measures
transport. The condition manifests as severe anemia and collectively aim to lower disease frequency and lessen
related complications due to dysfunctional red blood the impact of Thalassemia on future generations.
cells in affected individuals.
50. What key challenge limits the effectiveness of
47. Which factor in the community contributes to higher Thalassemia management in this region?
transmission of Thalassemia? (A) Lack of any hereditary factors
(A) Access to genetic counseling (B) Well-established genetic testing centers

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(C) Limited healthcare infrastructure

(D) Total elimination of awareness campaigns


Ans
(C) Limited healthcare infrastructure
According to the case study, the region faces insufficient
genetic testing facilities and broader healthcare
infrastructure constraints. Without readily accessible
diagnostic tools and medical support, early detection
and ongoing treatment become difficult. Enhancing
healthcare capacity is vital for comprehensive
management, preventing complications, and improving
the overall prognosis for Thalassemia patients.

*************

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 PRACTICE PAPER 02

PRACTICE PAPER 02

1. What does the term “double fertilization” in angiosperms Parthenocarpy is the development of fruit without
refer to? fertilization, leading to seedless varieties. Auxin can
(A) Fertilization of two eggs by a single sperm be applied externally to trigger fruit formation in the
(B) Fusion of one sperm with the egg and another absence of pollination or fertilization. Commercial
sperm with the polar nuclei growers exploit this method to produce seedless fruits,
(C) Simultaneous fertilization of two separate ovules which are often preferred by consumers for their
(D) Fusion of two pollen grains with the same ovule convenience and taste.


Ans 4. Which term describes the onset of menstruation in
(B) Fusion of one sperm with the egg and another sperm human females?
with the polar nuclei (A) Menopause
Double fertilization in flowering plants involves one (B) Menarche
sperm fusing with the egg to form a zygote, while the (C) Ovulation
other sperm fuses with the two polar nuclei to create (D) Parturition
the triploid endosperm. This unique process ensures

Ans
simultaneous development of both embryo and
nutrient-rich tissue necessary for seedling growth. (B) Menarche
Menarche is the first occurrence of menstrual bleeding
2. Which of the following structures in a seed develops in a human female, signaling the onset of reproductive
into the shoot system? capability. This event usually happens during puberty,
(A) Radicle around ages 11–14. Menopause marks the end of
(B) Plumule menstrual cycles later in life, ovulation releases a mature
(C) Testa ovum, and parturition is the process of childbirth.
(D) Scutellum
5. Which extra-embryonic membrane in humans


Ans primarily forms the placenta?
(B) Plumule (A) Amnion
The plumule is the part of the embryo that gives rise (B) Chorion
to the shoot system, including stems and leaves. Upon (C) Allantois
germination, it grows upward, while the radicle forms (D) Yolk sac
the root system. The seed coat (testa) protects the

Ans
embryo, and in monocots like maize, the scutellum aids
in nutrient transfer. (B) Chorion
The chorion is a key extra-embryonic membrane in
3. In many plants, parthenocarpy results in seedless fruits. humans that, along with maternal tissue, contributes
Which hormone is often artificially applied to induce to placenta formation. The placenta supports fetal
this effect? development by facilitating nutrient uptake, waste
(A) Ethylene elimination, and gas exchange. Other membranes—
(B) Auxin amnion, allantois, and yolk sac—have distinct roles but
(C) Cytokinin are less directly involved in placental structure.
(D) Abscisic acid
6. What triggers the start of labour contractions in human


Ans parturition?
(B) Auxin (A) Sudden decrease in fetal movements
(B) Release of oxytocin

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(C) Complete absence of progesterone

Ans

(D) Closure of the cervix (C) Ringworm


Ans Ringworm is a common fungal infection of the skin,
typically spread through direct contact or contaminated
(B) Release of oxytocin
surfaces. It is not classified as an STD. In contrast,
Oxytocin from the posterior pituitary initiates and
chlamydia, gonorrhea, and trichomoniasis are sexually
sustains uterine contractions during childbirth. It acts on
transmitted infections that affect the reproductive tract,
the uterine muscles, causing rhythmic contractions that
requiring proper diagnosis and treatment to prevent
help dilate the cervix and push the fetus out. Although
complications.
progesterone levels decline, the direct hormonal trigger
driving labour contractions is primarily the surge in 10. How many copies of each gene are typically present in
oxytocin. a diploid cell?
(A) 1
7. Which of the following is used to detect genetic
(B) 2
abnormalities in a fetus by sampling amniotic fluid?
(C) 3
(A) Tubectomy
(D) 4
(B) Castration
(C) Amniocentesis

Ans
(D) Colostrum test (B) 2


Ans In diploid organisms, cells contain two copies
(alleles) of each gene—one from each parent. These
(C) Amniocentesis
homologous chromosomes carry corresponding gene
Amniocentesis is a prenatal diagnostic procedure where
loci, permitting dominant, recessive, co-dominant, or
a small amount of amniotic fluid is withdrawn and
other inheritance patterns. During meiosis, these alleles
examined for chromosomal or genetic disorders in the
segregate, ensuring offspring inherit a mix of genetic
fetus. This fluid contains fetal cells and biochemical
material from both paternal and maternal lines.
substances. Early detection helps parents make
informed decisions, although the procedure carries a 11. In a dihybrid cross with two independently assorting
slight risk of miscarriage. traits, what phenotypic ratio is expected in the F2
generation?
8. Which contraceptive method involves the surgical
(A) 1:1:1:1
removal of a small segment of each vas deferens?
(B) 9:3:3:1
(A) Vasectomy
(C) 3:1
(B) Tubal ligation
(D) 2:2
(C) Condom use
(D) Oral pills

Ans

Ans (B) 9:3:3:1

For two genes that assort independently, Mendelian
(A) Vasectomy
dihybrid crosses produce an F2 generation with a 9:3:3:1
Vasectomy is a permanent sterilization procedure for
phenotypic ratio. Nine offspring show both dominant
males, involving cutting or tying the vas deferens to
traits, three show the first dominant trait and second
prevent sperm release. This minor surgery does not
recessive trait, three the first recessive and second
affect hormone levels or sexual function but blocks
dominant trait, and one shows both recessive traits.
sperm from mixing with semen. Tubal ligation is
its female counterpart, while condoms and pills are 12. Which disorder is characterized by an abnormal
temporary methods. increase in the RBC count, sometimes due to excessive
erythropoietin production?
9. Which of the following is NOT a Sexually Transmitted
(A) Leukemia
Disease (STD)?
(B) Sickle-cell anemia
(A) Chlamydia
(C) Polycythemia
(B) Gonorrhea
(D) Hemophilia
(C) Ringworm
(D) Trichomoniasis

Ans

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 PRACTICE PAPER 02

(C) Polycythemia (D) A protein that degrades DNA

Polycythemia involves an elevated red blood cell (RBC)

Ans
count, thickening blood and potentially raising the risk
of clots. It may result from high altitude adaptation, (A) A non-coding region of DNA that binds RNA
excessive erythropoietin, or a myeloproliferative polymerase
disorder. Leukemia affects white blood cells, sickle-cell A promoter is a regulatory DNA sequence upstream of
anemia distorts RBC shape, and hemophilia impairs a gene where RNA polymerase attaches and initiates
blood clotting factors. transcription. Though non-coding, promoters are
essential for controlling gene expression levels and
13. How does incomplete dominance differ from timing. They contain binding sites for transcription
codominance? factors that modulate the efficiency of RNA polymerase
(A) In incomplete dominance, both alleles are fully binding and transcription initiation.
expressed; in codominance, neither is expressed
16. Which experiment by Alfred Hershey and Martha
(B) In incomplete dominance, alleles blend to produce
an intermediate; in codominance, both alleles Chase confirmed DNA as the genetic material using
appear distinctly bacteriophages?
(C) In codominance, one allele completely masks the (A) Blender experiment
other (B) Meselson–Stahl experiment
(D) They are identical phenomena (C) Griffith’s transformation experiment
(D) Avery–MacLeod–McCarty experiment


Ans


Ans
(B) In incomplete dominance, alleles blend to produce
an intermediate; in codominance, both alleles appear (A) Blender experiment
distinctly Hershey and Chase’s “blender experiment” used
In incomplete dominance, neither allele fully dominates, radioactively labeled bacteriophage T2. Phage DNA
and the phenotype is a blend (e.g., pink flowers from was labeled with 32P, and protein coats were labeled
red and white parents). In codominance, both alleles with 35S. After infection and blending to separate phage
in a heterozygote are expressed independently and coats from bacteria, only 32P entered the bacterial cells,
equally (e.g., AB blood group). Thus, the key difference indicating DNA was the genetic material, not protein.
is blended expression versus parallel expression. 17. Which molecule delivers amino acids to the ribosome
14. Which of the following does NOT follow Mendelian during translation?
inheritance? (A) mRNA
(A) Monohybrid tall/dwarf pea plant cross (B) tRNA
(B) ABO blood group inheritance (C) rRNA
(C) Dihybrid cross of pea color and shape (D) DNA polymerase
(D) Eye color in fruit flies involving a single gene

Ans


Ans (B) tRNA
(B) ABO blood group inheritance Transfer RNA (tRNA) serves as the adaptor molecule
ABO blood groups involve multiple alleles (A, B, and that brings specific amino acids to the ribosome,
O) and codominance for A and B alleles, deviating matching its anticodon to the mRNA codon. Each
from simple Mendelian patterns. In contrast, typical tRNA binds a particular amino acid, ensuring accurate
monohybrid and dihybrid pea crosses adhere to incorporation into the growing polypeptide chain.
Mendelian inheritance, and basic fruit fly eye color (if mRNA provides the coding template, while rRNA forms
controlled by a single gene) follows Mendelian ratios. part of the ribosome’s structural and catalytic core.

18. How does transcription differ between prokaryotes and

15. What is a promoter in the context of gene expression?
(A) A non-coding region of DNA that binds RNA eukaryotes?
polymerase (A) Only eukaryotes need a template strand
(B) A specific tRNA anticodon (B) Prokaryotes have post-transcriptional splicing
(C) An enzyme that synthesizes mRNA (C) Eukaryotes process pre-mRNA by splicing out
introns

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(D) Transcription occurs entirely in the cytoplasm for (D) It cannot replicate in human cells
eukaryotes

Ans


Ans (C) It attacks helper T-lymphocytes
(C) Eukaryotes process pre-mRNA by splicing out HIV targets CD4+ helper T cells, a key component of the
introns adaptive immune response. By progressively destroying
In eukaryotes, the primary RNA transcript (pre-mRNA) these cells, HIV impairs the body’s ability to mount
undergoes splicing to remove introns, plus 5′ capping an effective immune reaction against infections. This
and 3′ polyadenylation before leaving the nucleus. depletion underlies the immunocompromised state
Prokaryotes usually lack introns, so mRNA is typically in AIDS, making patients susceptible to opportunistic
used as synthesized. Both require a template strand, infections and cancers.
but splicing is specific to eukaryotic gene expression
22. Which of the following diseases is NOT transmitted by
processes.
mosquitoes?
19. Which period is known as the “age of reptiles,” (A) Dengue
characterized by dinosaurs? (B) Filaria
(A) Paleozoic era (C) Typhoid
(B) Mesozoic era (D) Malaria
(C) Cenozoic era

Ans
(D) Precambrian era
(C) Typhoid


Ans Typhoid, caused by Salmonella typhi, typically spreads
(B) Mesozoic era through contaminated food or water. Dengue and
The Mesozoic era, spanning roughly 252 to 66 million malaria are transmitted by specific mosquitoes (Aedes
years ago, is often called the “age of reptiles” due to the and Anopheles, respectively), while filariasis (filaria) is
dominance of dinosaurs. It includes the Triassic, Jurassic, also mosquito-borne. Reducing mosquito populations
and Cretaceous periods. The Paleozoic preceded it, the or exposure is crucial for controlling these vector-borne
Cenozoic followed it, and the Precambrian encompasses illnesses, but it is irrelevant to typhoid prevention.
all time before complex life arose.
23. Which condition is characterized by the uncontrolled
20. What is genetic drift? growth of abnormal cells that can invade or spread to
(A) A purposeful selection of advantageous traits other parts of the body?
(B) Random changes in allele frequencies over (A) Arthritis
generations (B) Cancer
(C) The direct transfer of genes by viral infection (C) Influenza
(D) Migration of individuals with new traits (D) Diabetes


Ans

Ans
(B) Random changes in allele frequencies over (B) Cancer
generations Cancer involves aberrant cells undergoing unchecked
Genetic drift is a chance-driven mechanism where allele proliferation and evading normal regulatory
frequencies in a small population fluctuate randomly mechanisms. These malignant cells can metastasize,
from one generation to the next. It is independent of colonizing distant tissues. Genetic and environmental
selective advantage, unlike natural selection. Over time, factors, including carcinogens, lifestyle, and infections,
drift can lead to the fixation or loss of alleles, influencing often contribute to the onset. Early detection and
genetic diversity significantly, especially in isolated treatments like surgery, chemotherapy, and radiation
populations. help manage or eliminate cancerous growths.

21. Why might a pathogen like HIV weaken the immune 24. Which group of microorganisms converts milk to curd
system so severely? by producing lactic acid?
(A) It multiplies inside RBCs (A) Saccharomyces (yeasts)
(B) It exclusively infects bone tissue (B) Lactic acid bacteria
(C) It attacks helper T-lymphocytes (C) Acetobacter (acetic acid bacteria)

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 PRACTICE PAPER 02

(D) Cyanobacteria

Ans

Ans (C) DNA ligase

DNA ligase seals nicks in the sugar-phosphate backbone,
(B) Lactic acid bacteria
joining Okazaki fragments during replication and
Lactic acid bacteria like Lactobacillus species ferment
uniting restriction enzyme-cut DNA fragments with
lactose in milk, producing lactic acid that coagulates
vectors in cloning processes. Helicase unwinds DNA,
milk proteins, forming curd. Yeasts ferment sugars to
RNA polymerase synthesizes RNA, and Taq polymerase
alcohol, acetobacter converts ethanol to acetic acid,
is used in PCR. Ligase’s ability to form phosphodiester
and cyanobacteria are photosynthetic organisms. The
bonds underpins molecular cloning.
specific acidity from lactic acid bacteria gives curd its
tangy taste and texture. 28. Golden Rice is genetically engineered to produce higher
amounts of which nutrient?
25. In sewage treatment, what is the main role of activated
(A) Vitamin A (beta-carotene)
sludge?
(B) Vitamin C
(A) Disinfect water with chlorine
(C) Iron
(B) Oxidize heavy metals
(D) Calcium
(C) Degrade organic matter via microbial activity
(D) Remove large debris mechanically

Ans

Ans (A) Vitamin A (beta-carotene)

Golden Rice is fortified with genes that boost beta-
(C) Degrade organic matter via microbial activity
carotene production in the rice endosperm, addressing
Activated sludge is rich in microorganisms—bacteria
Vitamin A deficiency in regions where rice is a staple.
and protozoa—that metabolize organic waste in
Beta-carotene is converted to Vitamin A in the human
sewage, reducing its biochemical oxygen demand. This
body, helping prevent vision problems and immune
biological process is crucial for secondary treatment,
deficiencies associated with low Vitamin A intake.
ensuring cleaner effluent. Chlorination disinfects, while
mechanical filtration removes large debris. Heavy metal 29. How do genetically modified Bt crops confer resistance
removal typically requires specialized processes beyond to insect pests?
standard biological treatment. (A) They synthesize mammalian hormones
(B) They release a pheromone to repel insects
26. Which microbe is commonly used to produce the
(C) They produce Cry toxins that destroy insect gut
antibiotic penicillin?
cells
(A) Penicillium notatum
(D) They undergo rapid leaf fall when attacked
(B) Escherichia coli
(C) Streptococcus pyogenes

Ans
(D) Clostridium tetani (C) They produce Cry toxins that destroy insect gut cells


Ans Bt crops harbor genes from Bacillus thuringiensis
encoding Cry proteins, which are toxic to certain
(A) Penicillium notatum
insects. When ingested by the pest, these proteins create
Penicillium notatum (and later improved strains like
pores in the insect’s gut lining, leading to paralysis and
Penicillium chrysogenum) produce the antibiotic
death. This mechanism reduces reliance on synthetic
penicillin. This discovery by Alexander Fleming
insecticides and can enhance crop yields.
revolutionized infectious disease treatment by inhibiting
cell wall synthesis in many bacteria. Escherichia coli is 30. Which technique uses restriction fragment length
a gut bacterium, Streptococcus pyogenes causes strep polymorphisms for unique identification in forensic
throat, and Clostridium tetani triggers tetanus. investigations?
(A) ELISA
27. Which enzyme is used to join desired gene fragments
(B) Western blot
with vectors in recombinant DNA technology?
(C) DNA fingerprinting
(A) Helicase
(D) Spectrophotometry
(B) RNA polymerase
(C) DNA ligase

Ans
(D) Taq polymerase

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(C) DNA fingerprinting (D) Habitat fragmentation

DNA fingerprinting (or DNA profiling) examines

Ans
variations in restriction fragment length polymorphisms
(RFLPs) or short tandem repeats (STRs) to produce a (A) Ecological niche
unique genetic pattern. This method is widely employed An ecological niche encompasses the sum of
in forensic science, paternity testing, and population conditions—abiotic and biotic—under which a species
genetics. ELISA and Western blot detect proteins, while can survive, reproduce, and maintain viable populations.
spectrophotometry measures absorbance of light. It includes resource use, habitat preferences, and
interactions. An ecotone is a transition area between
31. Why are buffer zones around protected areas important ecosystems, edge effect concerns boundary habitats, and
for biodiversity conservation? fragmentation is the breaking of continuous habitats.
(A) They permanently exclude all human activities
34. What is carrying capacity?
(B) They create intermediate zones that minimize
habitat disturbance (A) The speed at which a population expands
(C) They are used exclusively for heavy industrial (B) The maximum population size an environment can
manufacturing support
(D) They do not influence core protected habitats (C) The total number of species in a biome
(D) The density of predators in a region


Ans


Ans
(B) They create intermediate zones that minimize
habitat disturbance (B) The maximum population size an environment can
Buffer zones provide a gradual transition between highly support
protected core areas and regions of more intensive Carrying capacity is the largest population of a particular
human activity. By limiting disruptive practices, these species that an environment’s resources can sustain over
zones reduce edge effects and habitat fragmentation, time without significant degradation. It is influenced by
supporting ecological connectivity. They allow limited, resource availability, competition, predation, and other
sustainable use while safeguarding the biodiversity factors. Once reached, population growth stabilizes,
within central conservation zones. transitioning to the stationary phase in a logistic growth
curve.
32. Which of the following is NOT a form of pollution
35. Why is biodiversity conservation crucial for overall
typically addressed when preserving ecosystems?
(A) Air pollution ecosystem stability?
(B) Noise pollution (A) Monocultures are always preferable
(C) Genetic pollution (B) Genetic uniformity eliminates pests
(D) Heat pollution (C) Diverse ecosystems are more resilient to
disturbances


Ans (D) Fewer species minimize competition
(C) Genetic pollution

Ans
While the term “genetic pollution” sometimes refers to
uncontrolled gene flow from GM crops to wild relatives, (C) Diverse ecosystems are more resilient to disturbances
classic environmental preservation efforts usually target Biodiversity enhances an ecosystem’s resilience by
air, water, soil, noise, and thermal pollution. Genetic spreading risk across multiple species and interactions.
contamination can be a concern in specific contexts, When perturbations occur, some species may adapt or
but it is less commonly grouped with standard pollution compensate, helping the system recover. Monocultures
categories. are more vulnerable to diseases or climate fluctuations.
Thus, preserving biodiversity is key to maintaining
33. Which term describes a region where a species is likely long-term ecological stability and productivity.
to survive indefinitely under prevailing environmental
36. Match the following animal diseases with their causal
conditions?
(A) Ecological niche organisms:
(B) Ecotone Column I Column II
(C) Edge effect P. Entamoeba histolytica 1. Malaria

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 PRACTICE PAPER 02

Q. Plasmodium falciparum 2. Amoebiasis (D) A is false, but R is true

R. Wuchereria bancrofti 3. Dengue

Ans
S. Dengue virus 4. Filariasis (C) A is true, but R is false
Options: A high sugar diet is linked to weight gain because sugars
(A) P-2, Q-1, R-4, S-3 are calorie-dense and can be stored as fat if consumed
(B) P-1, Q-2, R-3, S-4 in excess. The reason statement is incorrect: sugar does
(C) P-4, Q-3, R-1, S-2 contain calories. Thus, while the assertion is correct,
(D) P-2, Q-4, R-1, S-3 the accompanying reason is false, invalidating it as an
explanation.


Ans
(A) P-2, Q-1, R-4, S-3 39. Assertion (A) : In most ecosystems, the number of
Malaria is caused by the protozoan Plasmodium primary producers is greater than the number of apex
falciparum (P-2). Amoebiasis is linked to Entamoeba predators.
histolytica (Q-1). Dengue results from infection by the Reason (R) : Energy transfer between trophic levels is
dengue virus (R-4). Filariasis (elephantiasis) is due to the highly efficient, allowing top predators to outnumber
nematode Wuchereria bancrofti (S-3). Each pathogen primary producers.
has distinct transmission and disease manifestations. (A) Both A and R are true, and R is the correct
explanation of A
37. Which combination of statements about energy flow in (B) Both A and R are true, but R is not the correct
an ecosystem is correct? explanation of A
I. Energy flow is unidirectional. (C) A is true, but R is false
II. About 10% of energy is transferred to the next (D) A is false, but R is true
trophic level.

Ans
III. Decomposers fix solar energy directly.
IV. Producers convert light energy into chemical (C) A is true, but R is false
energy. Ecosystems usually have more producers than top-level
V. Primary consumers outnumber producers in total consumers, forming a pyramid of numbers. However,
energy content. energy transfer is not highly efficient—only about 10%
(A) I, II, and IV moves up each level—so apex predators are fewer than
(B) II, III, and V producers. Therefore, the assertion is correct, but the
(C) I, IV, and V reason, stating transfer is “highly efficient,” is false.
(D) I, III, and IV
40. Arrange the following stages of sewage treatment in the


Ans correct sequence:
(A) I, II, and IV 1. Primary sedimentation
Energy flows in one direction (unidirectional), from 2. Chlorination
the sun to producers and then to consumers, with only 3. Grit and debris removal
about 10% passing to each subsequent level. Producers 4. Biological treatment (secondary)
indeed convert light energy into chemical energy via (A) 3 → 1 → 4 → 2
photosynthesis. Decomposers do not fix solar energy (B) 1 → 3 → 2 → 4
directly, and producers generally hold more total energy (C) 3 → 4 → 1 → 2
than primary consumers. (D) 4 → 1 → 3 → 2


Ans
38. Assertion (A) : A high sugar diet can contribute to
obesity. (A) 3 → 1 → 4 → 2
Reason (R) : Sugar contains no calories. Treatment typically begins with grit and debris removal
(A) Both A and R are true, and R is the correct (3), followed by primary sedimentation (1) to settle
explanation of A suspended solids. Next, secondary treatment (4) uses
(B) Both A and R are true, but R is not the correct activated sludge for biological degradation. Finally,
explanation of A chlorination or another disinfection step (2) ensures
(C) A is true, but R is false

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pathogen reduction before discharging treated water (C) By providing nursery grounds for fish and
into the environment. crustaceans
The study emphasizes that mangrove forests serve


Direction :Carefully read the case study provided and then as protective nursery habitats for juvenile fish and
thoroughly answer the subsequent five questions. crustaceans. Their intricate roots offer shelter from
A coastal community relies heavily on mangrove forests for predators and abundant food, boosting survivorship.
fishery resources, storm protection, and local livelihoods. Consequently, local fisheries thrive as adult populations
However, increasing coastal development and pollution grow, supporting subsistence and commercial fishing.
threaten these ecosystems, causing loss of mangrove cover Losing these nurseries decreases marine biodiversity
and reduced nursery habitats for marine organisms. and productivity.
Researchers observe that mangroves protect shorelines
from erosion and provide breeding grounds for various 43. Which human activity mentioned in the passage
fish and crustacean species, supporting subsistence and specifically threatens mangrove health?
commercial fishing activities. Additionally, they sequester (A) Ecotourism
large amounts of carbon, mitigating climate change. (B) Sustainable fishing
Conservation groups advocate planting mangrove (C) Training locals to protect saplings
saplings and regulating industrial discharge to preserve (D) Industrial discharge
water quality. Community engagement programs include

Ans
training locals in sustainable fishing practices and
ecotourism initiatives. The collaborative approach fosters (D) Industrial discharge
environmental awareness, aiming to balance economic The passage states that pollution from industrial sources
needs with mangrove restoration for long-term ecological degrades water quality, harming mangrove roots and
and socioeconomic stability. associated marine life. Toxic effluents can inhibit plant
growth or kill sensitive organisms, undermining the
41. Which key function of mangroves is highlighted in the mangrove ecosystem’s stability. By regulating discharge
case study regarding climate change mitigation? and improving waste treatment, communities can
(A) Producing freshwater springs preserve mangroves’ crucial ecological functions.
(B) Sequestering carbon
44. What dual approach is suggested to ensure long-term
(C) Removing atmospheric nitrogen only
(D) Preventing salt formation ecological and economic benefits?
(A) Total ban on fishing and aquaculture


Ans (B) Introducing invasive species for profit
(B) Sequestering carbon (C) Balancing mangrove restoration with community
According to the study, mangroves store significant livelihood needs
carbon within their biomass and root systems, playing an (D) Relocating all coastal residents inland
essential role in mitigating climate change. Their dense

Ans
root networks trap sediments, reducing carbon release.
By maintaining healthy mangrove forests, coastal (C) Balancing mangrove restoration with community
communities help lower greenhouse gas concentrations livelihood needs
while benefiting from stabilized shorelines and rich The text highlights ecotourism initiatives and
marine habitats. sustainable fishing practices designed to preserve
mangroves while maintaining local income. By engaging
42. How do mangroves benefit local fisheries according to communities in restoration efforts and responsible
the passage? resource management, ecosystems remain healthy, and
(A) By reducing fish reproduction economic opportunities persist. This balanced strategy
(B) By releasing harmful chemicals fosters long-term ecological resilience alongside stable,
(C) By providing nursery grounds for fish and beneficial livelihoods for coastal populations.
crustaceans
45. Why do the researchers advocate planting mangrove
(D) By attracting only large predator species
saplings?


Ans (A) To increase storm surge vulnerability
(B) To eliminate local marine life

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 PRACTICE PAPER 02

(C) To restore degraded mangrove cover 47. Why is incorporating legumes in crop rotation
(D) To reduce carbon uptake beneficial, as per the case study?


Ans (A) Legumes demand heavy pesticide usage
(B) They promote soil acidification
(C) To restore degraded mangrove cover (C) They fix atmospheric nitrogen, enhancing soil
Planting mangrove saplings replenishes damaged fertility
forest areas, reinforcing shoreline protection, carbon (D) They always require industrial fertilizers
sequestration, and nursery habitats. By expanding
mangrove coverage, communities bolster the

Ans
ecosystem’s capacity to support diverse species and (C) They fix atmospheric nitrogen, enhancing soil
safeguard coastal regions against erosion and extreme fertility
weather events. This reforestation effort underpins both Many legumes host nitrogen-fixing bacteria in their
environmental preservation and long-term community root nodules, converting atmospheric nitrogen into
welfare. usable forms for plants. By rotating legumes with other
crops, farmers naturally boost nitrogen levels, reducing


Direction :Carefully read the case study provided and then dependence on synthetic fertilizers. This enriches soil
thoroughly answer the subsequent five questions. quality, maintains long-term fertility, and supports
In a mountainous region, farmers depend on terrace higher yields across successive growing seasons.
agriculture for rice cultivation. Recent studies reveal that
soil erosion and nutrient depletion threaten productivity. 48. How do indigenous earthworm species aid soil health in
Monsoon rains can wash away topsoil on steep slopes, terrace farms?
reducing arable land and crop yields. Agricultural (A) By sealing the soil surface
experts recommend contour bunding, crop rotation with (B) By consuming beneficial microbes
legumes, and organic manure application to replenish soil (C) By aerating soil and decomposing organic matter
fertility. They also stress the role of indigenous earthworm (D) By causing landslides
species in aerating the soil and breaking down organic

Ans
matter. Local communities report improved harvests
after adopting sustainable practices, though the cost of (C) By aerating soil and decomposing organic matter
transitioning remains a challenge. Government agencies Earthworms burrow through soil, improving aeration
launch extension programs, providing seeds, training, and and drainage while also breaking down decaying
micro-loans to facilitate eco-friendly farming. Balanced plant material into simpler compounds. Their castings
land management preserves mountain ecosystems while enrich the soil with nutrients, enhancing fertility. In
ensuring economic viability and food security for these mountainous terrace systems, this biological activity
upland dwellers. helps maintain healthy root environments and
contributes to the sustainable productivity of crops like
46. Which practice mentioned helps reduce soil erosion in rice.
steep terrains?
49. Which major challenge hinders farmers from fully
(A) Discharging industrial pollutants
(B) Contour bunding adopting eco-friendly farming methods?
(C) Monocropping for years (A) Lack of government support
(D) Draining wetlands (B) Permanent ban on all seed varieties
(C) Excessive soil fertility


Ans (D) High transition costs
(B) Contour bunding

Ans
Contour bunding involves constructing embankments
along the land’s contours, slowing water runoff and (D) High transition costs
preventing soil from being washed away. On steep slopes, The passage notes that while sustainable practices
this practice is particularly effective, allowing rainwater improve yields and ecological balance, the initial
to infiltrate rather than erode. By combining contour financial burden can be prohibitive. Investments in
bunding with other sustainable techniques, farmers training, materials, and infrastructure may exceed
protect valuable topsoil and maintain productivity. farmers’ budgets. Micro-loans and government
programs aim to bridge this gap, allowing communities

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to transition gradually to methods that preserve soil and

livelihoods.

50. Why do government agencies provide seeds, training,

and loans to upland farmers?
(A) To force monoculture of cash crops
(B) To promote purely ornamental gardens
(C) To facilitate eco-friendly and sustainable agriculture
(D) To prohibit all crop diversification


Ans
(C) To facilitate eco-friendly and sustainable agriculture
The case study highlights that government agencies
support farmers through extension programs offering
resources and knowledge. By supplying improved
seed varieties, technical training, and financial aid,
officials encourage sustainable practices. This approach
bolsters soil conservation, maintains productivity,
and safeguards mountain ecosystems, ensuring both
environmental and economic resilience for upland
communities.

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 PRACTICE PAPER 03

PRACTICE PAPER 03

1. Which term describes the development of seeds without Hence, it is not classified as a post-fertilization process
fertilization in certain flowering plants? in flowering plants.
(A) Parthenogenesis
4. Which process in human spermatogenesis directly
(B) Apomixis
(C) Polyembryony results in the transformation of spermatids into
(D) Parthenocarpy functional spermatozoa?
(A) Meiosis I


Ans (B) Meiosis II
(B) Apomixis (C) Spermiogenesis
Apomixis is a mode of asexual reproduction allowing (D) Capacitation
seed formation without fusion of gametes. This bypasses

Ans
the typical fertilization process, yet still yields viable
seeds. It maintains maternal genetic traits without (C) Spermiogenesis
introducing variation, which can be beneficial for Spermiogenesis is the final phase of spermatogenesis,
preserving desirable features in certain plant cultivars. during which round spermatids differentiate into
mature spermatozoa. This involves the formation of a
2. Which floral structure produces the male gametophyte tail for motility and condensation of nuclear material,
in angiosperms? enabling functional male gametes capable of fertilizing
(A) Anther the ovum.
(B) Stigma
5. Which hormone primarily triggers ovulation in the
(C) Style
(D) Ovary menstrual cycle?
(A) Follicle Stimulating Hormone (FSH)


Ans (B) Luteinizing Hormone (LH)
(A) Anther (C) Estrogen
In flowering plants, the anther contains microsporangia (D) Progesterone
where microsporocytes undergo meiosis to form

Ans
microspores, which develop into male gametophytes
or pollen grains. This process ensures the production of (B) Luteinizing Hormone (LH)
male gametes essential for pollination and fertilization, The surge in luteinizing hormone around the midpoint
thereby enabling sexual reproduction in angiosperms. of the menstrual cycle is the critical factor that induces
ovulation, causing the mature ovarian follicle to rupture
3. Which of the following is NOT a post-fertilization event and release the secondary oocyte. This hormonal
in flowering plants? mechanism is pivotal in female reproductive physiology.
(A) Endosperm development
6. Which part of the female reproductive system is
(B) Embryo formation
(C) Seed maturation primarily the site of fertilisation?
(D) Pollen tube growth (A) Uterus
(B) Fallopian tube


Ans (C) Cervix
(D) Pollen tube growth (D) Vagina
Post-fertilization events include endosperm

Ans
development, embryo formation, and eventual
seed maturation. Pollen tube growth occurs before (B) Fallopian tube
fertilization to deliver male gametes to the embryo sac.

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Fertilization typically takes place in the ampullary region 10. Which comparison correctly differentiates incomplete
of the Fallopian tube, where the ovum and spermatozoa dominance from co-dominance?
meet. Conditions in this region are optimal for gamete (A) Both alleles fully expressed in incomplete
fusion and subsequent zygote formation, marking the dominance, partially in co-dominance
earliest stage of pregnancy. (B) Phenotype is intermediate in incomplete
dominance, both alleles visible in co-dominance
7. Which term describes the prevention of implantation or (C) Both alleles are masked in incomplete dominance,
fertilization to control birth? both are silent in co-dominance
(A) Contraception (D) One allele is lethal in incomplete dominance, none
(B) Lactation is lethal in co-dominance
(C) Amniocentesis
(D) Parturition

Ans

Ans (B) Phenotype is intermediate in incomplete dominance,

both alleles visible in co-dominance
(A) Contraception In incomplete dominance, a blending of parental traits
Contraception refers to methods employed to prevent produces an intermediate phenotype. In co-dominance,
fertilization or implantation of an embryo. It spans both alleles manifest distinctly. A classic example
barrier devices, intrauterine devices, hormonal pills, includes human ABO blood groups (co-dominance)
and other strategies. These measures help regulate versus snapdragon flower color (incomplete
population growth and support reproductive health by dominance).
allowing couples to choose if and when to conceive.
11. Which blood group represents the universal recipient in
8. Which of the following is NOT an assisted reproductive the ABO system?
technology (ART)? (A) A
(A) In Vitro Fertilization (IVF) (B) B
(B) Zygote Intra-Fallopian Transfer (ZIFT) (C) AB
(C) Gamete Intra-Fallopian Transfer (GIFT) (D) O
(D) Tubectomy


Ans


Ans
(C) AB
(D) Tubectomy Individuals with AB blood type can receive blood from
Tubectomy is a surgical sterilization procedure all ABO groups because they possess both A and B
preventing the egg and sperm from meeting by blocking antigens on their red blood cells, and neither anti-A nor
or cutting the fallopian tubes. It is not classified as an anti-B antibodies in plasma. This property makes them
assisted reproductive technology, which involves aiding universal recipients.
or enhancing fertility to achieve pregnancy.
12. Identify the statements that correctly describe sex-
9. Amniocentesis is primarily conducted to: linked inheritance:
(A) Determine fetal lung maturity I. Hemophilia is an X-linked recessive disorder
(B) Identify fetal sex and genetic disorders II. Color blindness is Y-linked
(C) Increase chances of pregnancy III. Males have a higher chance of expressing X-linked
(D) Lower mother’s blood pressure recessive traits


Ans IV. Fathers pass X-linked genes to all daughters
(B) Identify fetal sex and genetic disorders (A) I and III
Amniocentesis involves sampling amniotic fluid to (B) II and III
detect chromosomal abnormalities, genetic disorders, (C) I, III, and IV
and fetal sex. It helps parents and healthcare providers (D) I, II, and IV
prepare or make informed decisions about the

Ans
pregnancy. However, misuse for sex determination is (C) I, III, and IV
illegal in many jurisdictions. Hemophilia is an X-linked recessive disorder, and
males are more prone to expressing X-linked recessive

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 PRACTICE PAPER 03

traits. Fathers indeed pass their X-linked genes to all (C) Similar molecular structures across species
daughters. Color blindness is typically X-linked, not (D) Independent origins with no similarities
Y-linked, making statement II incorrect.

Ans
13. What is the central dogma of molecular biology? (D) Independent origins with no similarities
(A) DNA → RNA → Protein Biological evolution is supported by fossil records,
(B) RNA → DNA → Protein embryological parallels, and molecular similarities
(C) Protein → RNA → DNA (DNA or protein homologies) across species. These
(D) RNA → Protein → DNA reflect common ancestry. The concept of completely


Ans independent origins with no shared features does not
align with evolutionary theory.
(A) DNA → RNA → Protein
The central dogma states that genetic information 17. Arrange the following human evolution stages in correct
flows from DNA to mRNA through transcription and chronological sequence:
subsequently from mRNA to protein via translation. It A. Homo habilis
underlies how genetic instructions are expressed within B. Homo sapiens
cells, shaping all biological processes. C. Homo erectus
D. Australopithecus
14. Which enzyme unwinds the DNA helix during (A) D → A → C → B
replication? (B) D → C → A → B
(A) DNA gyrase (C) A → D → B → C
(B) DNA helicase (D) C → D → A → B
(C) DNA polymerase III
(D) Ligase

Ans

Ans (A) D → A → C → B
Australopithecus preceded Homo habilis, which was
(B) DNA helicase followed by Homo erectus, culminating in Homo
DNA helicase unzips the double-stranded DNA by sapiens. This sequence outlines pivotal milestones in
breaking hydrogen bonds between complementary hominin evolution, showcasing an increase in cranial
strands, forming a replication fork. This unwinding capacity and refined tool usage.
is essential to expose the template strands so that
DNA polymerases can replicate the genetic material 18. Which mechanism best explains why certain traits
accurately. increase in frequency due to advantageous adaptations
in a population?
15. Which regulatory gene system exemplifies an inducible (A) Genetic drift
operon in prokaryotes? (B) Gene flow
(A) Lac operon (C) Natural selection
(B) Trp operon (D) Mutation
(C) Ara operon
(D) His operon

Ans

Ans (C) Natural selection

Natural selection is the process where individuals
(A) Lac operon with beneficial heritable traits outcompete others
The lac operon is an inducible system where lactose acts and reproduce more successfully. Over successive
as an inducer, inactivating the repressor and enabling generations, these advantageous traits become more
gene transcription. This allows E. coli to metabolize common, driving evolutionary change. This mechanism
lactose only when it is available, conserving cellular is central to Darwinian theory and explains the adaptive
energy. fit of organisms to their environment.
16. Which of the following is NOT considered an evidence 19. Which pathogen causes malaria in humans?
for biological evolution? (A) Plasmodium species
(A) Fossil records (B) Leishmania donovani
(B) Comparative embryology (C) Entamoeba histolytica

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(D) Trypanosoma gambiense (B) Lactobacillus bulgaricus

Ans Lactobacillus bulgaricus helps ferment lactose in milk,
producing lactic acid. This lowers pH, causing milk
(A) Plasmodium species proteins to coagulate into curd. This bacterium, often
Malaria in humans is caused by different species of used alongside Streptococcus thermophilus, gives curd
Plasmodium (e.g., P. vivax, P. falciparum). The parasite its distinctive taste and texture.
is transmitted via female Anopheles mosquitoes, leading
to periodic fevers, chills, and potential complications 23. Which enzyme is primarily used to cut DNA at specific
such as severe anemia or organ failure if untreated. recognition sites in genetic engineering?
(A) DNA ligase
20. How do vaccines differ from antibiotics in controlling (B) DNA polymerase
infectious diseases? (C) Restriction endonuclease
(A) Vaccines treat ongoing infections; antibiotics (D) Reverse transcriptase
prevent future infections
(B) Vaccines stimulate immune memory; antibiotics

Ans
directly kill microbes (C) Restriction endonuclease
(C) Both are used only in viral infections Restriction endonucleases recognize specific DNA
(D) Both are equally effective against all pathogens sequences (often palindromic) and cleave both


Ans strands, generating fragments for cloning. They are
essential for recombinant DNA technology, enabling
(B) Vaccines stimulate immune memory; antibiotics precise manipulation of genetic material in various
directly kill microbes biotechnological applications.
Vaccines expose the immune system to antigens,
prompting memory cell formation for long-term 24. Assertion (A) : Plasmids are used as vectors in genetic
protection. Antibiotics combat bacterial infections by engineering.
directly inhibiting or killing microbes. Hence, they Reason (R) : Plasmids replicate independently and can
differ fundamentally in mechanism and preventative carry foreign DNA.
versus curative roles. (A) Both (A) and (R) are true, and (R) is the correct
explanation of (A)
21. Which process involves using living organisms to (B) Both (A) and (R) are true, but (R) is not the correct
control pests and diseases? explanation of (A)
(A) Biofertilization (C) (A) is true, (R) is false
(B) Bioaugmentation (D) (A) is false, (R) is true
(C) Biocontrol
(D) Bioremediation

Ans

Ans (A) Both (A) and (R) are true, and (R) is the correct
explanation of (A)
(C) Biocontrol Plasmids serve as commonly used cloning vectors
Biocontrol employs natural predators, parasites, or because they can replicate independently within
pathogens to suppress pest populations, reducing bacterial cells and accommodate foreign DNA inserts.
reliance on chemical pesticides. It aligns with ecological Their autonomous replication and ease of manipulation
principles by using naturally occurring relationships to make them ideal tools in recombinant DNA experiments.
manage agricultural or environmental pests sustainably,
minimizing harmful environmental impacts. 25. Which crop is commonly associated with the Bt gene,
providing resistance against certain insects?
22. Which microbe is crucial in curd formation by (A) Bt Rice
producing lactic acid? (B) Bt Tomato
(A) Saccharomyces cerevisiae (C) Bt Brinjal
(B) Lactobacillus bulgaricus (D) Bt Cotton
(C) Rhizobium leguminosarum
(D) Penicillium notatum

Ans

Ans (D) Bt Cotton

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 PRACTICE PAPER 03

Bt cotton is genetically modified to express Cry proteins (C) A → B → C → D

from Bacillus thuringiensis, which target specific insect (D) C → A → B → D
pests, especially bollworms. This reduces pesticide usage

Ans
and enhances yield. Similar strategies are used in other
genetically modified crops. (A) C → B → A → D
In population growth, organisms initially experience
26. Which of the following is NOT an application of a lag phase (minimal growth), then an acceleration
biotechnology in agriculture? phase (rapid growth), followed by a deceleration phase
(A) Transgenic plants for insect resistance (growth rate slows), and finally a stationary phase
(B) Micropropagation of healthy plant stock (maximum carrying capacity).
(C) Synthetic fertilizers for faster crop growth
29. Which statement best describes energy flow in an
(D) Enhancing plant nutritional content through
genetic engineering ecosystem?
(A) Unidirectional from autotrophs to heterotrophs


Ans (B) Cyclic between producers, consumers, and
(C) Synthetic fertilizers for faster crop growth decomposers
Synthetic fertilizers are chemical compounds that (C) Stored permanently in each trophic level
add nutrients to soil without employing direct (D) Infinite and renewable within the ecosystem
biotechnological methods. The other listed approaches

Ans
involve genetic manipulation or advanced tissue culture,
both integral to biotechnology-driven strategies for (A) Unidirectional from autotrophs to heterotrophs
improving crop traits or propagation methods. Hence, Energy captured by producers through photosynthesis
synthetic fertilizers do not qualify as biotechnology moves unidirectionally through trophic levels and is
applications. eventually lost as heat. Unlike nutrients, which are
recycled, energy flow is not cyclic. This one-way transfer
27. How does mutualism differ from parasitism? underlies the structure of food chains and energy
(A) Both partners benefit in parasitism, only one pyramids in ecosystems.
benefits in mutualism
30. Which factor primarily regulates primary productivity
(B) One partner benefits and the other is harmed in
mutualism, opposite in parasitism in a terrestrial ecosystem?
(C) Both partners benefit in mutualism, only one (A) Light intensity
benefits while the other is harmed in parasitism (B) Temperature
(D) Both partners are harmed in parasitism, none (C) Soil nutrient availability
benefits (D) All of the above equally

Ans

Ans

(C) Both partners benefit in mutualism, only one (D) All of the above equally
benefits while the other is harmed in parasitism Primary productivity is influenced by multiple factors
In mutualism, both partners gain benefits like nutrients including sunlight, temperature, and soil nutrients.
or protection. By contrast, parasitism favors the These elements jointly determine photosynthetic
parasite at the expense of the host, which suffers. Such efficiency, plant growth, and overall energy capture,
interactions can significantly affect population dynamics reflecting the complex interplay that sustains ecosystem
and ecological balance across diverse habitats. functioning.

31. Which term refers to the variety of different species

28. Arrange the following population growth phases in the
correct order: within a region?
A. Deceleration phase (A) Genetic diversity
B. Acceleration phase (B) Species diversity
C. Lag phase (C) Ecological diversity
D. Stationary phase (D) Ecosystem diversity
(A) C → B → A → D

Ans
(B) B → C → A → D (B) Species diversity

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Species diversity assesses how many distinct species 3. Klinefelter’s C. X-linked recessive
are present (richness) and their relative proportions syndrome clotting defect
in a region. It is a key component of biodiversity,
4. Colour blindness D. X-linked recessive
reflecting ecological complexity and resilience. Higher
vision impairment
species diversity helps maintain ecosystem stability and
adaptability, making its preservation essential. Options:
(A) 1-C, 2-A, 3-B, 4-D
32. Assertion (A) : Sacred groves preserve rare plant species. (B) 1-D, 2-B, 3-A, 4-C
Reason (R) : These forests are maintained for strict (C) 1-C, 2-B, 3-A, 4-D
religious or cultural reasons. (D) 1-D, 2-A, 3-C, 4-B
(A) Both (A) and (R) are true, and (R) is the correct


Ans
explanation of (A)
(B) Both (A) and (R) are true, but (R) is not the correct (A) 1-C, 2-A, 3-B, 4-D
explanation of (A) Hemophilia involves defective blood clotting and is
(C) (A) is true, (R) is false X-linked recessive. Down’s syndrome results from an
(D) (A) is false, (R) is true extra copy of chromosome 21. Klinefelter’s syndrome
involves an XXY karyotype in males. Color blindness is


Ans
typically an X-linked recessive vision impairment.
(A) Both (A) and (R) are true, and (R) is the correct
explanation of (A) 35. Match the industrial products (Column I) with the
Sacred groves are patches of forest traditionally corresponding microbes (Column II):
protected on religious or cultural grounds. Because they Column I Column II
are left relatively undisturbed, many rare and endemic
1. Acetic acid A. Aspergillus niger
species survive there, demonstrating the role of cultural
practices in biodiversity conservation. 2. Citric acid B. Acetobacter aceti
3. Bread C. Monascus purpureus
33. Select the correct statements regarding biodiversity 4. Statins D. Saccharomyces cerevisiae
hotspots:
Options
I. They host exceptionally high diversity
(A) 1-B, 2-A, 3-D, 4-C
II. They have low endemism
(B) 1-D, 2-B, 3-C, 4-A
III. They face significant habitat loss
(C) 1-B, 2-C, 3-A, 4-D
IV. They must contain many threatened species
(D) 1-A, 2-D, 3-B, 4-C
(A) I and III
(B) II and III

Ans
(C) I, II, and IV (A) 1-B, 2-A, 3-D, 4-C
(D) I, III, and IV Acetic acid is produced by Acetobacter aceti. Citric acid


Ans is manufactured using Aspergillus niger in large-scale
fermenters. Bread production relies on Saccharomyces
(D) I, III, and IV
cerevisiae for dough fermentation. Statins, cholesterol-
Biodiversity hotspots feature extraordinary species
lowering compounds, originate from Monascus
diversity, high endemism, and face critical habitat loss.
purpureus. Each microbe is chosen for its specific
They also contain numerous threatened species due
metabolic capabilities.
to extensive anthropogenic pressures. Statement II is
incorrect because hotspots usually have substantial 36. Match the following reproductive terms (Column I)
endemism. with their descriptions (Column II):
34. Match the genetic disorders (Column I) with their Column I Column II
characteristics (Column II): 1. Spermatogenesis A. Onset of menstruation
Column I Column II 2. Menarche B. Gamete transfer into
1. Hemophilia A. Extra chromosome 21 fallopian tube
2. Down’s syndrome B. XXY condition

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 PRACTICE PAPER 03

3. Lactation C. Production of sperm in 1. Ex situ A. On-site protection

testes conservation of species in natural
4. GIFT D. Milk secretion post habitat
childbirth 2. In situ B. Off-site conservation of
Options: conservation species
(A) 1-C, 2-A, 3-D, 4-B 3. Biosphere reserve C. Large area protecting
(B) 1-A, 2-C, 3-B, 4-D multiple ecosystems
(C) 1-D, 2-B, 3-A, 4-C 4. Zoo D. Facility where animals
(D) 1-C, 2-D, 3-A, 4-B are kept under human


Ans care

(A) 1-C, 2-A, 3-D, 4-B Options:

Spermatogenesis is the process of sperm formation (A) 1-A, 2-C, 3-B, 4-D
within the seminiferous tubules. Menarche denotes the (B) 1-D, 2-B, 3-C, 4-A
onset of menstruation, marking reproductive maturity (C) 1-B, 2-A, 3-C, 4-D
in females. Lactation is the secretion of milk from (D) 1-C, 2-D, 3-A, 4-B
mammary glands post-partum. GIFT involves placing

Ans
male and female gametes into the fallopian tube for in (C) 1-B, 2-A, 3-C, 4-D
vivo fertilization. Ex situ conservation preserves species outside their
37. Match the following enzymes (Column I) with their natural habitat, such as seed banks or captive breeding.
function in biotechnology (Column II): In situ conservation protects organisms within their
native environment. Biosphere reserves cover broad
Column I Column II habitats for conservation. Zoos house animals under
1. Ligase A. Synthesizes DNA from managed care.
RNA template
39. Which statements about pollination are correct?
2. Reverse B. Amplifies DNA at high
I. Self-pollination decreases genetic variation
Transcriptase temperature
II. Cross-pollination often requires pollinators
3. Taq DNA C. Joins DNA fragments III. Cleistogamy promotes cross-pollination
Polymerase IV. Wind pollination depends on brightly colored
4. Restriction D. Cuts DNA at specific sites flowers
Endonuclease (A) I and II
Options: (B) I, II, and III
(A) 1-D, 2-B, 3-A, 4-C (C) II and IV
(B) 1-C, 2-A, 3-B, 4-D (D) I and III
(C) 1-C, 2-D, 3-B, 4-A

Ans
(D) 1-A, 2-C, 3-D, 4-B
(A) I and II


Ans Self-pollination tends to reduce genetic diversity because
(B) 1-C, 2-A, 3-B, 4-D gametes from the same plant fuse. Cross-pollination
Ligase seals nicks and joins DNA fragments. Reverse usually relies on external agents like insects or wind.
Transcriptase synthesizes complementary DNA from Cleistogamy encourages self-pollination, and wind-
RNA templates. Taq DNA polymerase is heat-stable pollinated flowers are typically not brightly colored.
and is essential in PCR for amplifying DNA at elevated
40. Identify the correct statements regarding immunity:
temperatures. Restriction endonucleases specifically cut
I. Active immunity involves antibody transfer from
DNA at their respective recognition sites.
another source
38. Match the conservation strategies (Column I) with their II. Passive immunity is immediate but short-lived
features (Column II): III. Vaccination induces active immunity
IV. Colostrum provides passive immunity to newborns
Column I Column II
(A) I, III, and IV

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(B) II and III (B) Toxic effect against target insects

(C) II, III, and IV (C) Faster fiber production
(D) I and II (D) Higher nutrient content in seeds


Ans

Ans
(C) II, III, and IV (B) Toxic effect against target insects
Passive immunity is rapid because readymade antibodies Bt cotton produces Cry proteins lethal to certain insect
confer immediate protection but do not last long. pests like bollworms, sparing beneficial organisms and
Vaccination stimulates an individual’s own immune posing no significant risk to humans. This targeted
system, providing active immunity. Colostrum transfers biological defense lessens pest populations effectively,
maternal antibodies, granting passive immunity to contributing to higher yield and reduced pesticide use,
newborns. making agricultural practices more sustainable.

Direction :Carefully read the case study provided and then 43. Which additional measure was implemented to
thoroughly answer the subsequent five questions. maintain sustainability?
“In a rural community near a vast agricultural field, (A) Exclusive pesticide spraying
farmers noticed a drastic reduction in crop yields over (B) Extensive monocropping
several seasons. Investigations revealed that while they (C) Integrated pest management with reduced
had shifted to a single high-yield variety of cotton, the chemicals
incidence of bollworm infestation had risen steadily. The (D) Direct sale to international markets
bollworms appeared resistant to traditional pesticides,

Ans
leading to heavier losses. Scientists recommended
adopting genetically modified Bt cotton seeds that produce (C) Integrated pest management with reduced chemicals
Cry proteins toxic to bollworms but safe for humans. To Alongside Bt cotton adoption, farmers used integrated
ensure sustainable practices, they also advised integrated pest management, including crop rotation and
pest management, including crop rotation and reduced minimized chemical usage. This holistic approach
chemical use. Within two years, the community reported preserves ecological balance by decreasing excessive
higher yields and decreased chemical residue in the soil, pesticide input, thereby fostering healthier soil,
reflecting an improved agricultural ecosystem. Local beneficial organisms, and improved yields.
authorities monitored pest populations and collaborated 44. How did the community benefit ecologically within two
with researchers to train farmers in proper Bt cotton years?
cultivation methods. This approach balanced productivity (A) Rapid depletion of soil microorganisms
with environmental responsibility.” (B) Excess fertilizer usage
41. Which primary reason prompted the shift to Bt cotton (C) Decreased chemical residue in soil
in this farming community? (D) Decline in pollinator numbers
(A) Desire for new pesticide brands

Ans
(B) Lack of fertilizers (C) Decreased chemical residue in soil
(C) Resistance of bollworms to conventional pesticides The case highlights improved soil conditions, evidenced
(D) Favorable market prices for transgenic seeds by lower chemical residues due to fewer pesticide


Ans applications and well-managed integrated pest practices.
(C) Resistance of bollworms to conventional pesticides This outcome supports soil health, beneficial organisms,
The case specifies that bollworms developed resistance and sustainable agricultural productivity over time.
to traditional pesticides, causing serious yield declines. 45. Why did local authorities collaborate with researchers?
Consequently, researchers recommended Bt cotton to (A) To increase pesticide sales
combat pest infestation through Cry proteins, providing (B) To regulate seed patent laws
sustainable pest control while reducing chemical (C) To import foreign cotton varieties
reliance. (D) To train farmers in Bt cotton practices
42. What advantage do Cry proteins provide in Bt cotton?

Ans
(A) Enhanced drought tolerance (D) To train farmers in Bt cotton practices

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 PRACTICE PAPER 03

Authorities, partnering with researchers, guided

Ans

farmers in appropriate Bt cotton cultivation techniques, (C) Confidential counseling and testing
ensuring that Cry protein technology was employed The clinic’s discreet environment encouraged
effectively. This cooperative effort balanced productivity adolescents to seek timely diagnosis and receive
with environmental stewardship, demonstrating the accurate guidance. This open, trust-based approach to
practical value of scientific advisory in agriculture. education and testing lowered stigma, enabling earlier
intervention for STIs, thereby reducing transmission


Direction :Carefully read the case study provided and then
rates among the youth population.
thoroughly answer the subsequent five questions.
“In a suburban healthcare center, officials noticed a rise in 48. Why did the center collaborate with local schools?
sexually transmitted infections (STIs) among adolescents (A) To conduct medical research
and young adults. The center established a youth- (B) To introduce unrelated sports programs
friendly clinic offering confidential counseling, diagnostic (C) To expand farmland
tests, and educational programs on safe sex practices. (D) To organize awareness campaigns and address
Medical staff emphasized early detection and treatment, stigma
highlighting the potential dangers of untreated STIs such


Ans
as HIV/AIDS. Interactive workshops covered condom use,
responsible decision-making, and respectful relationships. (D) To organize awareness campaigns and address
In collaboration with local schools, healthcare workers stigma
organized awareness campaigns to dispel myths and The case details collaborations with schools to hold
stigmas. Over time, reported infections diminished, educational sessions debunking myths and stigmas
indicating improved knowledge and proactive health around sexual health. This partnership broadened
behavior. To ensure sustainability, the clinic continuously reach, informed adolescents about safe practices, and
trained peer educators who connected directly with their improved societal acceptance of open discussions on
age group, creating an open, supportive environment STIs.
for discussing sexual health without judgment. Regular
49. What is the role of peer educators in this initiative?
feedback from participants helped refine services, ensuring
(A) Selling medical insurance
the clinic remained a trusted resource for adolescence-
(B) Conducting major surgeries
related concerns.”
(C) Connecting with their peer group to offer guidance
46. What was the primary concern that prompted the (D) Developing new vaccines
creation of a youth-friendly clinic?

Ans
(A) Excessive maternal deaths
(C) Connecting with their peer group to offer guidance
(B) Rise in sexually transmitted infections among
Peer educators are trained to communicate sexual
adolescents
health information effectively, fostering open dialogue
(C) Scarcity of contraceptives
among their contemporaries. Because they share similar
(D) Increase in infant mortality rates
experiences and ages, they can address questions,


Ans reduce hesitancy, and encourage responsible behaviors.
(B) Rise in sexually transmitted infections among This peer-led approach amplifies outreach and trust
adolescents among adolescents.
The case explicitly states an increase in STIs among
50. Which factor helped maintain the clinic’s long-term
adolescents as the driving factor. This situation spurred
effectiveness?
the healthcare center to provide specialized services,
(A) One-time campaign without follow-up
emphasizing prevention, counseling, and prompt
(B) Infrequent training sessions
treatment of sexually transmitted diseases.
(C) Regular feedback from participants and service
47. Which measure contributed most to reducing STI cases? refinement
(A) Strict legal penalties (D) Elimination of all social media platforms
(B) Abstaining from all social interactions

Ans
(C) Confidential counseling and testing
(D) Mandatory vaccination against influenza

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(C) Regular feedback from participants and service

refinement
The continuous feedback loop allowed the clinic to
adapt its programs based on actual needs and concerns.
By updating strategies, staff maximized the clinic’s
relevance, ensuring it remained a credible, supportive
resource for youth over time.

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 PRACTICE PAPER 04

PRACTICE PAPER 04

1. What does parthenocarpy refer to in flowering plants? (A) Uterus

(A) Seed formation without fertilization (B) Ovary
(B) Fruit formation without seeds (C) Vaginal canal
(C) Development of embryos from nucellus (D) Ampullary region of Fallopian tube
(D) Use of pollinators for cross-fertilization

Ans


Ans (D) Ampullary region of Fallopian tube
(B) Fruit formation without seeds The ampullary region of the Fallopian tube is the usual
Parthenocarpy is the phenomenon where fruits develop site of fertilization, where the ovum meets sperm. This
without seed formation, often induced hormonally or location provides optimal conditions for gamete fusion
genetically. This can yield seedless varieties of fruits and zygote formation before implantation in the uterus.
like bananas, enhancing consumer preference while
5. How does spermatogenesis differ from oogenesis?
bypassing the normal fertilization requirement.
(A) Spermatogenesis produces a single gamete per
2. In double fertilization, one male gamete fuses with the meiotic event; oogenesis yields four functional ova
egg cell, forming the zygote. The other male gamete: (B) Oogenesis continues throughout life;
(A) Degenerates spermatogenesis stops after puberty
(B) Fuses with antipodal cells (C) Spermatogenesis results in four functional sperm;
(C) Fuses with the central cell, forming endosperm oogenesis produces one functional ovum
(D) Fuses with synergids, forming polar nuclei (D) Both processes yield four functional gametes each


Ans

Ans
(C) Fuses with the central cell, forming endosperm (C) Spermatogenesis results in four functional sperm;
In angiosperms, one male gamete fertilizes the egg, oogenesis produces one functional ovum
producing a diploid zygote. The second male gamete During spermatogenesis, meiosis in males generates
fuses with the diploid central cell, forming triploid four viable sperm. In females, oogenesis yields a
endosperm tissue that nourishes the developing embryo. single functional ovum plus three non-functional
polar bodies. This asymmetrical division ensures
3. Which adaptation is frequently observed in wind- maximum cytoplasmic reserves for the ovum, reflecting
pollinated flowers? a fundamental difference between male and female
(A) Bright, fragrant petals gametogenesis.
(B) Sticky pollen grains
(C) Large, feathery stigmas 6. Which of the following is NOT a function of the
(D) Nectar production placenta?


Ans (A) Facilitating nutrient exchange
(B) Secreting essential hormones
(C) Large, feathery stigmas (C) Removing fetal wastes
Wind-pollinated flowers typically have inconspicuous (D) Producing antibodies that attack maternal tissues
petals, produce lightweight pollen, and possess large,
feathery stigmas to trap airborne pollen. Fragrances and

Ans
nectar are not usually necessary because pollinators like (D) Producing antibodies that attack maternal tissues
insects or birds are not involved. The placenta mediates nutrient and gas exchange
between fetus and mother, removes fetal wastes, and
4. Where does fertilization typically occur in the female secretes hormones like hCG. It does not produce
reproductive tract?

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antibodies harmful to maternal tissues, helping maintain dominance

a healthy pregnancy.

Ans
7. Which term describes the intentional termination of (B) One gene affects multiple phenotypic traits
pregnancy before fetal viability for medical or personal Pleiotropy occurs when a single gene influences
reasons? multiple distinct characteristics. For instance, in
(A) Sterilization phenylketonuria, a single defective gene leads to
(B) Implantation intellectual disability, altered pigmentation, and other
(C) Medical Termination of Pregnancy (MTP) metabolic problems. This illustrates how one gene can
(D) Tubal ligation generate diverse effects in an organism.


Ans 11. Identify the correct statements regarding Mendelian
(C) Medical Termination of Pregnancy (MTP) inheritance:
MTP refers to the deliberate end of a pregnancy using I. Traits segregate during gamete formation
medical or surgical procedures, typically performed II. Parental traits blend completely in offspring
when continuation poses health risks or under lawful III. Genes for different traits may assort independently
personal choice. It is regulated to ensure safety and IV. Dominant alleles always prevent recessive
informed consent. expression
(A) I and III
8. Which reproductive technology involves transferring (B) II, III, and IV
an early embryo into the fallopian tube? (C) I, II, and III
(A) ICSI (D) I, III, and IV
(B) ZIFT
(C) IUI

Ans
(D) IVF-ET (A) I and III


Ans Mendel’s laws state that alleles segregate independently
(Law of Segregation) and different gene pairs can assort
(B) ZIFT independently (Law of Independent Assortment).
In Zygote Intra-Fallopian Transfer, a zygote or early Complete blending is not typical in Mendelian genetics,
embryo (up to 8 blastomeres) is placed directly into and recessive alleles can be expressed in homozygous
the fallopian tube. This differs from IVF-ET, where the recessive conditions.
embryo is typically transferred into the uterus.
12. Haemophilia is transmitted:
9. Which of the following is NOT a sexually transmitted (A) Autosomally and dominantly
infection? (B) X-linked and recessive
(A) Syphilis (C) Y-linked and dominant
(B) Gonorrhea (D) Autosomally and recessive
(C) Chikungunya
(D) Genital herpes

Ans

Ans (B) X-linked and recessive

Haemophilia often arises from an X-linked recessive
(C) Chikungunya allele. Males with this faulty allele express the disorder,
Syphilis, gonorrhea, and genital herpes are classical while females typically need two defective alleles
STIs, typically transmitted through sexual contact. to manifest the condition. Carriers can pass it to
Chikungunya, however, is transmitted by mosquitoes subsequent generations.
(Aedes species) and does not spread primarily through
sexual routes, making it an exception in this list. 13. What is a codon?
(A) A basic structural unit of proteins
10. Which statement accurately describes pleiotropy? (B) The site of ribosome synthesis
(A) Multiple genes control a single trait (C) A three-nucleotide sequence on mRNA specifying
(B) One gene affects multiple phenotypic traits an amino acid
(C) Traits that skip generations (D) An enzyme involved in transcription
(D) Non-Mendelian inheritance involving incomplete

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 PRACTICE PAPER 04

Ans (B) Involves the exchange of alleles between populations

(C) A three-nucleotide sequence on mRNA specifying (C) Occurs only in plants
an amino acid (D) Has no effect on allele frequencies
A codon is a triplet of nucleotides on mRNA that

Ans
corresponds to a specific amino acid or signals start/
(B) Involves the exchange of alleles between populations
stop of translation. This genetic code governs how
Gene flow is the transfer of alleles among populations
proteins are synthesized in living organisms.
through migration or gamete dispersal, altering genetic
14. Which process does NOT directly involve RNA? structure. It can enhance genetic diversity within a
(A) Transcription population while reducing genetic differences between
(B) RNA processing groups, influencing evolutionary dynamics across
(C) Translation habitats.
(D) DNA replication
18. Arrange the following theories of evolution


Ans chronologically:
(D) DNA replication A. Darwin’s theory of natural selection
Transcription synthesizes RNA from DNA, RNA B. Lamarck’s theory of inheritance of acquired traits
processing modifies RNA transcripts, and translation C. Modern synthetic theory
decodes mRNA into proteins. DNA replication, D. Mutation theory by de Vries
however, copies DNA using DNA polymerases without (A) B → A → D → C
producing or utilizing RNA as a primary template. (B) D → B → A → C
(C) B → D → C → A
15. What best describes the function of a promoter in (D) A → B → C → D
transcription?


Ans
(A) Terminates RNA synthesis
(B) Catalyzes peptide bond formation (A) B → A → D → C
(C) Binds RNA polymerase to initiate gene transcription Lamarck proposed his ideas (early 19th century),
(D) Causes unwinding of the entire DNA molecule Darwin published “On the Origin of Species” in 1859,
de Vries proposed mutation theory in the early 1900s,


Ans
and the modern synthesis integrated genetics with
(C) Binds RNA polymerase to initiate gene transcription natural selection in the mid-20th century.
A promoter is a specific DNA sequence recognized by
RNA polymerase to begin transcription. Its presence 19. Which term describes the body’s defense mechanism
ensures that genes are expressed in a regulated manner involving memory cells and specific antibodies?
at the correct time and cell type. (A) Innate immunity
(B) Passive immunity
16. Which scientist proposed the theory of natural selection (C) Adaptive immunity
alongside Charles Darwin? (D) Mechanical barrier
(A) Alfred Russel Wallace


Ans
(B) Jean-Baptiste Lamarck
(C) Thomas Malthus (C) Adaptive immunity
(D) Hugo de Vries Adaptive immunity depends on lymphocytes
generating specific antibodies or cytotoxic responses.


Ans
It includes immunological memory, enabling a faster,
(A) Alfred Russel Wallace stronger reaction upon subsequent pathogen exposure.
Alfred Russel Wallace independently conceived the This feature distinguishes it from innate immunity,
idea of evolution by natural selection. Darwin and which offers broad, non-specific defense without
Wallace’s joint presentation in 1858 introduced this immunological memory.
groundbreaking theory, fundamentally altering the
scientific understanding of biodiversity and adaptation. 20. Which disease is NOT commonly caused by a pathogen?
(A) Pneumonia
17. Gene flow generally: (B) Ascariasis
(A) Decreases genetic diversity within populations (C) Diabetes mellitus

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page 40 CUET UG Biology

(D) Ringworm

Ans

Ans (B) Cloning vectors replicate DNA; expression vectors

also facilitate protein production
(C) Diabetes mellitus
Cloning vectors function mainly to replicate and
Pneumonia (bacterial or viral), Ascariasis (parasitic
maintain inserted DNA segments. Expression vectors,
worm), and Ringworm (fungal) all involve infectious
in addition to replication elements, contain promoters
organisms. Diabetes mellitus stems from endocrine
and regulatory sequences enabling transcription and
imbalances related to insulin production or response
translation of the inserted gene, leading to protein
and is not caused by a communicable pathogen, making
production in the host organism.
it the exception on this list.
24. Which method is commonly employed to introduce
21. Which step is key in secondary sewage treatment?
recombinant DNA into bacterial cells?
(A) Sedimentation of large debris
(A) Chemical transformation using calcium chloride
(B) Chlorination for disinfection
(B) Gel electrophoresis
(C) Use of activated sludge to biodegrade organic
(C) Northern blotting
matter
(D) Sonication
(D) Adding chemical coagulants for flocculation


Ans


Ans
(A) Chemical transformation using calcium chloride
(C) Use of activated sludge to biodegrade organic matter
Bacterial cells gain competency through calcium
Secondary treatment employs microorganisms in
chloride treatment, rendering their membranes
activated sludge to biodegrade dissolved and suspended
more permeable to external DNA. Subsequent heat
organic contaminants. This process follows primary
shock promotes the plasmid’s passage into cells. This
sedimentation and precedes disinfection. It crucially
straightforward chemical transformation remains
reduces biochemical oxygen demand and pollutant load,
a fundamental technique in genetic engineering
resulting in cleaner effluent for eventual environmental
laboratories.
discharge.
25. What is gene therapy?
22. Which microbe is employed in Swiss cheese production
(A) Identifying species based on DNA fingerprints
for its characteristic large holes?
(B) Replacing a defective gene with a functional copy
(A) Penicillium roqueforti
to treat genetic disorders
(B) Lactobacillus acidophilus
(C) Generating new insect-resistant crops
(C) Propionibacterium shermanii
(D) Cloning animals for experimental studies
(D) Streptococcus thermophilus


Ans


Ans
(B) Replacing a defective gene with a functional copy to
(C) Propionibacterium shermanii
treat genetic disorders
Propionibacterium shermanii ferments lactic acid,
Gene therapy involves delivering normal genes into
producing carbon dioxide that forms the iconic holes in
cells to correct genetic defects or provide new functions.
Swiss cheese. This fermentation contributes a distinct,
It offers potential cures for inherited diseases by fixing
nutty flavor, setting Swiss cheese apart from other
the underlying molecular cause rather than merely
varieties and highlighting the significance of microbial
managing symptoms.
processes in dairy products.
26. Which is an example of a transgenic animal?
23. How do cloning vectors differ from expression vectors
(A) Dolly the sheep cloned by nuclear transfer
in recombinant DNA technology?
(B) A sheep that naturally produces wool
(A) Cloning vectors incorporate large inserts;
(C) A laboratory rat in normal breeding
expression vectors only store small inserts
(D) A cow producing foreign protein in its milk
(B) Cloning vectors replicate DNA; expression vectors
also facilitate protein production

Ans
(C) Both are identical and used interchangeably (D) A cow producing foreign protein in its milk
(D) Expression vectors are used only in prokaryotes,
cloning vectors in eukaryotes

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 PRACTICE PAPER 04

Transgenic animals harbor exogenous genes that (D) (A) is false, (R) is true
enable them to express novel traits. A cow engineered

Ans
to synthesize human proteins in its milk exemplifies
this approach. By introducing foreign DNA, scientists (A) Both (A) and (R) are true, and (R) is the correct
can produce valuable biomolecules for therapeutic explanation of (A)
applications. Predators often target weaker individuals, limiting prey
overpopulation. This regulation can reduce intense
27. Which statements accurately describe population competition among prey species, facilitating coexistence.
attributes? By controlling dominant species, predation can help
I. Birth rate affects population size maintain higher biodiversity within ecosystems.
II. Age distribution remains constant always
30. What is biomass in an ecological context?
III. Death rate influences population growth
IV. Immigration can increase population density (A) Cumulative light energy entering an ecosystem
(A) I, III, and IV (B) Total mass of living organisms in a given area
(B) II and III (C) Total nitrogen content in soil
(C) I and II (D) Quantity of carbon dioxide in the atmosphere
(D) III and IV

Ans


Ans (B) Total mass of living organisms in a given area
(A) I, III, and IV Biomass represents the aggregate weight or organic
Birth rates increase population size, while death rates matter of living organisms within a specified region.
reduce it. Immigration adds individuals to a population, It indicates the potential energy available to higher
raising density. Age distribution fluctuates with factors trophic levels and aids in understanding the ecosystem’s
like fertility, mortality, and migration, making statement productivity and capacity to support various life forms.
II incorrect. Hence, statements I, III, and IV are accurate 31. Arrange the following stages in a typical energy transfer
attributes. through trophic levels:
28. Which is NOT a type of population interaction? A. Tertiary consumer
(A) Predation B. Sunlight capture by producers
(B) Commensalism C. Secondary consumer
(C) Mutualism D. Primary consumer
(D) Metamorphosis (A) B → D → C → A
(B) B → A → C → D


Ans (C) A → B → D → C
(D) Metamorphosis (D) D → B → C → A
Predation, commensalism, and mutualism are distinct

Ans
ecological relationships among different species.
Metamorphosis, however, describes the developmental (A) B → D → C → A
change within a single organism’s life cycle and does Initially, producers capture solar energy through
not involve an interspecific population interaction. photosynthesis. Primary consumers (herbivores)
Therefore, it is not classified among these population consume these plants, secondary consumers
interactions. (carnivores) feed on herbivores, and tertiary consumers
prey on secondary consumers. This progression
29. Assertion (A) : Predation can maintain species diversity reflects the typical unidirectional flow of energy across
in a community. ecosystem trophic levels.
Reason (R) : Predators eliminate weak or excessive prey,
32. Which Indian region is recognized as a biodiversity
preventing competitive exclusion.
(A) Both (A) and (R) are true, and (R) is the correct hotspot?
explanation of (A) (A) Western Ghats
(B) Both (A) and (R) are true, but (R) is not the correct (B) Indo-Gangetic plain
explanation (C) Thar Desert
(C) (A) is true, (R) is false (D) Rann of Kutch

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Ans These hormones collectively regulate various aspects of

(A) Western Ghats human reproduction.
The Western Ghats is internationally recognized as a
35. Match the following genetic terms (Column I) with
biodiversity hotspot, boasting extensive endemism and
their descriptions (Column II):
varied ecosystems. Due to anthropogenic pressures
such as deforestation and land-use changes, it faces Column I Column II
significant conservation challenges. Its rich flora and 1. Multiple alleles A. More than two alleles
fauna underscore its global ecological importance. present for a gene
33. Identify statements about wildlife conservation: 2. Polygenic B. Interaction where one
I. Establishing protected areas (national parks, inheritance gene masks another
sanctuaries) 3. Linkage C. Several genes influence a
II. Encouraging illegal trade of exotic animals single trait
III. Captive breeding programs for endangered species 4. Epistasis D. Genes located on the same
IV. Promoting afforestation and habitat restoration chromosome, inherited
(A) I, II, and III together
(B) I, III, and IV Options:
(C) II, III, and IV (A) 1-A, 2-C, 3-D, 4-B
(D) I and II (B) 1-C, 2-A, 3-B, 4-D


Ans (C) 1-B, 2-D, 3-A, 4-C
(B) I, III, and IV (D) 1-A, 2-B, 3-C, 4-D
Conservation efforts involve protected areas, captive

Ans
breeding, and habitat restoration through reforestation. (A) 1-A, 2-C, 3-D, 4-B
These strategies safeguard habitats and gene pools, Multiple alleles signify more than two variants of a
aiding endangered populations. Facilitating illegal trade, gene, polygenic inheritance involves multiple genes
however, undermines these measures, pushing species determining a trait, linkage is the tendency of genes
closer to extinction and thwarting conservation goals. on the same chromosome to be inherited together, and
34. Match the human reproductive hormones (Column I) epistasis is gene interaction where one locus masks
with their primary sources (Column II): another.

Column I Column II 36. Match the molecular biology techniques (Column I)

1. Estrogen A. Placenta with their purposes (Column II):
2. Progesterone B. Corpus luteum Column I Column II
3. Testosterone C. Growing ovarian follicles 1. PCR A. Separating DNA fragments
4. hCG (Human D. Leydig cells in testes by size
Chorionic 2. Southern B. Amplifying specific DNA
Gonadotropin) blotting segments
Options: 3. DNA C. Detecting particular DNA
(A) 1-C, 2-B, 3-A, 4-D fingerprinting sequences on a membrane
(B) 1-C, 2-B, 3-D, 4-A 4. Gel D. Comparing variable
(C) 1-B, 2-C, 3-D, 4-A electrophoresis regions for individual
(D) 1-D, 2-B, 3-C, 4-A identification


Ans Options:
(B) 1-C, 2-B, 3-D, 4-A (A) 1-B, 2-C, 3-D, 4-A
Estrogen is mainly produced by developing ovarian (B) 1-C, 2-B, 3-A, 4-D
follicles, progesterone by the corpus luteum after (C) 1-B, 2-A, 3-C, 4-D
ovulation, testosterone by Leydig cells in the male (D) 1-D, 2-C, 3-A, 4-B
testes, and hCG by the placenta to support pregnancy.

Ans

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 PRACTICE PAPER 04

(A) 1-B, 2-C, 3-D, 4-A (C) 1-C, 2-B, 3-A, 4-D
PCR amplifies targeted DNA regions exponentially. Bt crops express Cry proteins toxic to certain insect
Southern blotting detects particular DNA sequences on a pests, Golden rice is enriched with provitamin A,
membrane. DNA fingerprinting compares polymorphic gene therapy replaces defective genes in patients, and
regions to establish identity. Gel electrophoresis transgenic animals incorporate foreign DNA to manifest
separates DNA fragments by size, enabling analysis of beneficial traits. These diverse approaches underscore
their distinct banding patterns. biotechnology’s transformative potential.

37. Match the industrial product (Column I) with its 39. Which statements about Hardy-Weinberg principle are
microbial source (Column II): true?
I p + q = 1 for two alleles
Column I Column II
II. Allele frequencies change rapidly without external
1. Ethanol A. Clostridium acetobutylicum factors
2. Butanol B. Saccharomyces cerevisiae III. Large population size is assumed
3. Acetic acid C. Penicillium chrysogenum IV. Random mating is required
4. Antibiotic D. Acetobacter aceti (A) I, III, and IV
Penicillin (B) II and IV
(C) I and II
Options:
(D) I, II, and III
(A) 1-B, 2-D, 3-A, 4-C
(B) 1-B, 2-A, 3-D, 4-C

Ans
(C) 1-D, 2-B, 3-C, 4-A (A) I, III, and IV
(D) 1-A, 2-C, 3-B, 4-D The Hardy-Weinberg principle states p + q = 1 for two


Ans alleles, requires a large population and random mating,
and assumes no mutation, selection, or migration. Allele
(B) 1-B, 2-A, 3-D, 4-C
frequencies remain constant in ideal conditions.
Saccharomyces cerevisiae (yeast) ferments sugars into
ethanol, Clostridium acetobutylicum generates butanol 40. Assertion (A) : A vaccine confers long-lasting immunity
in anaerobic conditions, Acetobacter aceti oxidizes against a specific pathogen.
ethanol to acetic acid, and Penicillium chrysogenum Reason (R) : Vaccines introduce a weakened or dead
produces the antibiotic penicillin. These microbes pathogen, prompting the body to produce memory
underpin various industrial fermentation processes. cells.
(A) Both (A) and (R) are true, and (R) is the correct
38. Match the biotechnology applications (Column I) with
explanation of (A)
their descriptions (Column II):
(B) Both (A) and (R) are true, but (R) is not the correct
Column I Column II explanation
1. Bt crops A. Correcting defective genes (C) (A) is true, (R) is false
in patients (D) (A) is false, (R) is true
2. Golden rice B. Engineered to contain

Ans
provitamin A (A) Both (A) and (R) are true, and (R) is the correct
3. Gene therapy C. Produce Cry toxins against explanation of (A)
insects Vaccines expose the immune system to antigenic
4. Transgenic D. Animals carrying foreign components of a pathogen, eliciting a protective adaptive
animals genes for desired traits response that includes memory cell production. This
Options: confers longer-term defense against subsequent
(A) 1-C, 2-A, 3-B, 4-D infections by the same pathogen.
(B) 1-B, 2-C, 3-A, 4-D

Direction :Carefully read the case study provided and then
(C) 1-C, 2-B, 3-A, 4-D thoroughly answer the subsequent five questions.
(D) 1-A, 2-D, 3-C, 4-B “In a hilly region once teeming with wildlife, deforestation


Ans for timber and farmland expansion led to massive

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habitat fragmentation. Over just two decades, sightings (A) Complete ban on all tree planting
of native deer and several bird species plummeted. Local (B) Introduction of exotic predators
communities dependent on forest resources suffered (C) Establishment of a protected sanctuary and
as water sources dried and soil erosion worsened. reforestation
Environmental researchers, in collaboration with (D) Relocation of local residents
governmental agencies, launched a reforestation drive and

Ans
declared a portion of the area a protected sanctuary. This
initiative involved planting native saplings, restricting (C) Establishment of a protected sanctuary and
unsustainable logging, and educating residents on reforestation
alternative livelihoods. Gradually, water tables improved, Authorities and researchers created a sanctuary to
and signs of wildlife recovery emerged. Students and preserve remaining wildlife while replanting native
volunteers contributed to biodiversity surveys, fostering species. Limiting unsustainable logging and offering
awareness. Ongoing monitoring aims to reinforce alternative livelihoods helped revitalize the forest
conservation gains, ensuring the forest continues to habitat, facilitating wildlife return and stabilizing local
support both local inhabitants and key species. Regional ecosystems.
policy changes limited further commercial exploitation, 44. Who assisted with biodiversity surveys to track wildlife
strengthening habitat protection and community recovery?
involvement.” (A) International security forces
41. Which primary factor led to declining wildlife (B) Students and volunteers
populations in the region? (C) Corporate lobbyists
(A) Excess rainfall (D) Robotic drones only
(B) Habitat fragmentation from deforestation

Ans
(C) Sudden volcanic eruption (B) Students and volunteers
(D) Surplus food resources Community engagement was crucial, with students and


Ans volunteers performing field surveys of returning species.
(B) Habitat fragmentation from deforestation This hands-on approach not only provided valuable
The case highlights deforestation for timber and farmland data on biodiversity recovery but also cultivated broader
as the driving force behind habitat fragmentation. awareness and enduring commitment to protecting the
This disruption isolated wildlife populations, reducing region’s natural habitats.
resources and leading to the decline in species such as 45. What long-term outcome do researchers and locals aim
deer and birds. for?
42. How did habitat loss affect local communities? (A) Rapid industrial expansion
(A) They gained more farmland profits (B) Total exclusion of all visitors
(B) Soil erosion and water shortages impacted (C) Sustainable coexistence between humans and
livelihoods wildlife
(C) Overpopulation occurred in the villages (D) Phasing out all agriculture
(D) No noticeable change was reported

Ans


Ans (C) Sustainable coexistence between humans and
(B) Soil erosion and water shortages impacted wildlife
livelihoods The narrative stresses balancing ecological integrity with
The text states water sources dried up and soil erosion human needs, promoting reforestation and regulated
increased after forest cover vanished. These changes resource use. By strengthening habitat protection and
reduced agricultural productivity and strained daily community engagement, the region aims for long-
life for communities reliant on forest ecosystems for term harmony between human livelihoods and wildlife
resources and stability. populations, ensuring ongoing sustainability.

43. Which conservation strategy was implemented to

Direction :Carefully read the case study provided and then
restore biodiversity? thoroughly answer the subsequent five questions.
“In an urban high school, educators observed a worrying

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 PRACTICE PAPER 04

rise in substance use among teenagers, particularly (B) They replaced teachers in classrooms
alcohol and stimulants. Many students reported stress (C) They promoted supportive, substance-free
from academic competition and found temporary escape environments
in these substances. The school established a dedicated (D) They distributed banned substances for research
wellness program featuring confidential counseling,

Ans
regular health check-ups, and workshops highlighting the
medical and social risks of drug and alcohol abuse. Parents (C) They promoted supportive, substance-free
were also encouraged to attend seminars on early warning environments
signs and effective communication. Over time, peer Peer educators served as role models among students,
educators were trained to foster supportive, substance- advocating healthy activities like sports or arts, and
free environments, offering activities like sports and art facilitating a culture of mutual respect. Their peer-to-
clubs as positive outlets. Collaborations with local health peer approach strengthened trust, diminishing stigma
centers ensured that students struggling with addiction and encouraging healthier choices.
received professional intervention. A subsequent survey 49. Which additional resource supported students with
showed a decline in substance-related incidents, reflecting severe addiction?
the program’s positive influence. Educators continue (A) Mandatory dropouts
adjusting strategies to address emerging substances and (B) Expulsion from school
maintain open communication channels with families.” (C) Collaboration with local health centers for
46. What prompted the wellness program’s creation in the professional intervention
high school? (D) Peer pressuring classmates
(A) Excellent academic performance

Ans
(B) Steady drop in substance misuse (C) Collaboration with local health centers for
(C) Notable increase in student substance abuse professional intervention
(D) Abundance of extracurricular activities The narrative emphasizes partnerships with local health


Ans facilities, allowing students in more severe addiction
(C) Notable increase in student substance abuse stages to access specialized therapy, medical treatment,
The program was established in response to a worrying and rehabilitation. This multi-faceted support system
rise in alcohol and stimulant misuse among teenagers, extended the school’s capacity to effectively assist those
driven by academic pressure and stress. Recognizing the requiring professional interventions.
trend, educators took proactive steps to intervene. 50. What was a reported outcome of the wellness initiative?
47. Which key component aimed to educate parents? (A) Increased academic stress
(A) Free canteen services (B) More instances of drug overdose
(B) Seminars on early warning signs and (C) Decline in substance-related incidents
communication (D) Complete ban on sports activities
(C) Promoting exclusive sports scholarships

Ans
(D) Financial incentives for college (C) Decline in substance-related incidents


Ans A subsequent survey revealed reduced substance abuse
(B) Seminars on early warning signs and communication cases among students, indicating the wellness program’s
Parents were offered seminars on how to spot early signs success. By combining counseling, parental involvement,
of substance misuse and foster proactive conversations peer support, and professional intervention, the
with teenagers. By equipping families with critical initiative effectively mitigated drug and alcohol misuse.
knowledge and communication strategies, the school


*************
ensured continuity of prevention efforts between home
and classroom.

48. How did peer educators contribute to the program’s

success?
(A) They enforced strict punishments

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PRACTICE PAPER 05

1. Which term signifies seed formation without (C) Xenogamy ensuring genetic exchange between
fertilization in certain angiosperms? distinct plants
(A) Parthenocarpy results in seedless fruit development (D) Cleistogamy occurring in closed flowers
without fertilization

Ans
(B) Vivipary involves seed germination within the
parent structure (C) Xenogamy
(C) Polyembryony creates multiple embryos in one Xenogamy is cross-pollination between flowers
seed of different plants belonging to the same species.
(D) Apomixis enables asexual seed formation It increases genetic diversity, promoting healthier
offspring and adaptability. Unlike geitonogamy, which


Ans occurs within the same plant, xenogamy introduces
(D) Apomixis novel gene combinations, enhancing evolutionary
Apomixis is a reproductive mechanism producing seeds potential. This mechanism underpins outbreeding,
without gametic fusion. It preserves parental traits by maintaining population vigor across generations. It
bypassing meiosis and fertilization, ensuring clonal fosters heterozygosity.
propagation. This strategy is beneficial in horticulture,
4. Which hormone primarily triggers ovulation by surging
where desirable characteristics remain stable. It also
reduces genetic diversity, impacting evolutionary around the middle of the menstrual cycle?
adaptability, yet guarantees consistent offspring in (A) Follicle-Stimulating Hormone facilitating follicular
suitable environments. For reproduction. development
(B) Luteinizing Hormone causing rupture of the
2. Which structure in a mature embryo sac typically mature follicle
houses two polar nuclei that fuse with a sperm? (C) Prolactin stimulating milk production postpartum
(A) Antipodal cells located at the chalazal end (D) Oxytocin promoting uterine contractions during
(B) Egg apparatus comprising egg and synergids childbirth
(C) Central cell containing the polar nuclei

Ans
(D) Micropylar canal guiding pollen tube entry
(B) Luteinizing Hormone


Ans A sudden rise in Luteinizing Hormone (LH) around
(C) Central cell day 14 triggers the dominant follicle to release the ovum
The central cell of the embryo sac encloses two polar from the ovary. This event, called ovulation, marks the
nuclei, which unite with one sperm nucleus during transition from the follicular phase to the luteal phase,
double fertilization to form the triploid endosperm. preparing the female reproductive tract for possible
This event supports embryo development by providing fertilization and embryo implantation. It is crucial.
nutrition. The process exemplifies unique angiosperm
5. Consider the following statements about
reproduction, ensuring efficient resource allocation for
the developing seed and embryo overall. spermatogenesis:
1. It begins at puberty under hormonal influence.
3. Which term describes the transfer of pollen grains from 2. Sertoli cells provide nourishment.
an anther to a stigma of a different flower on a separate 3. The process occurs in the epididymis.
plant of the same species? 4. LH stimulates Leydig cells for testosterone
(A) Autogamy referring to self-pollination in a single secretion.
flower Which combination of statements is correct?
(B) Geitonogamy pollinating different flowers on the (A) 1, 2, and 4 only
same plant (B) 1, 3, and 4 only

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 PRACTICE PAPER 05

(C) 2 and 3 only a. Intrauterine i. Surgical procedure on male

(D) 1, 2, and 3 only device (IUD) vas deferens


Ans b. Condom ii. Physical barrier worn on
(A) 1, 2, and 4 only the penis
Spermatogenesis initiates at puberty when hormones c. Oral pill iii. Hormonal preparation
like FSH and LH stimulate testicular activity. Sertoli preventing ovulation
cells within seminiferous tubules nourish developing d. Vasectomy iv. Device placed in the uterus
sperm. LH prompts Leydig cells to produce testosterone, to prevent implantation
essential for sperm maturation. However, the epididymis
Options:
only stores and matures sperm; actual production occurs
(A) a-iv, b-ii, c-iii, d-i
in seminiferous tubules. This distinction is crucial.
(B) a-ii, b-iv, c-i, d-iii
6. Which structure in the male reproductive system stores (C) a-iii, b-i, c-iv, d-ii
sperm, allowing them to mature before ejaculation? (D) a-i, b-iii, c-ii, d-iv
(A) Epididymis providing a site for maturation

Ans
(B) Seminal vesicle producing fructose-rich fluid
(A) a-iv, b-ii, c-iii, d-i
(C) Prostate gland secreting alkaline fluid
Intrauterine devices (IUDs) inhibit fertilization or
(D) Vas deferens transporting sperm to ejaculatory
implantation, condoms act as physical barriers, oral
duct
pills suppress ovulation via hormones, and vasectomy


Ans interrupts the sperm transport pathway by cutting
(A) Epididymis the vas deferens. This matching covers a range of
The epididymis, coiled atop the testis, stores and contraceptive measures addressing different levels of
nurtures sperm cells, granting time for maturation and fertility regulation with distinct strategies. It ensures
motility development. Once fully matured, these sperm prevention.
travel through the vas deferens for eventual release. This
9. Which term describes the diagnostic procedure
period of storage ensures sperm gain optimal fertilizing
involving the extraction of amniotic fluid to check for
capability, maintaining reproductive efficiency in male
fetal abnormalities?
physiology. Interim is key.
(A) Amniocentesis analyzing fetal genetic markers
7. Which of the following events does NOT occur during (B) Tubectomy blocking female fallopian tubes
the luteal phase of the menstrual cycle? (C) Laparoscopy visually inspecting abdominal organs
(A) Progesterone levels rise to prepare endometrium (D) Chorionic villus sampling examining placental
(B) Follicle matures under FSH influence tissue
(C) Corpus luteum forms from the ruptured follicle

Ans
(D) Endometrium thickens for potential implantation
(A) Amniocentesis


Ans Amniocentesis is a prenatal test using amniotic fluid
(B) Follicle matures under FSH influence to detect chromosomal or genetic disorders. A needle
Follicle maturation primarily occurs during the is inserted into the uterus under imaging guidance,
follicular phase, preceding ovulation. After ovulation, extracting fluid containing fetal cells. This technique
the ruptured follicle transforms into the corpus luteum, enables early diagnosis of conditions such as Down’s
secreting progesterone to maintain the endometrium. syndrome, guiding informed decisions about pregnancy
This luteal phase fosters a uterine environment suitable management and clinical intervention effectively.
for implantation. Follicular development is no longer the
10. Which assisted reproductive technology involves
key event at this stage. Hence, progesterone dominates.
transferring an ovum collected from a donor into
8. Match the contraceptive method in Column I with its another woman’s fallopian tube for fertilization?
description in Column II: (A) ZIFT placing zygote in fallopian tube
(B) GIFT placing gametes in fallopian tube
Column I Column II (C) ICSI injecting sperm into an ovum
(D) IVF growing embryos in a lab dish

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Ans cross experiments revealed this fundamental rule.

(B) GIFT placing gametes in fallopian tube When gametes fuse at fertilization, alleles recombine,
Gamete Intra-Fallopian Transfer (GIFT) uses a donor preserving genetic variation and allowing inheritance
ovum and the intended father’s sperm, placing them patterns to manifest predictably across generations.
directly into the recipient’s fallopian tube. Fertilization Ensures continuity.
then occurs naturally within her body. This procedure
13. Which genetic disorder is caused by the presence of an
benefits women who have functional fallopian tubes but
extra chromosome 21?
cannot produce viable ova, providing a viable alternative
(A) Turner’s syndrome with XO genotype
to conventional IVF effectively.
(B) Klinefelter’s syndrome with XXY genotype
11. Match the following genetic terms in Column I with (C) Down’s syndrome with trisomy 21
their correct descriptions in Column II: (D) Thalassemia causing reduced hemoglobin synthesis

Column I Column II

Ans

a. Incomplete i. More than two alternative (C) Down’s syndrome with trisomy 21
dominance forms of a gene Down’s syndrome occurs when an individual
b. Co-dominance ii. Both alleles fully expressed inherits three copies of chromosome 21 instead of
in heterozygotes the usual two. This leads to distinctive facial features,
intellectual disability, and various health complications.
c. Multiple alleles iii. One allele not completely
The condition arises from nondisjunction during
dominant over the other
gametogenesis, highlighting how abnormal chromosome
d. Polygenic iv. Traits controlled by segregation affects growth and development patterns.
inheritance multiple genes Exemplifies meiotic error.
Options:
(A) a-ii, b-iii, c-iv, d-i 14. Match the components in Column I with their function
(B) a-iii, b-ii, c-i, d-iv in Column II regarding the lac operon:
(C) a-iv, b-i, c-ii, d-iii Column I Column II
(D) a-i, b-iv, c-iii, d-ii a. Lac Z i. Codes for


Ans β-galactosidase
(B) a-iii, b-ii, c-i, d-iv b. Lac Y ii. Codes for transacetylase
In incomplete dominance, heterozygotes show c. Lac A iii. Binding site for repressor
intermediate phenotypes, co-dominance expresses d. Operator region iv. Codes for permease
both alleles equally, multiple alleles means more
Options:
than two possible versions of a gene (like ABO blood
(A) a-i, b-iv, c-ii, d-iii
groups), and polygenic inheritance involves multiple
(B) a-iv, b-i, c-ii, d-iii
genes contributing to a single trait. This categorization
(C) a-i, b-ii, c-iv, d-iii
underscores varied genetic mechanisms shaping
(D) a-ii, b-i, c-iv, d-i
phenotypic expression. It highlights complexity.


Ans
12. Which principle explains the separation of alleles during
(A) a-i, b-iv, c-ii, d-iii
gamete formation, as first described by Mendel?
In the lac operon, Lac Z produces β-galactosidase for
(A) Principle of Independent Assortment
lactose hydrolysis, Lac Y produces permease enhancing
(B) Principle of Dominance
lactose uptake, and Lac A produces transacetylase. The
(C) Law of Segregation
operator region binds the repressor protein, controlling
(D) Chromosome Theory of Inheritance
transcription. This operon exemplifies gene regulation


Ans in prokaryotes, responding to lactose availability for
(C) Law of Segregation energy metabolism. It ensures metabolic efficiency.
The Law of Segregation states that allele pairs separate
15. Which experiment by Hershey and Chase confirmed
during gametogenesis, ensuring each gamete carries
DNA, not protein, as the genetic material using
a single allele for each trait. Mendel’s monohybrid
radioactively labeled bacteriophages?

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 PRACTICE PAPER 05

(A) Mice injection experiments by Griffith reproductive success. Genetic drift, however, is a
(B) X-ray diffraction by Franklin random process affecting allele frequencies, especially
(C) T2 phage experiments with sulfur and phosphorus in small populations, and does not consistently favor
labels beneficial traits. Thus, while (A) is correct, the stated
(D) Beadle and Tatum’s Neurospora experiments reason (R) is incorrect. Are independent forces.


Ans 18. Arrange the following events of human evolution in
(C) T2 phage experiments with sulfur and phosphorus correct chronological order:
labels 1. Appearance of Homo habilis
In 1952, Hershey and Chase used radioactive sulfur 2. Emergence of modern Homo sapiens
to label phage proteins and radioactive phosphorus 3. Use of stone tools intensifies
to label phage DNA. After infection of bacteria, only 4. Migration out of Africa
radioactive phosphorus entered bacterial cells, proving (A) 1 → 3 → 4 → 2
DNA carried hereditary information. This pivotal (B) 3 → 1 → 2 → 4
demonstration resolved debates on whether proteins (C) 1 → 2 → 3 → 4
or nucleic acids governed inheritance. Revolutionized (D) 2 → 1 → 4 → 3
molecular biology.

Ans
16. Which process involves the synthesis of RNA from a (A) 1 → 3 → 4 → 2
DNA template inside the nucleus? Homo habilis, known as the “handy man,” appeared
(A) Replication duplicating DNA first, initiating more advanced stone tool use. Over time,
(B) Transcription synthesizing RNA stone tool usage expanded significantly. Early human
(C) Translation assembling polypeptides populations then ventured out of Africa, culminating in
(D) Splicing removing introns the emergence of anatomically modern Homo sapiens.


Ans This sequence reflects major milestones in human
evolution. Shapes our lineage.
(B) Transcription synthesizing RNA
During transcription, RNA polymerase unwinds the 19. Which factor most directly drives adaptive evolution by
DNA helix and builds a complementary RNA strand favoring organisms with heritable traits that enhance
using one DNA strand as the template. This newly survival?
formed mRNA transports genetic information from (A) Gene flow transferring alleles among populations
the nucleus to ribosomes in the cytoplasm. It precedes (B) Mutation introducing novel genetic variants
translation, where the encoded message is converted (C) Natural selection increasing reproductive success
into a polypeptide chain effectively. (D) Genetic drift randomly altering allele frequencies

17. Assertion (A) : Darwin’s theory of natural selection

Ans

suggests that favorable traits increase an organism’s (C) Natural selection increasing reproductive success
chances of survival and reproduction. Natural selection operates on heritable variations,
Reason (R) : Genetic drift always amplifies beneficial favoring individuals that reproduce more successfully.
traits in large populations, ensuring they dominate Over generations, advantageous alleles become more
successive generations. common, refining population traits. Though gene
(A) Both (A) and (R) are true, and (R) is the correct flow, mutation, and genetic drift also shape genetic
explanation of (A) composition, natural selection remains the primary
(B) Both (A) and (R) are true, but (R) is NOT the mechanism linking environmental pressures to adaptive
correct explanation of (A) phenotypic changes. Ensures directional evolutionary
(C) (A) is true, but (R) is false change.
(D) (A) is false, but (R) is true
20. Match each pathogen in Column I with the disease it


Ans causes in Column II:
(C) (A) is true, but (R) is false
Column I Column II
Darwin’s natural selection principle states that
advantageous traits enhance survival, leading to higher a. Plasmodium i. Common cold

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b. Salmonella typhi ii. Filariasis T lymphocytes, particularly cytotoxic T cells, recognize

and destroy cells harboring pathogens. Unlike B
c. Rhinovirus iii. Malaria
lymphocytes that secrete antibodies, T lymphocytes
d. Wuchereria bancrofti iv. Typhoid directly target and kill infected cells. Their cell-mediated
Options: response is vital in controlling viral infections, tumor
(A) a-i, b-ii, c-iv, d-iii surveillance, and coordinating immune functions
(B) a-iii, b-iv, c-i, d-ii alongside other immune cells. Frontline defense
(C) a-ii, b-i, c-iii, d-iv prevents pathogen spread.
(D) a-iv, b-iii, c-ii, d-i
23. Match the following microbial applications in Column I


Ans with their respective uses in Column II:
(B) a-iii, b-iv, c-i, d-ii
Column I Column II
Plasmodium causes malaria, Salmonella typhi leads to
typhoid, Rhinovirus triggers the common cold, and a. Saccharomyces i. Curd formation
Wuchereria bancrofti causes filariasis. Each pathogen cerevisiae
targets humans differently, affecting various organs and b. Acetobacter aceti ii. Ethanol to acetic acid
bodily functions. Understanding their transmission and production
lifecycle is crucial for effective prevention, control, and c. Methanogens iii. Bread fermentation
management of these potentially severe infections. It d. Lactobacillus iv. Biogas production
reduces morbidity.
Options:
21. Which of the following is NOT a symptom commonly (A) a-iii, b-ii, c-iv, d-i
associated with HIV/AIDS progression? (B) a-ii, b-iv, c-i, d-iii
(A) Significant weight loss and persistent fatigue (C) a-i, b-iii, c-ii, d-iv
(B) Multiple opportunistic infections like tuberculosis (D) a-iv, b-i, c-iii, d-ii
(C) Sudden regeneration of T-lymphocytes to high

Ans
levels
(A) a-iii, b-ii, c-iv, d-i
(D) Decline in immune response over time
Saccharomyces cerevisiae (baker’s yeast) ferments


Ans dough, Acetobacter aceti oxidizes ethanol to acetic
(C) Sudden regeneration of T-lymphocytes to high acid (vinegar), methanogens produce biogas (methane)
levels from organic waste, and Lactobacillus converts milk to
HIV/AIDS damages immune cells, especially CD4+ curd. These microbes contribute significantly to food
T-lymphocytes, causing their gradual depletion rather processing, industrial manufacturing, and sustainable
than regeneration. Patients experience recurring energy solutions through biological processes. They
infections and marked weight loss due to weakened demonstrate microbial versatility, boosting human
immunity. The disease progresses as viral replication endeavors.
outpaces immune cell production, ultimately
24. Which microbe is widely employed for the large-scale
compromising the body’s defense against various
production of the antibiotic penicillin?
pathogens and opportunistic diseases. Sudden reversal
(A) Penicillium chrysogenum
occurs.
(B) Aspergillus niger
22. Which is the primary cell-mediated immune response (C) Rhizobium leguminosarum
cell, crucial for killing virus-infected cells? (D) Streptococcus thermophilus
(A) B lymphocytes producing antibodies

Ans
(B) T lymphocytes providing cell-mediated defense
(A) Penicillium chrysogenum
(C) Natural killer cells releasing perforins
Penicillium chrysogenum is a fungus extensively used
(D) Neutrophils performing phagocytosis
in industrial fermenters to synthesize penicillin, the


Ans first widely discovered antibiotic. This drug inhibits
(B) T lymphocytes providing cell-mediated defense bacterial cell wall synthesis, providing a breakthrough
in treating various bacterial infections. The organism’s

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 PRACTICE PAPER 05

fermentation processes have been optimized to (B) Transformation using competent cells
maximize antibiotic yield for clinical applications. It Transformation employs chemical or physical methods,
revolutionized medicine. such as Ca2+ treatment and heat shock, to transiently
permeabilize bacterial cell membranes. This enables
25. Which type of bacterium helps fix atmospheric nitrogen exogenous DNA, like recombinant plasmids, to enter.
in the root nodules of legumes, enhancing soil fertility? After successful uptake, bacteria may exhibit new
(A) Streptococcus pneumoniae traits or antibiotic resistance markers, validating
(B) Rhizobium species the integration of engineered genetic material. It
(C) Clostridium tetani revolutionizes cloning.
(D) Lactobacillus acidophilus
28. Which enzyme is used to form complementary DNA


Ans
(cDNA) from an mRNA template?
(B) Rhizobium species (A) Restriction endonuclease
Rhizobium bacteria form symbiotic relationships (B) DNA ligase
with legumes, colonizing root nodules and converting (C) Reverse transcriptase
atmospheric nitrogen into ammonia. This process, (D) DNA polymerase III
known as biological nitrogen fixation, enriches soil
fertility and reduces the need for chemical fertilizers.

Ans
Plants benefit from readily available nitrogen, while (C) Reverse transcriptase
the bacteria gain carbohydrates and a protective niche. Reverse transcriptase synthesizes DNA from an RNA
Ensures productivity. template, enabling researchers to generate cDNA lacking
introns. This enzyme, originally found in retroviruses,
26. Assertion (A) : Restriction enzymes cut DNA at specific allows scientists to clone eukaryotic genes in prokaryotes
recognition sites, enabling precise gene manipulation. for protein expression. By converting mature mRNA
Reason (R) : Ligases degrade DNA fragments once into DNA, researchers can bypass transcriptional
restriction digestion is complete. complexities and directly study expressed sequences.
(A) Both (A) and (R) are true, and (R) is the correct Facilitates study.
explanation of (A)
(B) Both (A) and (R) are true, but (R) is NOT the 29. Which gene was introduced into Bt cotton to confer
correct explanation of (A) resistance against bollworm pests?
(C) (A) is true, but (R) is false (A) cryIAc from Bacillus thuringiensis
(D) (A) is false, but (R) is true (B) glyphosate-resistant gene from Agrobacterium


Ans (C) bar gene for herbicide tolerance
(D) lacZ gene from Escherichia coli
(C) (A) is true, but (R) is false
Restriction enzymes cleave DNA at specific sequences,

Ans
forming fragments useful for genetic engineering. (A) cryIAc from Bacillus thuringiensis
Ligases perform the opposite function, joining DNA The cryIAc gene codes for a toxin produced by Bacillus
strands, not degrading them. Thus, while restriction thuringiensis that targets specific insect larvae, including
enzymes and ligases act sequentially in recombinant bollworms. Transferring this gene into cotton plants
DNA technology, the reason statement contradicts the imparts pest resistance, reducing chemical insecticide
ligases’ actual role of bonding DNA ends. Collaboration usage. The Bt toxin selectively harms the pest’s gut
is essential. lining, safeguarding the crop while minimally affecting
beneficial organisms. Approach is eco-friendly.
27. Which step in recombinant DNA technology uses
calcium ions and rapid temperature changes to facilitate 30. Which therapy involves correcting genetic disorders by
DNA uptake by bacteria? introducing a functional gene into a patient’s cells?
(A) Ligation with DNA ligase (A) Gene therapy
(B) Transformation using competent cells (B) Chemotherapy
(C) Isolation of plasmid and gene of interest (C) Radiation therapy
(D) Screening through antibiotic markers (D) Immunotherapy


Ans

Ans

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page 52 CUET UG Biology

(A) Gene therapy (C) Biotic potential

Gene therapy targets defective genes by delivering (D) Natality rate
healthy copies via viral or non-viral vectors into affected

Ans
tissues. This approach aims to restore normal protein
function, treating hereditary diseases at their root cause. (B) Carrying capacity
Although still evolving, gene therapy promises more Carrying capacity represents the upper limit of a
precise and lasting solutions compared to symptom- population that a given habitat can sustain, dictated by
focused treatments. Heralds personalized medicine. resource availability, competition, and environmental
constraints. When populations approach or exceed
31. Which is NOT a potential concern regarding transgenic this threshold, resource depletion increases mortality
organisms? or reduces birth rates. This concept shapes ecological
(A) Possible unintended harm to non-target species management and conservation strategies worldwide.
(B) Emergence of resistant pests or pathogens Informs sustainable usage.
(C) Enhanced genetic diversity among local populations
34. Which statement best distinguishes predation from
(D) Ethical and biosafety considerations
parasitism in population interactions?


Ans (A) Predators require a living host, while parasites do
(C) Enhanced genetic diversity among local populations not
Transgenic organisms sometimes pose ecological or (B) Predators typically kill prey quickly, while parasites
ethical issues, including non-target impacts, resistance often keep hosts alive
development, and intellectual property disputes. They (C) Parasites are larger than their hosts, while predators
usually do not increase genetic diversity locally; instead, are always smaller
uniform transgenic traits can reduce variability. Debates (D) Both interactions benefit the victim species
focus on balancing technological benefits with long-

Ans
term environmental stability and respecting societal
values. Ensuring safety remains a priority. (B) Predators typically kill prey quickly, while parasites
often keep hosts alive
32. Which population interaction describes a relationship Predation involves a predator killing and consuming its
where both species benefit from each other’s presence? prey, providing an immediate energy source. Parasitism
(A) Commensalism one species benefits, other relies on a living host for nutrients, so parasites generally
unaffected avoid killing the host quickly to prolong resource access.
(B) Parasitism one species lives at host’s expense These divergent strategies highlight unique ecological
(C) Mutualism both species benefit roles and distinct impacts on population dynamics.
(D) Competition both species negatively affected Underscore evolutionary adaptations.


Ans 35. Which ecological pyramid best illustrates the
(C) Mutualism both species benefit distribution of energy across trophic levels?
Mutualism involves cooperative interactions that (A) Pyramid of numbers
enhance survival or reproduction of both partners. (B) Pyramid of biomass
Classic examples include pollinators and flowering (C) Pyramid of energy
plants, where insects gain food while aiding plant (D) Inverted pyramid of numbers
reproduction. This interaction fosters evolutionary

Ans
interdependence, promoting specialized adaptations.
Unlike commensalism, parasitism, or competition, (C) Pyramid of energy
mutualism yields net advantages for all participating A pyramid of energy depicts the flow of energy through
organisms. Synergy is crucial. each trophic level, always upright because energy is
lost as heat or metabolic activity at every transfer. It
33. Which term denotes the maximum number of highlights the diminishing availability of energy from
individuals of a species that an environment can support producers to top consumers, reflecting ecological
over time? efficiency and limiting food chain length. Model shows
(A) Population density constraints.
(B) Carrying capacity

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 PRACTICE PAPER 05

36. Which term describes the total rate of photosynthesis Biodiversity hotspots are areas with remarkable endemic
in a given area, excluding the energy used in plant species facing significant habitat loss. India’s Western
respiration? Ghats harbor diverse flora and fauna found nowhere
(A) Gross primary productivity else, yet face deforestation, climate change, and human
(B) Net primary productivity encroachment. Their designation emphasizes urgent
(C) Secondary productivity conservation efforts to protect irreplaceable genetic
(D) Tertiary productivity resources and maintain regional ecological balance.


Ans Them remains critical.

(B) Net primary productivity 39. Which of the following is NOT a strategy for biodiversity
Net primary productivity (NPP) equals gross primary conservation?
productivity (the total photosynthetic output) minus the (A) Establishing protected areas like national parks
energy plants respire for maintenance. It measures the (B) Promoting habitat fragmentation for species
actual biomass available to consumers and reflects the isolation
energy flow into higher trophic levels. NPP underpins (C) Enforcing laws against poaching and illegal trade
ecosystem functioning, influencing food chain (D) Encouraging in-situ and ex-situ conservation
dynamics and carbon sequestration. Drives ecological

Ans
balance.
(B) Promoting habitat fragmentation for species
37. Read the statements about decomposition: isolation
1. It releases inorganic nutrients. Biodiversity conservation thrives on habitat connectivity,
2. Humification accumulates a dark, amorphous safeguarding entire ecosystems. Fragmentation disrupts
substance. breeding, reduces genetic flow, and heightens species
3. It occurs only in aerobic conditions. vulnerability. Protected areas, legal protection, and both
4. Earthworms accelerate decomposition. in-situ (natural habitats) and ex-situ (zoos, seed banks)
Which combination of statements is correct? initiatives help maintain viable populations and genetic
(A) 1, 2, and 4 only diversity, ensuring long-term ecological resilience.
(B) 2, 3, and 4 only Habitat continuity underpins ecosystem stability.
(C) 1 and 3 only
40. Arrange these conservation efforts in chronological
(D) 1 and 2 only
order of their establishment:


Ans 1. Silent Valley National Park in Kerala
(A) 1, 2, and 4 only 2. Jim Corbett National Park in Uttarakhand
Decomposition liberates inorganic nutrients, essential 3. Project Tiger in India
for nutrient cycling, and forms humus through 4. Kaziranga National Park in Assam
humification. Earthworms (detritivores) boost (A) 2 → 4 → 3 → 1
decomposition by fragmenting organic matter. While (B) 4 → 2 → 3 → 1
aerobic conditions generally speed the process, some (C) 2 → 3 → 4 → 1
decomposition can occur anaerobically. Thus, statements (D) 3 → 2 → 1 → 4
1, 2, and 4 accurately describe decomposition, while

Ans
statement 3 is not universally true overall.
(A) 2 → 4 → 3 → 1
38. Which region is designated as a “biodiversity hotspot” Jim Corbett National Park (1936) is the oldest.
due to its exceptional species richness and high Kaziranga National Park gained official status in 1974.
endemism under threat? Project Tiger launched in 1973 as a nationwide initiative
(A) Amazon Rainforest for tiger conservation. Silent Valley National Park
(B) Western Ghats was established in 1984. Chronological knowledge of
(C) Antarctica these milestones reflects India’s evolving conservation
(D) Siberian Taiga priorities. These efforts guide actions.


Ans

Direction :Carefully read the case study provided and then
(B) Western Ghats thoroughly answer the subsequent five questions.

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Amrita, a 20-year-old college student, began experiencing block microbes, these pills neither stop fluid exchange
irregular menstrual cycles and severe discomfort each nor shield mucosal surfaces. Consequently, sexually
month. Concerned, she visited a gynecologist who transmitted infections can still spread, underscoring
explained that hormonal imbalances could disrupt the importance of barrier methods. This distinction
the menstrual cycle’s phases, affecting ovulation and prevents misconception.
endometrial thickening. The doctor also discussed the
43. Which statement best explains the role of oral
importance of balanced nutrition and stress management
in regulating hormones. Since Amrita wished to contraceptive pills in preventing pregnancy for Amrita?
avoid pregnancy, she opted for an oral contraceptive (A) They destroy all ovarian follicles
pill containing synthetic hormones. The gynecologist (B) They block the uterine lining from thickening
emphasized that oral contraceptives prevent ovulation but (C) They inhibit ovulation via synthetic hormones
do not safeguard against sexually transmitted infections. (D) They dissolve the implanted embryo
They also discussed other contraception methods like

Ans
condoms, which offer barrier protection. Additionally, (C) They inhibit ovulation via synthetic hormones
Amrita was informed about medical termination Oral contraceptive pills typically contain synthetic
of pregnancy (MTP) as a legal option under specific estrogen and progesterone, which suppress the release
conditions, highlighting the necessity of professional of FSH and LH, preventing follicle maturation and
guidance. She realized that comprehensive understanding ovulation. Without ovulation, no egg is available for
of reproductive health empowers informed decisions. fertilization. This hormonal strategy ensures effective
41. Which factor primarily disrupted Amrita’s menstrual pregnancy prevention, provided the user adheres to
cycle according to the doctor? the prescribed regimen consistently. Hinges on correct
(A) Excessive carbohydrate intake only usage.
(B) Genetic alterations in gonadotropins 44. What additional advantage do condoms have over oral
(C) Hormonal imbalance affecting cycle regulation contraceptives, as described in the scenario?
(D) Viral infections affecting ovarian tissue (A) They maintain hormonal balance


Ans (B) They stimulate ovulation
(C) Hormonal imbalance affecting cycle regulation (C) They provide barrier protection against STIs
Hormonal imbalances can alter gonadotropin release, (D) They speed up the menstrual cycle phases
disturbing ovulation and endometrial buildup. The

Ans
doctor highlighted that factors like stress or poor (C) They provide barrier protection against STIs
nutrition further disrupt endocrine signals, causing Condoms physically prevent contact between bodily
irregularities. By addressing these influences, menstrual fluids, reducing the risk of transmitting pathogens like
rhythm can be restored, underscoring how hormone HIV or gonorrhea. In contrast, oral contraceptives
homeostasis is crucial for a stable menstrual cycle. regulate only ovulation and do not shield mucosal
Ensures reproductive health. surfaces. The dual function of condoms in preventing
42. Why did the gynecologist emphasize that oral pregnancy and blocking infection transfer makes them
contraceptives do NOT prevent sexually transmitted vital in comprehensive reproductive health. Efforts.
infections? 45. Why is professional guidance crucial when considering
(A) They target bacterial infections only Medical Termination of Pregnancy (MTP)?
(B) They do not provide a physical barrier (A) It is only needed for minors
(C) They enhance viral transmission (B) Legal and medical aspects require expert assessment
(D) They reduce hormone levels, increasing infection (C) It guarantees permanent sterilization
risk (D) It must involve hormone therapy


Ans

Ans
(B) They do not provide a physical barrier (B) Legal and medical aspects require expert assessment
Oral contraceptives function by regulating hormones to MTP involves both legal parameters and health
prevent ovulation, but they lack any barrier mechanism implications, demanding a qualified practitioner’s
against pathogens. Unlike condoms, which physically evaluation. Potential complications, gestational limits,

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 PRACTICE PAPER 05

and the woman’s overall condition must be assessed. (C) To enable β-carotene biosynthesis in the endosperm
Ensuring safe procedures, counseling on future fertility, The daffodil and bacterial genes encode enzymes
and psychological support underscores the necessity of missing in rice endosperm, catalyzing the metabolic
medical oversight. Professional intervention safeguards pathway for β-carotene production. By incorporating
patient well-being throughout the process effectively. these genes, researchers bridged the biochemical gap
preventing carotenoid synthesis in traditional rice. As


Direction :Carefully read the case study provided and then a result, Golden Rice endosperm gained the ability to
thoroughly answer the subsequent five questions. accumulate provitamin A content. Innovation aids
Dr. Ramesh’s research team aimed to develop a transgenic nutrition.
rice variety enriched with vitamin A. Conventional
rice lacked sufficient β-carotene in its endosperm. By 48. Which concern did critics primarily raise about
introducing genes from daffodil and a bacterium, they transgenic Golden Rice in the case study?
successfully engineered ‘Golden Rice’ to accumulate (A) Insufficient yield under ideal conditions
provitamin A. During field trials, they monitored (B) Potential monopolization and ecological risks
crop performance and potential environmental risks, (C) Immediate toxicity to consumers
including gene flow to wild relatives. While the results (D) Complete resistance to all pests
were promising, they noted public hesitation concerning

Ans
genetically modified organisms (GMOs). Critics cited
concerns over biosafety, long-term impacts on ecosystems, (B) Potential monopolization and ecological risks
and possible monopolization by large biotech firms. Public reservations centered on possible corporate
Nevertheless, the team emphasized that Golden Rice could control limiting farmers’ access, along with uncertainties
combat vitamin A deficiency in vulnerable populations. about gene flow to wild or weedy relatives. Critics worried
Ongoing studies sought to balance scientific innovation, about unforeseen ecological shifts and reliance on
environmental caution, and ethical considerations, patented technology. These apprehensions underscore
highlighting responsible research in agricultural how societal and environmental considerations factor
biotechnology. Further collaborations with regulatory into debates over genetically modified crop adoption.
bodies were planned to ensure safety. Benefits remains challenging.

49. How does Golden Rice primarily address vitamin A

46. Which nutrient was specifically targeted for
enhancement in Golden Rice research? deficiency?
(A) Iron for blood health (A) It replaces all other dietary sources
(B) Vitamin A precursor β-carotene (B) By storing large amounts of vitamin D
(C) Vitamin C for immunological benefits (C) Through β-carotene accumulation in its grains
(D) Zinc for enzymatic functions (D) Using external vitamin A sprays on leaves

Ans

Ans

(B) Vitamin A precursor β-carotene (C) Through β-carotene accumulation in its grains
Golden Rice was engineered to synthesize β-carotene in Golden Rice’s grains contain elevated β-carotene, a
the endosperm, a precursor of vitamin A. Conventional precursor to vitamin A. When humans consume these
rice lacks this compound in meaningful amounts. grains, their bodies convert β-carotene into vitamin A,
Addressing vitamin A deficiency can help prevent mitigating deficiencies. Unlike external supplements
conditions like night blindness. By targeting β-carotene, or fortification, the built-in trait allows regular
researchers aimed to improve the nutritional quality of consumption of a staple food, simplifying distribution
staple foods for vulnerable populations. and potentially reducing deficiency in underserved
populations effectively.
47. Why did Dr. Ramesh’s team introduce genes from
50. Which broader theme emerges from Dr. Ramesh’s
daffodil and a bacterium into rice?
(A) To increase iron absorption Golden Rice trials, as highlighted in the passage?
(B) To boost photosynthetic rate (A) Complete eradication of pesticide use
(C) To enable β-carotene biosynthesis in the endosperm (B) Unrealistic yield targets in biotech crops
(D) To reduce water requirements (C) Balancing innovation with biosafety and ethics
(D) Mandatory vegetarian diets for all consumers


Ans

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Ans
(C) Balancing innovation with biosafety and ethics
Golden Rice exemplifies how scientific breakthroughs
can tackle nutritional challenges, yet must address
environmental sustainability, regulatory oversight, and
fair access. Researchers must weigh potential ecological
repercussions, public apprehensions, and intellectual
property issues against the promise of enhanced
nutrition. This intersection of technology, safety, and
equity underlies modern agricultural biotechnology
universally.

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 PRACTICE PAPER 06

PRACTICE PAPER 06

1. Which process in angiosperms involves two male enclosed seeds. The ovules inside become seeds, while
gametes fusing with different cells in the embryo sac? the ovary wall thickens or modifies into various fruit
(A) Triple fusion types. This transformation is an evolutionary adaptation
(B) Syngamy for spreading offspring and ensuring angiosperm
(C) Double fertilization reproductive success.
(D) Parthenogenesis
4. Which cells in the testes secrete testosterone, influencing


Ans male secondary sexual characteristics?
(C) Double fertilization (A) Sertoli cells
In angiosperms, one male gamete fuses with the egg cell (B) Leydig cells
to form the zygote, while the other unites with the polar (C) Spermatogonia
nuclei to form the triploid endosperm. This dual event (D) Epididymal cells
is unique to flowering plants and ensures both embryo

Ans
and endosperm develop synchronously, optimizing
seed formation for successful reproduction. (B) Leydig cells
Leydig cells, located in the interstitial tissue of the testes,
2. Which term best describes pollination within the same produce testosterone under Luteinizing Hormone
flower, allowing the pollen to land on the stigma of that stimulation. Testosterone controls spermatogenesis,
flower itself? maintains secondary sex traits, and regulates libido.
(A) Geitonogamy By contrast, Sertoli cells provide nutritional support
(B) Xenogamy to developing sperm, demonstrating how distinct cell
(C) Autogamy types coordinate male reproductive physiology.
(D) Cleistogamy
5. Which of the following does NOT directly participate in


Ans nourishing or regulating sperm maturation?
(C) Autogamy (A) Sertoli cells lining seminiferous tubules
Autogamy refers to self-pollination within a single (B) Leydig cells secreting testosterone
flower, where anther and stigma are in proximity. While (C) Bulbourethral glands adding lubrication
it ensures reproduction in the absence of pollinators, it (D) Seminal vesicles contributing fructose-rich fluid
restricts genetic variation. Certain floral adaptations,

Ans
such as synchronized anther-stigma maturity, facilitate
this process, reinforcing species survival under (C) Bulbourethral glands adding lubrication
suboptimal pollinator conditions or isolation. While Sertoli cells directly foster sperm development,
Leydig cells produce essential testosterone, and seminal
3. In seed formation, which structure typically develops vesicles supply nutrient fluid. Bulbourethral glands
into the fruit? mainly secrete mucus for lubrication during ejaculation,
(A) Ovule integuments not directly nourishing sperm. Thus, they do not
(B) Ovary wall significantly influence sperm maturation or viability
(C) Style and stigma compared to the other structures mentioned.
(D) Funiculus attachment
6. During which phase of the menstrual cycle is the


Ans corpus luteum most active, secreting high levels of
(B) Ovary wall progesterone?
After fertilization, the ovary matures into the fruit, (A) Follicular phase
providing protection and aiding dispersal of the (B) Ovulatory phase

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(C) Menstrual phase 9. Which of the following best helps prevent unintended
(D) Luteal phase pregnancies and STIs simultaneously?


Ans (A) Oral contraceptive pills
(B) Contraceptive injectables
(D) Luteal phase (C) Condoms
Following ovulation, the ruptured follicle transforms (D) Intrauterine devices
into the corpus luteum, releasing progesterone to
maintain the endometrial lining. This luteal phase

Ans
prepares the uterus for potential embryo implantation. (C) Condoms
If fertilization doesn’t occur, corpus luteum regression Condoms offer dual protection by physically blocking
leads to decreased hormonal levels and the onset of sperm entry and preventing direct contact with bodily
menstruation, resetting the cycle. fluids that transmit pathogens. Other methods like
pills or injectables are effective for contraception but
7. Consider these statements about human oogenesis: lack STI shielding. Thus, condoms remain essential
1. Primary oocytes form during fetal development. for comprehensive protection against both unwanted
2. Each menstrual cycle releases multiple ova typically. pregnancies and sexually transmitted infections.
3. Secondary oocyte completes meiosis II after
fertilization. 10. Assertion (A) : Assisted Reproductive Technologies
4. Oogonia persist dividing throughout a woman’s (ART) like IVF are recommended for couples with
life. infertility issues.
Which combination of statements is correct? Reason (R) : ART guarantees successful pregnancy in
(A) 1 and 2 only every attempt.
(B) 1 and 3 only (A) Both (A) and (R) are true, and (R) is the correct
(C) 2, 3, and 4 only explanation of (A)
(D) 1, 3, and 4 only (B) Both (A) and (R) are true, but (R) is NOT the


Ans correct explanation of (A)
(C) (A) is true, but (R) is false
(B) 1 and 3 only (D) (A) is false, but (R) is true
Primary oocytes are formed prenatally, arresting in
prophase I until puberty. Each cycle typically releases a

Ans
single ovum. The secondary oocyte completes meiosis (C) (A) is true, but (R) is false
II only upon sperm entry. Oogonia do not continually ART, such as IVF, can assist couples facing infertility
divide postnatally. Hence, statements 1 and 3 reflect by retrieving gametes and fertilizing them outside the
correct aspects of human oogenesis. body. However, success rates vary, influenced by factors
like maternal age or underlying conditions. It does not
8. Which STD is primarily caused by Treponema pallidum guarantee pregnancy each time. Proper counseling and
and can manifest as chancres in early stages? medical evaluations are vital for realistic expectations.
(A) Gonorrhea
(B) Chlamydia 11. Which term describes a cross that examines the
(C) Syphilis inheritance of two traits simultaneously, as performed
(D) Genital herpes by Mendel with pea plants?


Ans (A) Monohybrid cross
(B) Dihybrid cross
(C) Syphilis (C) Reciprocal cross
Treponema pallidum, a spirochete bacterium, causes (D) Test cross
syphilis, often presenting with a painless ulcer (chancre)
initially. If untreated, the infection can progress

Ans
through multiple stages, potentially damaging internal (B) Dihybrid cross
organs. Early diagnosis and antibiotic treatment are Mendel’s dihybrid cross tracked the inheritance of two
critical for managing the disease and preventing severe traits (e.g., seed shape and seed color) in pea plants. He
complications in reproductive and overall health. established the Principle of Independent Assortment,
showing that alleles of different genes segregate

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 PRACTICE PAPER 06

independently. This approach revealed how multiple prokaryotes.

traits could combine in offspring, forming various 3. Okazaki fragments form on the leading strand.
phenotypic combinations. 4. Helicases unwind the DNA double helix.
Which combination of statements is correct?
12. A person with blood group AB exhibits which (A) 1, 2, and 3 only
inheritance pattern for the ABO locus? (B) 1, 2, and 4 only
(A) Incomplete dominance (C) 2, 3, and 4 only
(B) Co-dominance (D) 1 and 4 only
(C) Complete dominance
(D) Multiple allelism without co-dominance

Ans

Ans (B) 1, 2, and 4 only

DNA replication is semi-conservative, each new
(B) Co-dominance molecule retaining one parental strand. In prokaryotes,
Individuals with blood group AB express both A and replication begins at a single origin and moves in two
B antigens equally on red blood cells. Neither allele is directions. Helicases separate the strands. Okazaki
recessive; both manifest their respective antigens fully. fragments, however, form on the lagging strand, not the
This exemplifies co-dominance, in which heterozygotes leading strand. Thus, statements 1, 2, and 4 are valid.
display phenotypes contributed by both alleles
simultaneously, reflecting a crucial exception to classical 15. Which part of a eukaryotic gene is removed during RNA
Mendelian dominance. processing, resulting in the final mRNA sequence?
(A) Exons
13. Match the following genetic disorders in Column I with (B) Introns
their key features in Column II: (C) Promoter regions
Column I Column II (D) 5’ UTR
a. Haemophilia i. XO genotype in females

Ans
b. Thalassemia ii. Reduced hemoglobin (B) Introns
chain synthesis Eukaryotic genes often contain coding exons and
c. Turner’s iii. X-linked recessive noncoding introns. During RNA processing, introns
syndrome bleeding disorder are spliced out, while exons are joined to form mature
d. Klinefelter’s iv. XXY genotype in males mRNA. This splicing step increases versatility of gene
syndrome expression. The final mRNA then carries the coding
information to ribosomes for translation into a
Options:
functional polypeptide.
(A) a-iv, b-iii, c-ii, d-i
(B) a-iii, b-ii, c-i, d-iv 16. Who proposed the “one gene-one enzyme” hypothesis,
(C) a-i, b-iv, c-iii, d-ii later refined to “one gene-one polypeptide”?
(D) a-ii, b-i, c-iv, d-iii (A) Hershey and Chase


Ans (B) Watson and Crick
(C) Beadle and Tatum
(B) a-iii, b-ii, c-i, d-iv
(D) Meselson and Stahl
Haemophilia is an X-linked bleeding disorder,
thalassemia involves defective hemoglobin synthesis,

Ans
Turner’s syndrome shows an XO female karyotype, and (C) Beadle and Tatum
Klinefelter’s syndrome is characterized by an XXY male Through experiments on Neurospora crassa, George
genotype. This matching highlights how chromosomal Beadle and Edward Tatum demonstrated that specific
or molecular abnormalities cause distinct clinical genes govern particular enzymes in metabolic pathways.
manifestations in human genetics. Their “one gene-one enzyme” concept evolved into “one
gene-one polypeptide,” recognizing that some enzymes
14. Read the following statements regarding DNA
have multiple polypeptide subunits and genes can
replication:
encode proteins that aren’t strictly enzymatic.
1. It is semi-conservative.
2. It proceeds bidirectionally from the origin in

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17. Arrange these epochs/events in the correct chronological (B) Punctuated equilibrium
sequence regarding life’s history: Proposed by Niles Eldredge and Stephen Jay Gould,
1. Origin of prokaryotes punctuated equilibrium suggests species remain
2. Appearance of multicellular organisms relatively stable over extended intervals, experiencing
3. Origin of eukaryotes rapid changes in short evolutionary bursts. This
4. Colonization of land by plants contrasts with Darwinian gradualism, which posits
(A) 1 → 3 → 2 → 4 slow, continuous transformations. The fossil record
(B) 2 → 1 → 3 → 4 sometimes shows abrupt appearances, lending support
(C) 3 → 1 → 4 → 2 to this alternate model.
(D) 1 → 2 → 3 → 4
20. Which organism does NOT typically cause a vector-


Ans borne disease in humans?
(A) 1 → 3 → 2 → 4 (A) Plasmodium transmitted by Anopheles mosquitoes
Early life began with prokaryotes, eventually giving (B) Wuchereria bancrofti spread by Culex mosquitoes
rise to eukaryotic cells with organelles. Multicellular (C) Entamoeba histolytica spread via contaminated
organisms developed later, leading to diverse forms in water
aquatic environments. Finally, plants conquered land, (D) Leishmania donovani transmitted by sand flies
drastically altering terrestrial ecosystems. This timeline

Ans
underscores progressive complexity in life’s evolutionary
trajectory on Earth. (C) Entamoeba histolytica spread via contaminated
water
18. How does genetic drift differ from gene flow in shaping Entamoeba histolytica causes amoebiasis by fecal-oral
population genetics? transmission, often through contaminated food or water,
(A) Genetic drift is directional, while gene flow is not via a biological vector. In contrast, Plasmodium,
random Wuchereria bancrofti, and Leishmania donovani each
(B) Genetic drift involves deliberate migration, while rely on specific insect vectors. Understanding different
gene flow is accidental transmission routes helps guide effective prevention
(C) Genetic drift is random fluctuation in allele and control measures for parasitic diseases.
frequencies, while gene flow is movement of alleles
21. Match each pathogen in Column I with its associated
between populations
(D) Genetic drift only occurs in large populations, disease in Column II:
while gene flow only occurs in small populations Column I Column II


Ans a. HIV i. Ascariasis
b. Mycobacterium ii. Acquired Immunodeficiency
(C) Genetic drift is random fluctuation in allele
tuberculosis Syndrome
frequencies, while gene flow is movement of alleles
c. Ascaris iii. Tuberculosis
between populations lumbricoides
Genetic drift arises from chance events affecting allele
d. Hepatitis B virus iv. Viral infection of the liver
frequencies, most pronounced in small populations.
Gene flow involves exchange of genetic material Options:
among populations via migration or interbreeding. (A) a-iii, b-ii, c-iv, d-i
Both mechanisms shift allele distribution but differ (B) a-ii, b-iii, c-i, d-iv
fundamentally in origin: drift is random sampling, while (C) a-iv, b-i, c-ii, d-iii
flow depends on individuals dispersing between groups. (D) a-i, b-iv, c-iii, d-ii


Ans
19. Which evolutionary concept posits that rapid bursts of
speciation occur followed by long periods of stasis? (B) a-ii, b-iii, c-i, d-iv
(A) Gradualism HIV causes AIDS, Mycobacterium tuberculosis causes
(B) Punctuated equilibrium tuberculosis, Ascaris lumbricoides causes ascariasis,
(C) Convergent evolution and Hepatitis B virus infects the liver. Differentiating
(D) Divergent evolution these etiological agents ensures proper diagnosis and
therapy. Each pathogen has unique life cycles, modes of


Ans

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 PRACTICE PAPER 06

transmission, and pathological effects, guiding targeted industrial effluents. This eco-friendly strategy leverages
prevention strategies. biological processes to remove environmental hazards,
highlighting synergy between microbial metabolism
22. Which immune response primarily involves B-cells and ecological recovery.
producing specific antibodies against pathogens?
(A) Cell-mediated immunity 25. Read the statements about microbe-based sewage
(B) Inflammatory response treatment:
(C) Humoral immunity 1. Primary treatment removes large debris through
(D) Innate nonspecific defense filtration.


Ans 2. Secondary treatment uses aerobic microbes to
degrade organic matter.
(C) Humoral immunity 3. Activated sludge contains helpful bacteria.
Humoral immunity entails B-lymphocytes recognizing 4. Tertiary treatment always uses ultraviolet radiation.
antigens and differentiating into plasma cells that Which combination of statements is correct?
secrete antibodies. These antibodies circulate in blood (A) 1, 2, and 3 only
and lymph, neutralizing or marking pathogens for (B) 2, 3, and 4 only
destruction. Conversely, T-cells mediate cell-based (C) 1, 3, and 4 only
responses. Together, humoral and cell-mediated (D) 1, 2, and 4 only
immunity form the adaptive immune system, enabling
highly specific pathogen defense.

Ans
(A) 1, 2, and 3 only
23. Which industrially significant microbe is primarily Primary treatment physically removes solids, while
involved in the ripening of Swiss cheese, creating secondary treatment uses aerobic microorganisms to
characteristic holes? digest organic pollutants. Activated sludge is rich in
(A) Penicillium roqueforti beneficial microbes, enhancing waste decomposition.
(B) Aspergillus oryzae Tertiary treatments can vary (chemical or advanced
(C) Propionibacterium shermanii filtration), not necessarily ultraviolet radiation
(D) Rhizopus stolonifer exclusively. Therefore, statements 1, 2, and 3 accurately


Ans describe key steps.
(C) Propionibacterium shermanii 26. Assertion (A) : A plasmid can act as a vector to transfer
Propionibacterium shermanii ferments lactic acid to foreign DNA into a host cell.
produce carbon dioxide, forming the typical “eyes” or Reason (R) : Plasmids degrade all foreign DNA upon
holes in Swiss cheese. Different cheeses rely on specific entry, preventing recombinant formation.
microbes for distinct flavors, textures, and appearances. (A) Both (A) and (R) are true, and (R) is the correct
Microbial actions in cheese-making exemplify explanation of (A)
controlled fermentations crucial to food processing and (B) Both (A) and (R) are true, but (R) is NOT the
culinary diversity worldwide. correct explanation of (A)
24. Which process involves using living organisms to (C) (A) is true, but (R) is false
degrade harmful substances, such as oil spills or (D) (A) is false, but (R) is true
industrial waste?

Ans
(A) Biomagnification (C) (A) is true, but (R) is false
(B) Bioremediation Plasmids serve as cloning vectors, carrying foreign
(C) Pasteurization DNA segments into competent bacterial cells. They
(D) Pyrolysis do not degrade incoming DNA; instead, they replicate


Ans it. By inserting a gene of interest into a plasmid and
(B) Bioremediation transforming bacteria, scientists obtain multiple copies
Bioremediation employs microorganisms or plants to of recombinant constructs for protein expression or
break down pollutants into less toxic forms, restoring genetic analysis.
contaminated sites naturally. Certain bacteria digest
hydrocarbons in oil spills, while others metabolize

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27. Which process describes sorting transformed cells spontaneously increase biodiversity. In fact, uniform
from non-transformed ones using antibiotic resistance genetic traits might reduce variation. Achieving
markers? ecosystem-level diversity often requires multiple
(A) Splicing management practices, not merely introducing a single
(B) Screening transgenic trait into cultivation systems.
(C) Hybridization
30. Assertion (A) : Bt toxin produced by Bacillus
(D) Electroporation
thuringiensis specifically targets certain insects without


Ans harming humans.
(B) Screening Reason (R) : Bt toxin crystallizes in alkaline insect
Screening employs selectable markers—often antibiotic midgut, but remains inactive in the acidic human
resistance genes—introduced into vectors alongside the stomach.
gene of interest. Only bacteria receiving the recombinant (A) Both (A) and (R) are true, and (R) is the correct
plasmid survive on antibiotic-containing media. This explanation of (A)
method reliably distinguishes transformed colonies (B) Both (A) and (R) are true, but (R) is NOT the
from non-transformants and ensures successful uptake correct explanation of (A)
of recombinant constructs for downstream applications (C) (A) is true, but (R) is false
in biotechnology. (D) (A) is false, but (R) is true

28. Which enzyme seals nicks in the sugar-phosphate

Ans

backbone of DNA fragments during recombinant DNA (A) Both (A) and (R) are true, and (R) is the correct
creation? explanation of (A)
(A) Helicase Bt toxin becomes active in the alkaline conditions of an
(B) Primase insect midgut, perforating the gut lining. Human gastric
(C) DNA ligase acidity keeps the protein denatured and harmless. Thus,
(D) Reverse transcriptase while Bt is lethal to certain insects, it is safe for humans,


Ans explaining its targeted pest-control role in agriculture.

(C) DNA ligase 31. Which approach best addresses concerns over GM crop
DNA ligase forms phosphodiester bonds between biosafety and public acceptance?
adjacent nucleotides, uniting the backbone of DNA (A) Rely solely on corporate claims of safety
strands. After restriction enzymes create complementary (B) Eliminate field trials entirely
sticky ends, ligase “glues” them together. This step (C) Conduct rigorous, transparent testing with
is crucial in forming stable recombinant molecules, regulatory oversight
enabling researchers to clone or manipulate genes for (D) Ban all biotech research indefinitely
further experimental or therapeutic uses.

Ans
29. Which of the following is NOT a correctly stated benefit (C) Conduct rigorous, transparent testing with
or feature of genetically modified (GM) crops? regulatory oversight
(A) Bt brinjal expressing cry genes to combat pests Balancing innovation and public welfare requires
(B) Increased nutritional content like Golden Rice for evidence-based risk assessments, open communication,
vitamin A and regulatory frameworks. Thorough testing
(C) Spontaneous biodiversity enrichment without identifies potential environmental or health risks,
external intervention while transparent data fosters public trust. Extreme
(D) Resistance to specific herbicides for weed measures like banning or halting trials impede scientific
management progress, whereas unverified corporate assurances risk


Ans undermining credibility and safety.

(C) Spontaneous biodiversity enrichment without 32. Analyze these statements on population attributes:
external intervention 1. Birth rate influences population size
GM crops can provide pest resistance, enhanced 2. Death rate is irrelevant to population growth
nutritional profiles, or tolerance to herbicides but do not 3. Age distribution affects reproductive potential

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 PRACTICE PAPER 06

4. Emigration and immigration can alter population curve encapsulates how resource constraints moderate
density real-world population expansion.
Which combination of statements is correct?
35. Which term describes the total biomass produced by
(A) 1, 3, and 4 only
(B) 2 and 4 only primary producers in a given area over a specific period,
(C) 1 and 2 only including what is later used in respiration?
(D) 1, 2, 3, and 4 (A) Primary productivity
(B) Gross primary productivity


Ans (C) Net primary productivity
(A) 1, 3, and 4 only (D) Secondary productivity
Birth and death rates both critically influence population

Ans
size, but statement 2 incorrectly downplays death
rate. Age distribution shapes reproductive capacity, (B) Gross primary productivity
while emigration and immigration modify population Gross primary productivity (GPP) refers to the total
density. These factors collectively drive population photosynthetic output by producers in an ecosystem. A
dynamics, dictating how populations expand, shrink, or portion of this is consumed in plant respiration, leaving
shift spatially over time. net primary productivity (NPP) as the energy available
to herbivores. GPP quantifies the ecosystem’s overall
33. Which type of interaction shows both species harmed photosynthetic capacity before subtracting respiratory
due to resource overlap, as commonly observed among costs.
similar organisms?
36. Match the following ecological terms in Column I with
(A) Commensalism
(B) Mutualism their descriptions in Column II:
(C) Predation Column I Column II
(D) Competition a. Detritivores i. Ratio of energy passed from


Ans one trophic level to another
(D) Competition b. Food chain ii. Sequence of who eats whom
Competition arises when organisms require the same c. Ecological iii. Total dry weight of living
limited resource, causing negative impacts for both efficiency organisms
sides. This struggle can lower growth or survival rates d. Biomass iv. Organisms that feed on
if resources are not plentiful. By contrast, mutualism dead organic matter
benefits both partners, commensalism benefits one
Options:
without harming the other, and predation benefits one
(A) a-iv, b-ii, c-i, d-iii
at the other’s expense.
(B) a-ii, b-iv, c-iii, d-i
34. In a logistic growth curve, which phase shows the (C) a-i, b-iii, c-ii, d-iv
population growing rapidly under favorable resource (D) a-iii, b-i, c-iv, d-ii
conditions, prior to reaching carrying capacity?

Ans
(A) Lag phase
(A) a-iv, b-ii, c-i, d-iii
(B) Exponential phase
Detritivores consume dead material, food chains
(C) Decline phase
describe feeding relationships, ecological efficiency
(D) Stationary phase
measures energy transfer between trophic levels,


Ans and biomass is the total dry mass of living entities.
(B) Exponential phase Understanding these concepts helps illustrate ecosystem
After a short lag phase, populations experience the structure, energy dynamics, and nutrient cycling across
exponential or log phase if resources are abundant, various habitats.
producing a steep rise in numbers. Eventually,
37. Arrange these stages in an aquatic ecosystem’s energy
environmental limitations slow growth, leading to a
flow in correct sequence:
stationary phase near carrying capacity. This S-shaped
1. Photosynthesis by phytoplankton
2. Consumption by zooplankton

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3. Decomposition of dead organisms pressures, driving the urgency for conservation

4. Predatory fish feeding on zooplankton measures to protect these unique organisms.
(A) 1→4→2→3
40. Examine these statements about factors leading to
(B) 1→2→4→3
(C) 2→1→3→4 biodiversity loss:
(D) 4→3→2→1 1. Habitat destruction
2. Overexploitation of resources


Ans 3. Invasive species introduction
(B) 1 → 2 → 4 → 3 4. Artificial selection enhancing genetic variation
Phytoplankton convert solar energy to biomass via Which combination of statements aggravate biodiversity
photosynthesis. Zooplankton feed on phytoplankton, loss?
then predatory fish consume zooplankton. Eventually, (A) 1, 2, and 3 only
organisms die and decomposers break down remains, (B) 2, 3, and 4 only
recycling nutrients. This sequence highlights how energy (C) 1 and 4 only
flows through trophic levels before returning materials (D) 1, 2, 3, and 4
to the system through decomposition processes.

Ans
38. Which conservation approach emphasizes the (A) 1, 2, and 3 only
protection of entire ecosystems in their natural habitats? Habitat destruction, overexploitation, and invasive
(A) Ex situ conservation in botanical gardens species heavily contribute to biodiversity decline.
(B) Gene banks preserving seeds for future use Artificial selection usually narrows genetic diversity in
(C) In situ conservation through protected areas domesticated species but doesn’t necessarily enhance it
(D) Intensive breeding programs in controlled facilities in wild populations. The listed anthropogenic pressures


Ans remain primary threats, underscoring the need for
sustainable practices and strict biosecurity measures.
(C) In situ conservation through protected areas
In situ conservation entails safeguarding species within

Direction :Carefully read the case study provided and then
their natural surroundings, allowing natural processes thoroughly answer the subsequent five questions.
and interactions to continue. Protected areas, such as Pranav, a senior biology student, conducted a field
wildlife sanctuaries and biosphere reserves, preserve study on pollinator-plant interactions in a local orchard.
ecological integrity and evolutionary processes. Ex He noticed that honeybees frequented bright, fragrant
situ strategies (seed banks or zoos) are supplementary, flowers, transferring pollen between them. However,
safeguarding genetic material outside original habitats. some plants had inconspicuous blooms relying on the
wind for pollination. Further observations revealed that
39. Assertion (A) : Endemic species found in biodiversity self-pollinating varieties often produced seeds even with
hotspots are at high risk of extinction. minimal pollinator activity. Intrigued, Pranav questioned
Reason (R) : These species typically have a wide the evolutionary advantages of cross-pollination
geographical distribution. versus self-pollination. He also discovered certain fruit
(A) Both (A) and (R) are true, and (R) is the correct growers were introducing managed bee colonies to boost
explanation of (A) yields. Yet concerns arose about pesticide use harming
(B) Both (A) and (R) are true, but (R) is NOT the pollinators. Pranav realized that while self-pollination
correct explanation of (A) ensures seed set, it limits genetic diversity compared
(C) (A) is true, but (R) is false to cross-pollination mediated by wind or insects. This
(D) (A) is false, but (R) is true balance between pollination modes directly influenced


Ans crop productivity and orchard sustainability.
(C) (A) is true, but (R) is false 41. Which primary advantage do plants gain from cross-
Endemic species occupy restricted ranges, heightening pollination as observed by Pranav?
their extinction risk under habitat destruction or climate (A) Ensures total uniformity in offspring
shifts. Contrary to the reason statement, their narrow (B) Improves genetic variation
distribution makes them more vulnerable. Hotspots (C) Removes all need for pollinators
have high endemism yet face intense anthropogenic (D) Guarantees seed production without fail

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 PRACTICE PAPER 06

Ans (A) They rely exclusively on water for pollen transfer

(B) Improves genetic variation (B) They produce seeds reliably but have limited
Cross-pollination involves pollen transfer between genetic diversity
different plants, introducing fresh allele combinations. (C) They yield faster-growing plants with higher fruit
Such genetic variation fosters adaptability, resilience to content
diseases, and evolutionary potential. Self-pollination, (D) They show absolutely no fertilization under any
though reliable, maintains stable traits but restricts pollination
diversity. The orchard’s reliance on managed bee colonies

Ans
highlights how external vectors can significantly
(B) They produce seeds reliably but have limited genetic
enhance cross-pollination outcomes.
diversity
42. Why were honeybees particularly effective pollinators Self-pollinating plants set seeds even when pollinator
in Pranav’s orchard? activity is low, ensuring reproductive success. However,
(A) They solely consume nectar from wind-pollinated this mode recycles existing alleles, constraining genetic
plants variation within the population. Cross-pollinating
(B) Their pollen baskets remove all pollen from flowers species accumulate more novel traits through gene
(C) They regularly visit numerous flowers, transferring exchange, potentially enhancing resilience and
pollen efficiently adaptability across changing environmental conditions.
(D) They avoid bright, fragrant blossoms
45. How did managed bee colonies affect the orchard’s fruit


Ans yields?
(C) They regularly visit numerous flowers, transferring (A) They replaced all natural pollinators completely
pollen efficiently (B) They caused pollinator crowding and flower
Honeybees gather nectar and pollen from multiple damage
blossoms, inadvertently transporting pollen among (C) They raised cross-pollination rates, improving fruit
them. Their body hairs and repeated foraging routes set
enhance pollination rates. By covering many flowers (D) They exclusively pollinated wind-pollinated crops
in a foraging trip, bees improve cross-pollination

Ans
opportunities, boosting fruit set. This mutualism
(C) They raised cross-pollination rates, improving fruit
benefits both pollinator nutritional needs and plant
set
reproduction.
Introducing managed honeybee colonies boosts the
43. What concern did Pranav identify regarding pesticide density of effective pollinators, enhancing cross-
use in the orchard? pollination efficiency for orchard plants. Higher cross-
(A) Pesticides have no effect on pollinators pollination often correlates with increased seed and
(B) Pesticides stimulate bee colony growth fruit production, benefiting overall yield. This strategic
(C) Pesticides can harm beneficial insects like addition of pollinators thus supports agricultural
honeybees productivity while highlighting the interplay between
(D) Pesticides make flowers more fragrant ecology and farming practices.


Ans

Direction :Carefully read the case study provided and then
(C) Pesticides can harm beneficial insects like honeybees thoroughly answer the subsequent five questions.
Pranav recognized that chemical pesticides, while Dr. Ahuja’s team worked on developing a fungal-based
targeting pests, may also negatively impact non- biocontrol agent to curb chemical pesticide usage. Field
target organisms, including pollinators vital for cross- trials involved releasing Trichoderma strains onto fields
pollination. Bee mortality or sublethal effects reduce prone to soil-borne fungal pathogens. Lab studies showed
pollination efficiency and threaten orchard yields. This that Trichoderma produced enzymes degrading the
highlights the need for integrated pest management that pathogen’s cell walls, while competing for nutrients. Crop
balances insect control with pollinator conservation. health improved as plant roots faced less disease pressure.
However, the team cautioned that widespread adoption
44. Which statement best summarizes Pranav’s observation required rigorous safety checks, ensuring no harmful
about self-pollinating varieties in the orchard? effects on beneficial organisms or soil ecology. Farmers

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appreciated reduced chemical inputs, yet regulatory (C) They needed evidence of minimal ecological harm
authorities demanded long-term data on environmental and pathogen resistance
persistence and possible resistance emergence in Regulators must ensure introduced biocontrol agents do
pathogens. Dr. Ahuja stressed that integrating biological not disrupt existing beneficial microbial communities
control with existing methods, such as crop rotation, or trigger resistant pathogenic strains. Long-term field
maintained sustainable pest management, balancing data can reveal unintended consequences, persistence
productivity and ecological harmony. in soil, and multi-season effects. This diligence
prevents ecological imbalances and fosters responsible
46. What primary role does Trichoderma play in Dr. Ahuja’s deployment of biologically based disease-management
biocontrol research? strategies.
(A) Promoting fungal pathogen growth
(B) Acting as a harmless soil fungus with no effect 49. How does Dr. Ahuja’s team suggest farmers integrate
(C) Producing enzymes that degrade harmful fungi Trichoderma to maintain sustainable pest management?
(D) Replacing fertilizers entirely (A) Apply Trichoderma alone and discard all other


Ans approaches
(B) Combine it with complementary methods like crop
(C) Producing enzymes that degrade harmful fungi rotation
Trichoderma releases enzymes like chitinases that (C) Use it exclusively for aerial pests
weaken or lyse pathogenic fungal cell walls. By limiting (D) Flood fields with the fungus immediately before
competitor fungi and outcompeting them for resources, harvest
it suppresses disease incidence in crops. Unlike chemical
agents, Trichoderma offers a biological means to control

Ans
pathogens, aligning with eco-friendly pest management (B) Combine it with complementary methods like crop
practices. rotation
Sustainable pest management relies on integrated
47. Which potential benefit motivated farmers to consider measures, reducing single-method dependence. Dr.
Trichoderma-based biocontrol, as stated in the case? Ahuja promotes synergy between biological control
(A) Complete elimination of all crop diseases forever (Trichoderma), cultural practices (crop rotation), and
(B) Lower chemical pesticide usage cautious chemical inputs. Such an approach maximizes
(C) Guaranteed yield doubling within one season disease suppression while minimizing resistance risks
(D) Immediate pest resistance to beneficial fungi and ecological harm, ensuring long-term agricultural


Ans productivity and environmental conservation.
(B) Lower chemical pesticide usage 50. What key principle underlies the adoption of biological
Farmers sought to reduce reliance on synthetic pesticides control agents in modern agriculture, as exemplified by
for cost savings, environmental protection, and food Dr. Ahuja’s project?
safety. Trichoderma-based agents suppress soil-borne (A) Eradicating all microflora in the soil
fungal pathogens naturally, mitigating chemical (B) Prioritizing short-term yields over ecosystem
residues. Although not a panacea, these biological balance
controls contribute to integrated pest management, (C) Harmonizing crop productivity with ecological
balancing productivity and ecosystem health over sustainability
traditional pesticide-dominated approaches. (D) Eliminating scientific regulation to speed
48. Why did regulatory authorities demand long-term data commercialization
before approving widespread adoption of Trichoderma?

Ans
(A) They required proof it lacks any beneficial qualities (C) Harmonizing crop productivity with ecological
(B) They insisted on total sterilization of soil microbes sustainability
(C) They needed evidence of minimal ecological harm Biological control agents aim to protect crops while
and pathogen resistance preserving beneficial organisms and soil health. By
(D) They wished to ban all biocontrol agents universally avoiding heavy pesticide use and leveraging naturally


Ans occurring antagonists like Trichoderma, farming
systems maintain biodiversity, reduce chemical inputs,

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 PRACTICE PAPER 06

and ensure long-term viability. This emphasizes the

eco-centric philosophy shaping sustainable agricultural
advances.

*************

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PRACTICE PAPER 07

1. Apomixis in flowering plants is best described as which tube growth if pollen and pistil share specific genetic
phenomenon? markers, thus promoting outbreeding and maintaining
(A) Formation of seeds involving gametic fusion genetic diversity in populations.
(B) Formation of seeds without gametic fusion
4. During human spermatogenesis, which pituitary
(C) Formation of zygote through pollination
(D) Formation of hybrid seeds artificially hormone directly stimulates Sertoli cells to facilitate
sperm maturation?


Ans (A) Luteinizing Hormone (LH)
(B) Formation of seeds without gametic fusion (B) Follicle-Stimulating Hormone (FSH)
Apomixis is a special reproductive process where seeds (C) Estrogen
develop in the absence of fertilization. No fusion of (D) Prolactin
male and female gametes occurs, causing offspring to

Ans
be genetically similar to the parent. This method can
preserve desired plant traits across generations without (B) Follicle-Stimulating Hormone (FSH)
the variability introduced by sexual reproduction. FSH acts on Sertoli cells found in the seminiferous
tubules. These cells provide nourishment and structural
2. Which floral structure specifically houses the support crucial for spermatogenesis. LH predominantly
microsporangia for pollen formation? stimulates Leydig cells to produce testosterone,
(A) Petals indirectly supporting sperm production, but the direct
(B) Anther lobes action on Sertoli cells is attributed to FSH.
(C) Stigma
5. Which function is NOT performed by the human
(D) Ovule integuments
placenta?


Ans (A) Exchange of gases
(B) Anther lobes (B) Transfer of nutrients
The anthers of a flower contain microsporangia, often (C) Removal of fetal waste
referred to as anther lobes, where microspore mother (D) Generation of sperm cells
cells undergo meiosis to form microspores. These

Ans
microspores mature into pollen grains, which serve as
the male gametophytes during the reproductive process (D) Generation of sperm cells
in flowering plants. The placenta facilitates nutrient and gas exchange
between maternal and fetal blood, along with waste
3. Which mechanism ensures cross-pollination by disposal. It also produces hormones supporting
preventing a flower’s own pollen from fertilizing its pregnancy. However, sperm cell production is exclusive
ovules? to the male testes and has no connection with placental
(A) Self-incompatibility function in the female body.
(B) Complete flower abscission
6. Compare embryo development in humans. Which is a
(C) External fertilization
(D) Apomixis common feature of early embryogenesis?
(A) Formation of a blastocyst prior to implantation


Ans (B) Direct fertilization in the uterine lining
(A) Self-incompatibility (C) Multiple uterus compartments to house separate
Self-incompatibility is a genetic mechanism wherein zygotes
pollen from the same plant cannot successfully fertilize (D) Oocyte division exclusively post-implantation
the ovules. It blocks pollen germination or pollen

Ans

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 PRACTICE PAPER 07

(A) Formation of a blastocyst prior to implantation embryos are transferred into the uterus. This approach
In human reproduction, after fertilization in the helps couples where blocked tubes prevent normal
fallopian tube, the zygote undergoes rapid cleavage fertilization.
to become a morula, then forms a blastocyst. This
10. Which statement best describes incomplete dominance
blastocyst implants into the uterine endometrium for
further development. The blastocyst stage is a hallmark in genetics?
of early mammalian embryogenesis. (A) A single dominant allele completely masks the
recessive
7. Which contraceptive method primarily prevents the (B) Both alleles remain unexpressed in the phenotype
secretion of FSH and LH by providing negative feedback (C) The heterozygote shows an intermediate trait
on the pituitary? (D) Two recessive alleles produce a codominant effect
(A) Condoms

Ans
(B) Intrauterine device (Copper-T)
(C) Oral contraceptive pills (C) The heterozygote shows an intermediate trait
(D) Spermicidal jellies In incomplete dominance, neither allele in a
heterozygote fully dominates. The resulting phenotype


Ans is intermediate compared to the parental forms. A
(C) Oral contraceptive pills classic example is crossing red and white snapdragons to
Oral contraceptive pills typically contain synthetic produce pink flowers, demonstrating partial expression
estrogen and/or progesterone. These hormones exert from both alleles.
negative feedback on the anterior pituitary, reducing
11. Codominance differs from incomplete dominance in
FSH and LH levels. This inhibition prevents the ovarian
follicle from maturing and halts ovulation, thereby that codominance:
averting pregnancy. (A) Involves complete suppression of one allele
(B) Expresses both alleles distinctly without blending
8. Amniocentesis is used to identify: (C) Causes complete blending of phenotypes
(A) Placental malfunction only (D) Occurs only in recessive genetic disorders
(B) Hormonal imbalances in the mother

Ans
(C) Chromosomal abnormalities in the fetus
(D) Testosterone levels in fetal circulation (B) Expresses both alleles distinctly without blending
Codominance lets each allele in a heterozygote manifest


Ans equally and visibly in the phenotype, like AB blood type
(C) Chromosomal abnormalities in the fetus where both IA and IB alleles are expressed. In contrast,
Amniocentesis involves extracting a sample of amniotic incomplete dominance yields a blended intermediate
fluid containing fetal cells. Genetic and chromosomal phenotype.
analyses can detect abnormalities such as Down’s
12. Which human blood group is known as the universal
syndrome or other inherited disorders. This prenatal
diagnostic procedure helps expectant parents make recipient?
informed decisions on managing high-risk pregnancies. (A) Blood group A
(B) Blood group B
9. When a woman’s fallopian tubes are blocked yet her (C) Blood group AB
ovaries produce viable ova, the best infertility treatment (D) Blood group O
option is:

Ans
(A) Tubal ligation
(B) In vitro fertilization (IVF) (C) Blood group AB
(C) Coitus interruptus Individuals with blood group AB possess both A and
(D) Condom usage B antigens on their RBCs but lack anti-A and anti-B
antibodies. Thus, they can receive blood from all groups


Ans without immunological complications, earning them
(B) In vitro fertilization (IVF) the title “universal recipient.”
IVF bypasses obstructed fallopian tubes by allowing
13. Assertion (A) : The chromosomal theory of inheritance
fertilization outside the body. Retrieved ova and
sperm combine in a laboratory setting, and resulting correlates gene behavior with chromosome movement.

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page 70 CUET UG Biology

Reason (R) : Genes on the same chromosome strictly

Ans

segregate independently. (D) Removing exons from the final transcript
(A) Both Assertion and Reason are true, and Reason is Eukaryotic pre-mRNA undergoes capping at the 5’
the correct explanation end, intron removal (splicing), and 3’ polyadenylation
(B) Both Assertion and Reason are true, but Reason is (adding a poly-A tail). Exons, which encode the final
not the correct explanation protein, remain. Removing exons would eliminate
(C) Assertion is true but Reason is false coding segments, contradicting normal mRNA
(D) Both Assertion and Reason are false processing.


Ans
17. In prokaryotic DNA replication, arrange the following
(C) Assertion is true but Reason is false steps in sequence:
The chromosomal theory indicates that genes are 1. Helicase unwinds DNA
located on chromosomes and segregate during gamete 2. Primase lays down RNA primer
formation. However, genes on the same chromosome 3. DNA polymerase III elongates new strands
can be linked and inherited together unless crossing 4. DNA ligase seals gaps
over separates them, disproving the idea of strict (A) 1 → 2 → 3 → 4
independent segregation. (B) 2 → 1 → 3 → 4
(C) 1 → 3 → 2 → 4
14. Which team demonstrated that DNA is the
(D) 2 → 3 → 1 → 4
“transforming principle” in bacteria?
(A) Hershey and Chase

Ans
(B) Avery, MacLeod, and McCarty (A) 1 → 2 → 3 → 4
(C) Watson and Crick Replication begins with helicase unwinding the double
(D) Meselson and Stahl helix, followed by primer synthesis, which provides


Ans a free 3’ end for DNA polymerase III to extend. DNA
ligase closes any nicks, ensuring a continuous new
(B) Avery, MacLeod, and McCarty
strand.
Avery, MacLeod, and McCarty expanded on Griffith’s
experiments and showed that DNA, not protein, 18. Which is NOT considered evidence supporting organic
was responsible for transformation in bacteria. Their evolution?
findings established DNA as the primary carrier of (A) Fossils
genetic information. (B) Vestigial organs
(C) Analogous structures
15. The “Central Dogma” of molecular biology states:
(D) Supernatural creation events
(A) DNA → RNA → Protein
(B) Protein → DNA → RNA

Ans
(C) RNA → DNA → Protein (D) Supernatural creation events
(D) DNA → Protein → RNA Fossil records, vestigial organs, and analogous structures


Ans are scientifically recognized lines of evidence showing
evolutionary relationships. Direct creation concepts lie
(A) DNA → RNA → Protein
outside the purview of evidence-based evolutionary
Francis Crick’s Central Dogma posits a unidirectional
theory, which relies on gradual processes of natural
flow of genetic information: DNA is transcribed into
change over geological timescales.
RNA, which is then translated into proteins. This
framework underscores fundamental gene expression 19. Arrange these major evolutionary milestones in the
processes in most organisms. correct chronological order:
1. Protobionts
16. Which event does NOT occur during eukaryotic mRNA
2. Prokaryotic cells
processing?
3. Eukaryotic cells
(A) Addition of a 5’ cap
4. Multicellularity
(B) Splicing out of introns
(A) 1 → 2 → 3 → 4
(C) Adding a poly-A tail
(B) 2 → 1 → 3 → 4
(D) Removing exons from the final transcript

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(C) 1 → 3 → 2 → 4 Metastasis involves cancerous cells detaching from a

(D) 3 → 2 → 4 → 1 primary tumor, moving through the bloodstream or


Ans lymphatic system, and establishing secondary tumors
in other organs. This capacity for uncontrolled spread
(A) 1 → 2 → 3 → 4 distinguishes malignant tumors from benign ones.
The hypothesized timeline proposes that protobionts
arose first, leading to prokaryotes, followed by the 23. Which of the following does NOT help prevent HIV
evolution of more complex eukaryotes, and finally the transmission?
emergence of multicellular organisms. Each step reflects (A) Safe blood transfusion practices
an increase in structural and functional complexity. (B) Consistent use of condoms
(C) Sterile needle use
20. Assertion (A) : Natural selection acts on existing (D) Sharing contaminated syringes
variations in a population.
Reason (R) : Natural selection eliminates all genetic

Ans
diversity immediately. (D) Sharing contaminated syringes
(A) Both Assertion and Reason are true, and Reason is HIV is transmissible via infected bodily fluids, including
the correct explanation blood. Avoiding shared or unsterilized syringes is
(B) Both Assertion and Reason are true, but Reason is vital for prevention. Safe sex, screened blood, and
not the correct explanation sterile injections all reduce HIV spread, whereas using
(C) Assertion is true but Reason is false contaminated needles perpetuates transmission.
(D) Both Assertion and Reason are false
24. In sewage treatment, how do microbes function to make


Ans wastewater safer?
(C) Assertion is true but Reason is false (A) They release toxins to neutralize pollutants
Natural selection favors variations advantageous under (B) They convert heavy metals into organic waste
specific environmental conditions but does not eradicate (C) They decompose and break down organic matter
all diversity. Neutral or less disadvantageous variants (D) They form unsightly foams that trap contaminants
may persist, maintaining genetic variability across

Ans
generations. Hence, while selection requires variation,
it does not instantly remove all diversity. (C) They decompose and break down organic matter
Microbes in sewage treatment plants metabolize
21. Which mosquito species transmits dengue fever? complex organic materials, reducing biological oxygen
(A) Anopheles demand and improving water quality. Through
(B) Aedes aerobic or anaerobic processes, they transform waste
(C) Culex into simpler, less harmful substances, enabling safer
(D) Mansonia discharge.


Ans 25. “Biocontrol” means controlling pests using:
(B) Aedes (A) Genetically modified seeds
Dengue fever is primarily spread by Aedes aegypti (B) Chemical pesticides
mosquitoes. They breed in stagnant water, bite during (C) Natural predators or pathogens
the daytime, and transmit the dengue virus. Eliminating (D) Ionizing radiation
breeding sites and using protective measures like nets

Ans
and repellents can reduce infection risk.
(C) Natural predators or pathogens
22. In cancer terminology, “metastasis” refers to: Biocontrol harnesses an ecosystem’s own checks and
(A) Benign tumor growth balances, using organisms like ladybugs or bacterial
(B) Controlled cell division pathogens to keep pests in check. This reduces reliance
(C) Spread of cancer cells to distant tissues on synthetic chemical pesticides, fostering a more
(D) Maintenance of normal tissue architecture sustainable approach to pest management.


Ans 26. Which microorganism is most widely used for
(C) Spread of cancer cells to distant tissues commercial ethanol production?

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(A) Lactobacillus acidophilus 29. In genetic engineering, plasmids serve primarily as:
(B) Saccharomyces cerevisiae (A) Enzymes to digest foreign DNA
(C) Penicillium notatum (B) Replication inhibitors
(D) Rhizobium leguminosarum (C) Vectors to carry genes into host cells


Ans (D) Proteins that regulate gene expression

(B) Saccharomyces cerevisiae

Ans

Saccharomyces cerevisiae (baker’s yeast) ferments (C) Vectors to carry genes into host cells
sugars to produce ethanol and carbon dioxide. It is Plasmids are small, self-replicating DNA molecules used
indispensable in brewing, winemaking, and biofuel as cloning vectors. Scientists insert target genes into
industries due to its efficient fermentation properties plasmids and introduce them into host organisms for
and relatively simple cultivation requirements. replication and often expression of the inserted genes.

27. Which enzyme is crucial for cutting DNA at specific 30. Bt cotton contains a Bacillus thuringiensis gene that:
sequences to form recombinant DNA? (A) Promotes drought tolerance
(A) RNA polymerase (B) Enhances fiber length
(B) DNA polymerase (C) Confers insect resistance
(C) Restriction endonuclease (D) Increases flower size
(D) Reverse transcriptase

Ans


Ans (C) Confers insect resistance
(C) Restriction endonuclease Bt cotton plants express a Cry protein that is toxic to
Restriction endonucleases recognize short, often specific pests (notably bollworms). When the insect
palindromic, nucleotide sequences and cleave DNA at or ingests the protein, it disrupts the pest’s gut lining.
near those sites. This precise cleavage creates fragments This transgenic approach reduces reliance on chemical
that can be joined (ligated) to form recombinant DNA insecticides.
molecules in genetic engineering.
31. What is the main advantage of gene therapy?
28. Match the following (A) It blocks all protein synthesis
(B) It delivers functional genes to correct genetic
Column I (Step) Column II (Description)
defects
a. Ligation i. Amplifying DNA fragments (C) It promotes random mutations for variation
by repeated cycles (D) It permanently halts cell division
b. Isolation ii. Joining of cut DNA fragments


Ans
c. PCR iii. Cutting DNA at specific
restriction sites (B) It delivers functional genes to correct genetic defects
Gene therapy introduces functional genes to replace
d. Restriction iv. Separating and extracting
or supplement faulty ones, targeting the root cause of
DNA from the cell matrix
certain genetic conditions. This differs from traditional
Options: treatments that often focus on managing symptoms
(A) a-ii, b-iv, c-i, d-iii rather than correcting the underlying defect.
(B) a-iv, b-ii, c-iii, d-i
(C) a-iii, b-i, c-iv, d-ii 32. Assertion (A) : Transgenic animals can be engineered to
(D) a-i, b-iii, c-iv, d-ii produce valuable proteins.
Reason (R) : Introducing foreign genes into an animal


Ans
immediately halts its natural physiological processes.
(A) a-ii, b-iv, c-i, d-iii (A) Both Assertion and Reason are true, and Reason is
Ligation (ii) joins DNA fragments, isolation (iv) the correct explanation
separates DNA from cell material, PCR (i) amplifies (B) Both Assertion and Reason are true, but Reason is
DNA, and restriction (iii) uses enzymes to cut DNA. not the correct explanation
Understanding these steps is essential for constructing (C) Assertion is true but Reason is false
recombinant molecules. (D) Both Assertion and Reason are false

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Ans (C) a-iv, b-ii, c-i, d-iii

(C) Assertion is true but Reason is false (D) a-i, b-iii, c-ii, d-iv
Transgenic animals, like those expressing therapeutic

Ans
proteins in their milk, help in producing high-value
(A) a-ii, b-iv, c-iii, d-i
biopharmaceuticals. However, gene insertion typically
Birth rate = new individuals per time, death rate =
complements normal physiology rather than stopping
individuals dying, immigration = incoming individuals,
it. Proper regulation ensures that natural processes
and emigration = departing individuals. These four
continue alongside production of the foreign protein.
parameters combine to influence population size and
33. How does predation differ from parasitism? demographics.
(A) Predation typically kills the prey quickly
36. “Primary productivity” in an ecosystem is:
(B) Parasitism kills the host immediately
(A) Decomposition of organic materials
(C) Both always involve swift organism death
(B) Conversion of carbon dioxide into glucose by
(D) Predators never consume the prey’s tissue
producers


Ans (C) The combined biomass of all herbivores
(A) Predation typically kills the prey quickly (D) Energy lost at each trophic level
Predators hunt and kill their prey for food. In parasitism,

Ans
the parasite depends on the host but usually does not kill
(B) Conversion of carbon dioxide into glucose by
it promptly, as prolonged host viability benefits parasite
producers
survival. This fundamental difference separates the two
Primary productivity denotes the rate at which
interactions.
photosynthetic organisms capture and store energy
34. A rapidly growing human population often shows which through photosynthesis, usually measured as biomass
age pyramid characteristic? accumulation per unit time. This is the foundational
(A) Narrow base, broad apex energy input for higher trophic levels.
(B) Broad base, narrow apex
37. Compare the pyramid of energy to the pyramid of
(C) Uniform shape across all ages
biomass. Which is always true for the pyramid of
(D) Inverted structure with no younger individuals
energy?


Ans (A) It can sometimes be inverted in aquatic systems
(B) Broad base, narrow apex (B) It always narrows at higher trophic levels due to
Rapidly expanding populations have more young energy loss
individuals than old. This distribution forms a wide (C) It shows the same shape as the biomass pyramid
base (representing children) and a narrower top (fewer (D) It measures the number of organisms at each level
elderly), depicting higher birth rates.

Ans
35. Match the following population parameters with their (B) It always narrows at higher trophic levels due to
definitions: energy loss
Energy pyramids cannot be inverted because each
Column I Column II higher level receives only a fraction of the energy from
a. Birth rate
i. Number leaving the the level below. Biomass pyramids can invert (especially
population in aquatic systems), but energy flow is strictly reduced at
b. Death rate ii. New individuals added per each trophic stage.
unit time
38. Which factor does NOT typically drive biodiversity
c. Immigration iii. Individuals arriving from
loss?
outside
(A) Habitat destruction
d. Emigration iv. Individuals dying per unit (B) Overexploitation of species
time (C) Climate stability
Options: (D) Invasive species introduction
(A) a-ii, b-iv, c-iii, d-i

Ans
(B) a-iii, b-ii, c-iv, d-i

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(C) Climate stability she married a male with the mutated allele. She wondered
Biodiversity declines frequently stem from habitat about probability of transmission across generations.
destruction, overexploitation, invasive species, and
41. Haemophilia generally follows which inheritance
rapid climate changes. Stable environmental conditions
generally support existing biodiversity, whereas abrupt pattern?
climate shifts can exacerbate species loss. (A) Autosomal dominant
(B) Autosomal recessive
39. Which of the following is NOT a conservation method (C) X-linked recessive
for biodiversity? (D) Y-linked recessive
(A) Establishing biosphere reserves

Ans
(B) Encouraging poaching
(C) Maintaining botanical gardens (C) X-linked recessive
(D) Preserving sacred groves Haemophilia typically manifests as an X-linked recessive
disorder. Males inherit the affected X chromosome and


Ans become symptomatic, while most females carrying one
(B) Encouraging poaching mutated X remain asymptomatic carriers. This pattern
Conservation aims to protect species and their explains why the condition is far more common in
habitats. Poaching, or illegal hunting, damages wildlife males.
populations and runs contrary to all conservation
42. If Neha’s father shows no haemophilia symptoms, what
efforts. Botanical gardens, sacred groves, and biosphere
reserves help maintain genetic diversity and ecosystems. does that imply about his X chromosome regarding the
disorder?
40. Which region is recognized as a biodiversity hotspot in (A) He must carry a silent mutation
India? (B) He passes the defective allele to all sons
(A) Aravalli Hills (C) He lacks the mutated allele for haemophilia
(B) Chambal Basin (D) He can transmit it to daughters with 100% certainty
(C) Western Ghats

Ans
(D) Deccan Plateau
(C) He lacks the mutated allele for haemophilia


Ans Fathers pass their Y chromosome to sons and their X
(C) Western Ghats chromosome to daughters. An unaffected father has
India’s Western Ghats is a globally recognized a normal X chromosome without the haemophilia
biodiversity hotspot. It hosts high species endemism and mutation, so he cannot pass that defective allele to any
is threatened by habitat fragmentation. Conservation offspring.
efforts are crucial to protect the region’s unique flora
43. Which reasoning explains Neha’s 50% chance of carrier
and fauna.
status?


Direction :Carefully read the case study provided and then (A) Both her parents must have two defective alleles
thoroughly answer the subsequent five questions. (B) Only paternal inheritance matters
Neha, a Class 12 student, noticed that her family has a (C) Her mother has one defective X and one normal X
history of a certain recessive genetic disorder affecting (D) Father’s Y chromosome always leads to carriers
blood clotting. Intrigued, she delved into her own

Ans
genetic testing. Her mother is a carrier, while her father
is unaffected. To understand the pattern of inheritance, (C) Her mother has one defective X and one normal X
she studied concepts of sex-linked traits, particularly A carrier mother (heterozygous) has a 50% probability
haemophilia. She learned that the gene for this disorder of transmitting her mutated X chromosome to each
is located on the X chromosome and that males are daughter. Since the father’s X chromosome is normal,
more frequently affected than females. Though her daughters receiving the mutated maternal X will
father did not exhibit symptoms, Neha discovered a 50% become carriers, while those receiving the normal X will
chance of inheriting the carrier status from her mother. be unaffected.
This realization emphasized the importance of genetic 44. Which statements about haemophilia are true?
counseling, as her future offspring could also face the risk if 1. It is X-linked recessive

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2. Carriers often show mild or no symptoms release of genetically modified organisms. Seeing the
3. Fathers always pass the condition to their sons positive impact on numerous patients worldwide, Raj
4. One mutant allele can make a male haemophiliac realized how biotechnology solutions can address pressing
(A) 1, 2, and 3 medical challenges and enhance global healthcare. This
(B) 1, 2, and 4 innovation exemplifies collaboration between science and
(C) 2, 3, and 4 industry.
(D) 1, 3, and 4
46. What primary advantage does recombinant human


Ans insulin hold over animal insulin?
(B) 1, 2, and 4 (A) It elicits stronger immune responses
Haemophilia is X-linked recessive (1). Female carriers (B) It is incompatible with human physiology
typically have mild or no symptoms (2). Males possessing (C) It reduces allergic reactions
a single defective allele on their X chromosome manifest (D) It can only be administered orally
the disorder (4). Fathers do not transmit the mutant X

Ans
to sons, making statement 3 incorrect.
(C) It reduces allergic reactions
45. Assertion (A) : Genetic counseling helps families Recombinant human insulin closely mimics naturally
understand and manage inherited disorders like produced human insulin, minimizing the immune
haemophilia. responses often seen with animal-derived insulin. This
Reason (R) : Genetic counseling completely eliminates increases patient safety and comfort by reducing the risk
the risk of genetic conditions. of hypersensitivity and other side effects.
(A) Both Assertion and Reason are true, and Reason is
47. How do bacteria typically acquire the human insulin
the correct explanation
(B) Both Assertion and Reason are true, but Reason is gene in recombinant technology?
not the correct explanation (A) By random environmental mutations
(C) Assertion is true but Reason is false (B) Through specialized plasmid vectors
(D) Both Assertion and Reason are false (C) Via direct injection into their cytoplasm
(D) By spontaneously producing the insulin gene


Ans


Ans
(C) Assertion is true but Reason is false
Genetic counseling offers insights into inheritance (B) Through specialized plasmid vectors
patterns, carrier risks, and diagnostic procedures. Researchers clone the insulin gene into a plasmid, which
However, it does not guarantee the prevention or is then introduced into bacterial cells. These plasmids
elimination of genetic diseases. Counseling informs self-replicate and express the inserted gene, enabling
decision-making but cannot eradicate the genetic bacteria to produce human insulin in large quantities
mutation itself. under appropriate conditions.

48. Why are large bioreactors used for transgenic bacterial

Direction :Carefully read the case study provided and then
thoroughly answer the subsequent five questions. cultures?
Raj, a biotechnology undergraduate, became fascinated (A) To increase random mutations
with genetically engineered bacteria after learning about (B) To ensure optimal, controlled growth conditions
recombinant human insulin production. He explored how for maximum yield
scientists insert the human insulin gene into a bacterial (C) To restrict oxygen supply
plasmid, enabling the microbes to produce insulin (D) To eliminate the need for sterile techniques
identical to the human hormone. He noted that this

Ans
recombinant DNA technology bypasses reliance on animal (B) To ensure optimal, controlled growth conditions for
insulin, minimizing immunological reactions in diabetic maximum yield
patients. Visiting a pharmaceutical facility, Raj observed Bioreactors provide meticulously regulated
large bioreactors cultivating transgenic bacteria under environments (temperature, pH, aeration), promoting
controlled conditions, ensuring proper protein folding and robust bacterial growth and protein expression. This
efficacy of the insulin produced. He also discovered the controlled scaling is essential for producing commercial
stringent safety protocols in place to prevent accidental

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volumes of therapeutic proteins like insulin with

consistent quality.

49. Match the steps in recombinant insulin production with

their descriptions:
Column I Column II
a. Isolation of gene i.
Growing transformed
cells in large fermenters
b. Insertion into ii. Cutting DNA to obtain
plasmid insulin gene
c. Transformation iii. Introducing recombinant
DNA into host bacteria
d. Large-scale iv. Ligation of the gene into
culture a circular DNA vector
Options:
(A) a-iii, b-i, c-iv, d-ii
(B) a-ii, b-iv, c-iii, d-i
(C) a-iv, b-ii, c-i, d-iii
(D) a-i, b-iii, c-ii, d-iv


Ans
(B) a-ii, b-iv, c-iii, d-i
First, scientists isolate the insulin gene by cutting DNA
(ii). This gene is inserted into the plasmid via ligation
(iv). The recombinant plasmid is transformed into
bacterial cells (iii). Finally, large-scale culture (i) in
fermenters yields mass insulin production.

50. Assertion (A) : Strict safety measures are crucial in

recombinant DNA laboratories.
Reason (R) : Genetically modified microbes are
invariably more virulent than wild strains.
(A) Both Assertion and Reason are true, and Reason is
the correct explanation
(B) Both Assertion and Reason are true, but Reason is
not the correct explanation
(C) Assertion is true but Reason is false
(D) Both Assertion and Reason are false


Ans
(C) Assertion is true but Reason is false
Safeguards prevent accidental release of GMOs and
protect personnel. Yet genetic modifications for insulin
production do not inherently increase microbial
virulence. Many transgenic bacteria remain harmless
except for the introduced beneficial trait.

*************

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PRACTICE PAPER 08

1. The phenomenon by which two male gametes are 4. Which of the following is NOT a role of the epididymis
released into the embryo sac via the pollen tube is called: in males?
(A) Single fertilization (A) Storage of sperm
(B) Double fertilization (B) Maturation of sperm
(C) Pseudo-fertilization (C) Secretion of seminal fluid components
(D) Triple fusion only (D) Passage of sperm to the vas deferens


Ans

Ans
(B) Double fertilization (C) Secretion of seminal fluid components
In angiosperms, the pollen tube delivers two male The epididymis stores and matures sperm. Seminal fluid
gametes. One fertilizes the egg to form a zygote, while components mainly originate from the seminal vesicles,
the other fuses with polar nuclei to create triploid prostate gland, and bulbourethral glands, not from the
endosperm. This distinctive double fertilization epididymis. After final maturation, sperm travel via the
maximizes efficiency in resource allocation for seed vas deferens to be mixed with accessory gland fluids.
development.
5. Assertion (A) : Menstrual cycle regulation involves
2. Which trait helps certain flowers avert self-pollination? hormones from both pituitary and ovaries.
(A) Bisexual floral structure Reason (R) : An LH surge causes a drastic reduction in
(B) Self-incompatibility systems estrogen levels.
(C) Nectar production for insects (A) Both Assertion and Reason are true, and Reason is
(D) Large colorful petals the correct explanation


Ans (B) Both Assertion and Reason are true, but Reason is
not the correct explanation
(B) Self-incompatibility systems (C) Assertion is true but Reason is false
A self-incompatibility mechanism genetically blocks a (D) Both Assertion and Reason are false
plant’s own pollen from effectively fertilizing its ovules.
This promotes cross-pollination by requiring pollen

Ans
from genetically different individuals, thus enhancing (C) Assertion is true but Reason is false
genetic diversity. The menstrual cycle is governed by FSH, LH from the
pituitary, and estrogen, progesterone from the ovaries.
3. In flowering plants, polyembryony results in: LH surge triggers ovulation and helps form the corpus
(A) Multiple embryos in a single seed luteum, not a sudden drop in estrogen. Therefore, the
(B) Two seeds merging into one stated reason is incorrect.
(C) Sterile seeds lacking embryos
(D) Multiple pollen tubes in one ovary 6. “Colostrum” is described as:


Ans (A) The primary hormone for ovulation
(B) Thick, antibody-rich milk first produced
(A) Multiple embryos in a single seed postpartum
Polyembryony occurs when multiple embryos form (C) Synovial fluid around joints
within the same seed, often through cleavage of the (D) Gastric juice secreted during digestion
zygote or development of additional embryos from
nucellar cells. This can produce more than one seedling

Ans
from a single fertilized ovule. (B) Thick, antibody-rich milk first produced postpartum
Colostrum is a nutrient-dense, immune-boosting
fluid secreted initially by mammary glands. Packed

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with proteins, vitamins, and antibodies, it provides 10. Match the following genetic terms with their
newborns with essential immunological protection and descriptions:
nourishment.
Column I Column II
7. Which practice most effectively reduces the risk of STIs? a. Pleiotropy i. Several genes influence a
(A) Sole reliance on withdrawal method single trait
(B) Routinely using barrier protection during b. Multiple allelism ii. Alleles are equally
intercourse expressed in phenotype
(C) Monthly antibiotic consumption regardless of c. Polygenic iii. One gene affects multiple
infection inheritance traits
(D) Using no contraception for “natural” contact
d. Codominance iv. More than two alleles for


Ans a given gene
(B) Routinely using barrier protection during Options:
intercourse (A) a-iii, b-iv, c-i, d-ii
Barrier methods, such as condoms, physically block (B) a-i, b-ii, c-iv, d-iii
exchange of sexual fluids, which can harbor STI (C) a-iv, b-iii, c-ii, d-i
pathogens. Regular and correct use provides proven (D) a-ii, b-i, c-iii, d-iv
protection against various infections, whereas


Ans
withdrawal or random antibiotics are neither reliable
nor recommended prophylactic measures. (A) a-iii, b-iv, c-i, d-ii
Pleiotropy involves a single gene influencing multiple
8. Compare Medical Termination of Pregnancy (MTP) traits, multiple allelism means more than two alleles exist
and contraceptive methods. A key distinction is that for a gene, polygenic inheritance entails multiple genes
MTP: controlling a single trait, and codominance describes
(A) Prevents fertilization both alleles being distinctly expressed in a heterozygote.
(B) Occurs pre-fertilization
(C) Terminates an established pregnancy 11. Which of the following is NOT an X-linked disorder?
(D) Promotes gamete formation (A) Haemophilia
(B) Colour blindness


Ans
(C) Thalassemia
(C) Terminates an established pregnancy (D) Duchenne muscular dystrophy
Contraceptives work to avoid pregnancy by preventing


Ans
fertilization or implantation. MTP (abortion) is a
medical procedure to end a pregnancy after fertilization. (C) Thalassemia
This post-conception intervention contrasts with pre- Thalassemias commonly arise from autosomal gene
fertilization contraceptive techniques. defects affecting hemoglobin synthesis, typically on
chromosomes 11 or 16. Haemophilia, colour blindness,
9. Zygote Intra Fallopian Transfer (ZIFT) involves: and Duchenne muscular dystrophy are frequently
(A) Transferring the blastocyst into the uterus associated with mutations on the X chromosome.
(B) Introducing gametes into the fallopian tube
(C) Placing a fertilized egg at the 2-celled stage into the 12. Meselson and Stahl’s experiments demonstrated that
fallopian tube DNA replication is:
(D) Artificially inseminating sperm directly into the (A) Conservative
uterus (B) Semiconservative
(C) Dispersive


Ans
(D) Random
(C) Placing a fertilized egg at the 2-celled stage into the


Ans
fallopian tube
In ZIFT, fertilization occurs outside the body, and the (B) Semiconservative
zygote (often at the 2-celled cleavage stage) is then Using E. coli grown in heavy and light nitrogen isotopes,
transferred into the fallopian tube. This differs from Meselson and Stahl showed that after replication each
IVF-ET, where the embryo is placed into the uterus. daughter DNA molecule contains one old (parental)

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 PRACTICE PAPER 08

strand and one newly synthesized strand, confirming Soot-darkened environments favored darker moths,
semiconservative replication. shifting population coloration. This is a textbook
example of directional selection, where one phenotype
13. In the lac operon, the gene “i” codes for: is consistently favored, altering allele frequencies toward
(A) The structural enzyme β-galactosidase that characteristic.
(B) The repressor protein
(C) The promoter region 17. Place these early-life formation events in chronological
(D) Lactose sequence:


Ans 1. Simple organic molecules
2. Complex polymers
(B) The repressor protein 3. Protobionts
The lac i gene produces the repressor protein that binds 4. Genetic material
to the operator in the absence of lactose, blocking (A) 1 → 3 → 2 → 4
transcription of the structural genes. Lactose or its (B) 1 → 2 → 3 → 4
isomer allolactose inactivates the repressor, enabling (C) 2 → 1 → 4 → 3
gene expression. (D) 3 → 1 → 2 → 4
14. The promoter region of a prokaryotic gene primarily:

Ans
(A) Codes for a repressor protein (B) 1 → 2 → 3 → 4
(B) Is responsible for intron splicing Early Earth conditions first formed simple organics,
(C) Provides a binding site for RNA polymerase which polymerized into more complex molecules.
(D) Translates mRNA to protein Protobionts (primitive membrane-bound structures)


Ans subsequently emerged. Genetic material (likely RNA
(C) Provides a binding site for RNA polymerase initially) arose to facilitate hereditary mechanisms,
In prokaryotes, the promoter lies upstream of coding refining protobiont complexity into proto-cells.
sequences, featuring specific consensus sites for RNA 18. Which disease is NOT viral in origin?
polymerase attachment. Once bound, the polymerase (A) Chikungunya
initiates mRNA synthesis, driving gene expression. (B) Dengue
15. How does genetic drift differ from natural selection? (C) Typhoid
(A) Genetic drift always favors beneficial traits (D) Common cold
(B) Genetic drift is a random change in allele

Ans
frequencies (C) Typhoid
(C) Natural selection is purely random Typhoid is caused by Salmonella Typhi, a bacterial
(D) Genetic drift cannot influence small populations pathogen. Dengue, chikungunya, and the common


Ans cold each have viral etiologies. Identifying pathogens is
(B) Genetic drift is a random change in allele frequencies crucial for choosing correct treatments and preventive
Unlike natural selection, which systematically favors measures.
adaptations beneficial for survival, genetic drift operates 19. Vaccines are generally:
by chance, especially in small populations. Beneficial, (A) High-dose antibiotics for pathogen elimination
neutral, or slightly harmful alleles can become prevalent (B) Weakened or inactivated pathogens that stimulate
due to random sampling events. immunity
16. Industrial melanism seen in peppered moths exemplifies: (C) Substances that cause autoimmunity
(A) Stabilizing selection (D) Hormones that speed tissue repair
(B) Disruptive selection

Ans
(C) Directional selection (B) Weakened or inactivated pathogens that stimulate
(D) Genetic drift immunity


Ans Vaccines contain antigenic components (often weakened
(C) Directional selection or killed forms) that do not typically cause severe
disease but prime the immune system to recognize and

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page 80 CUET UG Biology

mount a strong defense upon future exposure to the live 23. Arrange these sewage treatment stages in order:
pathogen. 1. Primary sedimentation
2. Sludge digestion
20. Which statements about HIV infection are correct? 3. Screening
1. It targets helper T-cells 4. Secondary aeration
2. It spreads via infected blood (A) 1 → 3 → 4 → 2
3. It is primarily a bacterial infection (B) 3 → 1 → 4 → 2
4. Antiretroviral drugs can suppress viral load (C) 2 → 1 → 3 → 4
(A) 1, 2, and 3 (D) 1 → 4 → 3 → 2
(B) 2, 3, and 4
(C) 1, 2, and 4

Ans
(D) 1, 3, and 4 (B) 3 → 1 → 4 → 2


Ans First, large debris is removed by screening (3). Then,
primary sedimentation (1) settles suspended solids.
(C) 1, 2, and 4 Secondary aeration (4) uses microbes to decompose
HIV infects and destroys helper T-cells (1), can be organic matter. Lastly, sludge digestion (2) degrades
transmitted through blood or other bodily fluids leftover solids, producing biogas and reducing
(2), and is a retrovirus, not a bacterium (3 is false). pathogens.
Antiretroviral therapy helps reduce viral replication and
improve patient outcomes (4). 24. Match each PCR component with its primary role:

21. Which microbe is known for generating the large holes Column I Column II
in Swiss cheese? a. Taq DNA i.Short DNA strands
(A) Streptococcus thermophilus polymerase marking amplification
(B) Penicillium roqueforti targets
(C) Propionibacterium shermanii b. Primers ii. Deoxynucleotide building
(D) Saccharomyces cerevisiae blocks


Ans c. Thermal cycler iii. Controls denaturation and
(C) Propionibacterium shermanii annealing cycles
Propionibacterium shermanii ferments lactic acid to d. dNTPs iv. Synthesizes new DNA
produce carbon dioxide gas, forming the characteristic strands
holes in Swiss cheese. Other microbes may assist in Options:
flavor development but do not create these distinctive (A) a-iv, b-i, c-iii, d-ii
“eyes.” (B) a-ii, b-iv, c-i, d-iii
(C) a-i, b-iii, c-iv, d-ii
22. Biogas production and antibiotic production share what
(D) a-iii, b-ii, c-iv, d-i
common feature?
(A) Both rely on microbial metabolism to yield valuable

Ans
products (A) a-iv, b-i, c-iii, d-ii
(B) Both strictly require fungal spores Taq DNA polymerase (iv) extends new strands, primers
(C) They always generate the same by-product (i) define the sequence boundaries, the thermal cycler
(D) Antibiotics are formed by methanogenic archaea (iii) cycles through temperature phases, and dNTPs (ii)


Ans are the raw nucleotides required for strand elongation.
(A) Both rely on microbial metabolism to yield valuable 25. Restriction endonucleases used in biotechnology
products generally recognize:
Biogas arises from anaerobic methanogenic bacteria (A) Entire chromosomes randomly
converting organic waste into methane, whereas (B) Specific palindromic DNA sequences
antibiotics often come from bacterial or fungal (C) Single-stranded RNA sections
secondary metabolism. Despite differing organisms (D) Only methylated cytosines
and processes, both harness microbial capabilities for


Ans
beneficial outputs.

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 PRACTICE PAPER 08

(B) Specific palindromic DNA sequences Vaccines work by training the immune system to
Restriction enzymes typically target short palindromic recognize pathogens without altering the host’s genome.
sequences, cleaving the DNA at or near these sites.
29. Assertion (A) : Bt crops may reduce pesticide usage.
This precision enables reproducible manipulation of
DNA fragments for cloning and genetic engineering Reason (R) : Bt genes in crops confer self-generated
applications. insecticidal properties.
(A) Both Assertion and Reason are true, and Reason is
26. A “cloning vector” is best defined as: the correct explanation
(A) A DNA molecule used to carry a foreign gene into (B) Both Assertion and Reason are true, but Reason is
a host cell not the correct explanation
(B) A virus lethal to all cells (C) Assertion is true but Reason is false
(C) A protein that blocks DNA replication (D) Both Assertion and Reason are false
(D) A chemical that dissolves cell walls

Ans


Ans (A) Both Assertion and Reason are true, and Reason is
(A) A DNA molecule used to carry a foreign gene into the correct explanation
a host cell Bt crops express Cry proteins toxic to specific pests,
Cloning vectors (e.g., plasmids) shuttle target DNA diminishing reliance on external insecticides. Hence,
fragments into suitable host organisms for replication the reason (expression of Bt genes) logically explains the
and possibly expression. They typically include an drop in pesticide needs, affirming the assertion.
origin of replication, selectable markers, and unique
30. “Mutualism” is the interaction where:
restriction sites.
(A) Both species benefit
27. Which is NOT an intended goal of developing transgenic (B) One species benefits, other is unaffected
plants? (C) One species benefits, other is harmed
(A) Enhanced nutritional value (D) Both species are harmed
(B) Greater stress tolerance

Ans
(C) Increased greenhouse gas emission
(D) Pest resistance (A) Both species benefit
Mutualism involves two species interacting


Ans advantageously, such as pollinators receiving nectar
(C) Increased greenhouse gas emission while aiding plant reproduction. Each party derives
Transgenic plants generally aim to improve crop benefits that enhance survival and/or reproductive
yield, resilience, and nutritional content. Engineering success.
them to elevate greenhouse gas emissions would be
31. The “carrying capacity” of an environment indicates:
counterproductive and is not a recognized objective of
plant biotechnology. (A) The total annual birth rate of a species
(B) Maximum population size sustainably supported
28. Compare gene therapy with vaccination. Which by resources
statement is correct? (C) The universal fundamental niche for all organisms
(A) Both involve permanent changes to recipient DNA (D) How fast a population can reproduce with unlimited
(B) Gene therapy replaces defective genes; vaccination resources
triggers an immune response

Ans
(C) Vaccines restore nonfunctional genes in pathogens
(D) Gene therapy relies on antibody formation (B) Maximum population size sustainably supported by
exclusively resources
Carrying capacity represents the equilibrium number


Ans of individuals that a habitat’s resources can maintain
(B) Gene therapy replaces defective genes; vaccination indefinitely without environmental degradation,
triggers an immune response balancing births, deaths, immigration, and emigration.
Gene therapy attempts to fix or substitute faulty genes
32. Interspecific competition arises when:
in patients, addressing underlying genetic disorders.
(A) Organisms of the same species vie for resources

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(B) Two different species contest limited resources (A) 2 → 1 → 3 → 4

(C) One organism directly benefits another with no India’s Wildlife Protection Act laid groundwork for
cost formal protections. Subsequent expansions led to
(D) Predators consume prey species instantly creating National Parks, initiating Biosphere Reserves,


Ans and finally designating specific wetlands as Ramsar sites,
reflecting growing conservation awareness over time.
(B) Two different species contest limited resources
Interspecific competition occurs among distinct species 36. Which statements about biodiversity hotspots are true?
that require overlapping resources (food, shelter, nesting 1. They contain many endemic species
sites). It can shape community structure and drive 2. They face severe habitat losses
evolutionary adaptations to reduce direct competition. 3. All hotspots have tundra conditions
4. The Western Ghats is one such hotspot
33. In an ecosystem, decomposition is mainly carried out (A) 1, 2, and 4
by: (B) 1, 2, and 3
(A) Apex predators (C) 2, 3, and 4
(B) Primary consumers (D) 1, 3, and 4
(C) Decomposers like bacteria and fungi
(D) Keystone species only

Ans

Ans (A) 1, 2, and 4

Hotspots host high endemism (1) and endure substantial
(C) Decomposers like bacteria and fungi habitat threats (2). They can occur in diverse climates,
Bacteria and fungi break down dead organic material, not exclusively tundra (3 is incorrect). India’s Western
recycling nutrients back into the ecosystem. This Ghats is recognized internationally as one such hotspot
fundamental process sustains soil fertility and supports (4).
further productivity at producer levels.
37. Assertion (A) : Sacred groves often protect rare or
34. Which is NOT generally considered a core component endangered species.
of an ecosystem? Reason (R) : Sacred groves are prime targets for
(A) Biotic factors commercial logging.
(B) Abiotic factors (A) Both Assertion and Reason are true, and Reason is
(C) Reliable energy source the correct explanation
(D) Infinite top-level consumers (B) Both Assertion and Reason are true, but Reason is


Ans not the correct explanation
(D) Infinite top-level consumers (C) Assertion is true but Reason is false
Ecosystems require living (biotic) components, (D) Both Assertion and Reason are false
nonliving (abiotic) elements, and an energy source

Ans
(often sunlight). Predator populations are naturally (C) Assertion is true but Reason is false
limited by available prey and habitat capacity. No Sacred groves remain undisturbed due to religious or
consumer population remains infinite. cultural practices, safeguarding diverse species. They
35. Arrange these conservation initiatives in historical are typically off-limits to logging, making the reason
sequence (India-based example): incorrect.
1. Creation of National Parks 38. Why is the scrotum kept at a temperature slightly lower
2. Wildlife Protection Act than body temperature?
3. Biosphere Reserves establishment (A) To ensure poor sperm viability
4. Ramsar Wetlands designation (B) To facilitate optimal spermatogenesis
(A) 2 → 1 → 3 → 4 (C) To prevent testicular descent
(B) 1 → 2 → 4 → 3 (D) To accelerate testosterone breakdown
(C) 2 → 3 → 1 → 4
(D) 4 → 1 → 2 → 3

Ans

Ans (B) To facilitate optimal spermatogenesis

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 PRACTICE PAPER 08

A lower temperature in the scrotum is crucial for proper caused by dermatophytes. The physician explained that
sperm production and development. Excess heat can ringworm is contagious and spreads through direct
damage sperm, reducing fertility, so the testes remain contact with infected skin or contaminated objects like
outside the abdomen at cooler conditions. towels and clothing. Priya was advised to maintain
good hygiene, keep the affected area clean and dry, and
39. Match these STIs with their causative organisms: use antifungal creams to treat the infection. She also
Column I Column II learned that adopting preventive measures, such as
a. Gonorrhea i. Treponema pallidum disinfecting equipment, wearing breathable clothing,
and avoiding prolonged dampness on skin, is crucial to
b. Chlamydia ii. Neisseria gonorrhoeae
limit transmission. As Priya recovered, she recognized the
c. Syphilis iii. Chlamydia trachomatis importance of awareness, early diagnosis, and consistent
d. Genital herpes iv. Herpes simplex virus treatment in managing fungal infections. This experience
Options: underscored that fungal infections can recur without
(A) a-ii, b-iii, c-i, d-iv vigilance.
(B) a-i, b-ii, c-iv, d-iii
41. Ringworm, as seen in Priya’s case, is caused by a:
(C) a-iii, b-ii, c-i, d-iv
(A) Virus
(D) a-iv, b-iii, c-ii, d-i
(B) Bacterium


Ans (C) Fungus
(A) a-ii, b-iii, c-i, d-iv (D) Protozoan
Gonorrhea is caused by Neisseria gonorrhoeae,

Ans
Chlamydia by Chlamydia trachomatis, Syphilis by
(C) Fungus
Treponema pallidum, and Genital herpes by Herpes
Ringworm is a misnomer for dermatophytosis—a
simplex virus. Recognizing the distinct pathogens
fungal infection affecting keratinized tissues like skin,
ensures accurate diagnosis and management.
hair, and nails. No actual worm is involved; the fungus
40. Which statements about fertilization in angiosperms are creates ring-shaped lesions, giving rise to the name.
correct?
42. What preventive measure did Priya learn was essential
1. Pollen tube discharges two male gametes
to impede ringworm spread?
2. One male gamete fuses with polar nuclei
(A) Sharing unwashed clothing
3. Both male gametes fertilize separate eggs
(B) Keeping the affected region dry
4. Double fertilization produces zygote and
(C) Ignoring minor rashes
endosperm
(D) Using only antibiotics for a few days
(A) 1, 2, and 4
(B) 2, 3, and 4

Ans
(C) 1, 3, and 4 (B) Keeping the affected region dry
(D) 1, 2, and 3 Fungi thrive in moist environments. By keeping the area


Ans dry and clean, Priya limits fungal growth. Additional
hygiene measures, such as disinfecting shared items,
(A) 1, 2, and 4
further reduce transmission risks.
In double fertilization, one male gamete fertilizes the
egg, producing the zygote, and the other merges with 43. Ringworm typically spreads through:
the polar nuclei to form endosperm. Thus, statements (A) A hereditary gene from parents
1, 2, and 4 are correct. Statement 3 is incorrect because (B) Direct or indirect contact with fungal spores
there is only one egg cell involved. (C) Only air droplets in crowded spaces
(D) Contaminated water from deep wells


Direction :Carefully read the case study provided and then
thoroughly answer the subsequent five questions.

Ans
Priya, a high school athlete, noticed persistent itching (B) Direct or indirect contact with fungal spores
and circular rashes on her forearm after sharing sports Dermatophytes transfer via direct skin-to-skin contact
equipment. Concerned, she visited a dermatologist or indirectly through contaminated objects (e.g., towels,
who diagnosed ringworm, a common fungal infection

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floors, clothing). Maintaining hygiene and avoiding conventional interventions are limited. Through his study,
shared unclean materials lowers infection likelihood. Arjun recognized how biotechnology can bolster food
nutrition yet requires rigorous testing and responsible
44. Why might ringworm recur if precautions lapse? implementation to ensure sustainability. He understood
(A) Fungal spores can remain dormant and reactivate that community acceptance remains equally important.
(B) Antibiotics ensure lifetime immunity
(C) It never reappears once treated 46. What nutritional advantage does Golden Rice provide?
(D) There is a universal vaccine available (A) Higher carbohydrate content


Ans (B) Increased beta-carotene for Vitamin A
(C) Elimination of protein allergens
(A) Fungal spores can remain dormant and reactivate (D) Complete removal of dietary fats
Inadequate or inconsistent antifungal treatment allows
some spores to survive on the host or surfaces. These

Ans
dormant spores can cause reinfection. Antibiotics do (B) Increased beta-carotene for Vitamin A
not target fungi, and no widely used ringworm vaccine Golden Rice was engineered to synthesize beta-carotene
currently exists. in the endosperm. Beta-carotene is a precursor to
Vitamin A, helping to combat Vitamin A deficiency,
45. Assertion (A) : Adequate and consistent antifungal especially in regions where dietary intake is insufficient.
treatment is crucial for clearing ringworm.
Reason (R) : One topical application of antifungal cream 47. Which external genes were inserted into Golden Rice to
permanently kills all fungal spores. enable beta-carotene production?
(A) Both Assertion and Reason are true, and Reason is (A) Human genes controlling melanin synthesis
the correct explanation (B) Genes from daffodil and a bacterium
(B) Both Assertion and Reason are true, but Reason is (C) Fungal antibiotic genes
not the correct explanation (D) Algal bioluminescent genes
(C) Assertion is true but Reason is false

Ans
(D) Both Assertion and Reason are false
(B) Genes from daffodil and a bacterium


Ans Golden Rice employs two major foreign genes: one from
(C) Assertion is true but Reason is false daffodil and another from Erwinia uredovora, each
Continuous use of antifungal agents over the contributing enzymes required for the beta-carotene
recommended duration is necessary for effective biosynthetic pathway in rice grains.
clearance. A single application seldom eliminates the
48. Why do some critics question Golden Rice’s
fungus completely, given its potential for persistence in
skin layers or on contaminated surfaces. effectiveness?
(A) They claim beta-carotene lacks nutritional value


Direction :Carefully read the case study provided and then (B) Concerns about biosafety, ecological impact, and
thoroughly answer the subsequent five questions. seed monopoly
Arjun, a student researching global malnutrition, (C) It solves all malnutrition issues globally
discovered Golden Rice, genetically engineered to (D) Beta-carotene mutates into harmful toxins
produce beta-carotene in the rice endosperm. Deficiency

Ans
of Vitamin A causes night blindness and other health
issues, particularly in developing countries. Scientists (B) Concerns about biosafety, ecological impact, and
introduced genes from daffodil and a bacterium into seed monopoly
the rice genome to enable beta-carotene synthesis. This Opponents worry about potential unintended
biofortified rice aims to complement dietary strategies consequences, including environmental spread of
and supplementation programs, addressing Vitamin transgenes, reliance on patented seeds, and possible
A deficiency in vulnerable populations. Critics raise risks not fully assessed. While Golden Rice may help
concerns about biosafety, environmental impact, and address Vitamin A deficiency, these concerns fuel
dependence on genetically modified seeds. However, debates over its widespread adoption.
proponents emphasize the potential public health benefits, 49. Which statements are correct about Golden Rice?
seeing Golden Rice as a practical solution, especially where 1. It is biofortified to combat Vitamin A deficiency

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 PRACTICE PAPER 08

2. It faces no controversies
3. It involves gene insertion into the rice genome
4. It can replace a balanced diet entirely
(A) 1 and 3 only
(B) 2 and 3 only
(C) 1, 2, and 4
(D) 2, 3, and 4


Ans
(A) 1 and 3 only
Golden Rice was developed to increase beta-carotene
levels (1) through insertion of specific genes (3). It
remains controversial (2 is false) and cannot wholly
replace balanced diets (4 is false).

50. Assertion (A) : Bacteriological can help counter

micronutrient deficiencies in populations.
Reason (R) : Bacteriological eliminates the need for
diverse diets or supplements.
(A) Both Assertion and Reason are true, and Reason is
the correct explanation
(B) Both Assertion and Reason are true, but Reason is
not the correct explanation
(C) Assertion is true but Reason is false
(D) Both Assertion and Reason are false


Ans
(C) Assertion is true but Reason is false
While bacteriological enhances nutrient content in
staple foods, it does not replace the importance of
varied diets and supplementation. A holistic approach,
including balanced nutrition and targeted health
interventions, remains crucial for effectively reducing
micronutrient deficiencies.

*************

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PRACTICE PAPER 09

1. Which component in a mature pollen grain is crucial for (A) 1-d, 2-c, 3-a, 4-b
delivering male gametes into the embryo sac? (B) 1-b, 2-a, 3-d, 4-c
(A) Generative cell (C) 1-d, 2-a, 3-c, 4-b
(B) Vegetative cell (D) 1-c, 2-d, 3-b, 4-a
(C) Stigma receptor

Ans
(D) Polar nucleus
(A) 1-d, 2-c, 3-a, 4-b


Ans The anther forms pollen grains (d). The stigma is
(B) Vegetative cell specialized to receive pollen (c). The ovary contains
The vegetative cell forms the pollen tube that transports ovules and matures into fruit (a). The filament elevates
the generative cell’s nuclei into the embryo sac. Its the anther for effective pollen release (b). These
cytoplasmic extension guides the sperm cells to the coordinated roles ensure successful pollination and
ovule. This specialized mechanism ensures effective fertilization in flowering plants. Thus, reproduction
fertilization in flowering plants, making the vegetative proceeds with precision effectively.
cell essential for successful sexual reproduction. Thus, it
4. Which of the following is NOT an outbreeding device in
is indispensable overall.
flowering plants?
2. Which structure in a typical angiosperm ovule develops (A) Dichogamy ensuring temporal separation
into the seed coat after fertilization? (B) Cleistogamy promoting self-pollination
(A) Nucellus (C) Self-incompatibility preventing self-fertilization
(B) Integuments (D) Heterostyly favoring cross-pollination
(C) Synergids

Ans
(D) Polar nuclei
(B) Cleistogamy promoting self-pollination


Ans Cleistogamy involves closed flowers that self-
(B) Integuments pollinate without pollen transfer from another plant.
Integuments cover and protect the developing embryo This phenomenon increases inbreeding rather than
sac. After fertilization, these layers harden and transform outbreeding. Other listed mechanisms restrict or
into the seed coat, providing physical defense and discourage self-fertilization, encouraging genetic
preventing desiccation. This transformation ensures the diversity. Therefore, cleistogamy is not an outbreeding
viability of the embryo, which is crucial for germination device but instead ensures autonomous self-pollination
and the continuation of the plant’s life cycle overall. Vital in specific species. It bypasses cross-pollination entirely
for reproduction. too completely.

3. Match the floral components in Column I with their 5. Identify the primary site of spermatogenesis in human
primary roles in Column II: males.
(A) Seminiferous tubules
Column I Column II
(B) Epididymis
1. Anther a. Female reproductive organ (C) Vas deferens
containing ovules (D) Ejaculatory ducts
2. Stigma b. Supports the anther


Ans
3. Ovary c. Receives pollen
(A) Seminiferous tubules
4. Filament d. Produces pollen grains
Seminiferous tubules, located within the testes, are the
Options: specialized structures where spermatogenesis begins.

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 PRACTICE PAPER 09

Germ cells within their lining differentiate into mature

Ans

sperm through several stages. Sertoli cells provide (B) Luteinizing Hormone (LH)
nourishment, and the tubular environment supports A sharp rise in LH around the mid-cycle triggers
sequential development of spermatozoa until they can ovulation by causing the dominant follicle to rupture
migrate to the epididymis for final maturation. This and release the secondary oocyte. FSH helps develop
process is crucial. follicles, but LH provides the final signal for ovulatory
events. This LH surge is critical for successful fertility in
6. In humans, the acrosome of a sperm is primarily derived
the female reproductive cycle. It ensures reproduction.
from which cellular organelle?
(A) Golgi complex 9. Which contraceptive method provides dual protection
(B) Lysosome against unintended pregnancy and most STDs?
(C) Endoplasmic reticulum (A) Oral contraceptive pills
(D) Mitochondrion (B) Condom


Ans (C) Intrauterine devices
(D) Tubal ligation
(A) Golgi complex
During spermiogenesis, the Golgi complex in the

Ans
developing spermatid forms the acrosome. This cap-like (B) Condom
structure contains enzymes that help sperm penetrate Condoms serve as a physical barrier that blocks the
the egg’s protective layers during fertilization. The exchange of semen, vaginal fluids, and infectious
transformation of Golgi vesicles into the acrosome agents. Unlike oral pills or intrauterine devices, they can
ensures that the sperm possesses the necessary protect against sexually transmitted infections while
enzymatic tools for successful entry. It is indispensable. also reducing the risk of unintended pregnancy. Their
dual benefit makes them widely recommended for
7. Assertion (A) : The menstrual cycle in human females
reproductive health. It’s highly effective.
is regulated by hormones from the hypothalamus,
pituitary, and ovaries. 10. Which test-based procedure examines fetal cells in
Reason (R) : High levels of FSH and LH inhibit ovulation. amniotic fluid to detect chromosomal abnormalities?
(A) Both Assertion and Reason are true, and Reason is (A) Ultrasound
the correct explanation. (B) Chorionic villus sampling
(B) Both Assertion and Reason are true, but Reason is (C) Amniocentesis
not the correct explanation. (D) Triple marker test
(C) Assertion is true, but Reason is false.


Ans
(D) Assertion is false, but Reason is true.
(C) Amniocentesis


Ans
Amniocentesis involves withdrawing a small volume of
(C) Assertion is true, but Reason is false amniotic fluid containing fetal cells. These cells are then
Hormones from the hypothalamus, pituitary, and cultured and analyzed for chromosomal abnormalities
ovaries orchestrate the menstrual cycle. However, high like Down’s syndrome. This procedure allows early
FSH and LH levels actually trigger ovulation rather than detection of genetic disorders but carries a slight risk of
inhibit it. Therefore, while the assertion is accurate, complications, including miscarriage, underscoring the
the reason presented contradicts the known hormonal need for medical counseling. It is informative.
surge necessary for follicular rupture and egg release.
This ensures proper timing overall. 11. Which strategy is recommended to prevent pregnancy
following unprotected intercourse?
8. Which hormone predominantly triggers the surge (A) Tubectomy
leading to ovulation in the human female reproductive (B) Vasectomy
cycle? (C) Emergency contraceptive pill
(A) Follicle Stimulating Hormone (FSH) (D) Copper-T insertion after several months
(B) Luteinizing Hormone (LH)


Ans
(C) Progesterone
(D) Oxytocin (C) Emergency contraceptive pill

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Emergency contraceptive pills provide a short window 3. Polygenic c. Two alleles fully express in
to inhibit or delay ovulation. They are taken soon inheritance heterozygote
after unprotected intercourse, lowering the chance of
4. Codominance d. More than two allelic
implantation. Tubectomy and vasectomy are permanent
forms for a gene
solutions, not immediate measures. Copper-T insertion
must happen promptly for post-coital contraception, Options:
making emergency pills the optimal recommended (A) 1-b, 2-d, 3-a, 4-c
strategy. It is essential. (B) 1-a, 2-c, 3-b, 4-d
(C) 1-b, 2-a, 3-d, 4-c
12. In incomplete dominance, the F1 hybrid exhibits a (D) 1-c, 2-d, 3-a, 4-b
phenotype that is:


Ans
(A) Identical to the dominant parent
(B) Intermediate between both parents (A) 1-b, 2-d, 3-a, 4-c
(C) Identical to the recessive parent Pleiotropy (1-b) occurs when a single gene impacts
(D) Completely blended without parental traits multiple traits. Multiple alleles (2-d) indicate a gene
with more than two variants. Polygenic inheritance


Ans
(3-a) involves multiple genes contributing to a single
(B) Intermediate between both parents phenotype. Codominance (4-c) features both alleles
In incomplete dominance, neither allele is fully being expressed in the heterozygote equally. These
dominant, causing the offspring’s phenotype to appear definitions clarify core genetic principles thoroughly.
between those of the homozygous parents. Classic
examples include the pink flowers from red and white 15. Which blood group genotype exemplifies codominance
parental crosses in snapdragons. This demonstrates how in humans?
partial expression of each allele produces an intermediate (A) IAIA
phenotype. It emphasizes partial dominance. (B) IBi
(C) IAIB
13. Which of the following conditions is NOT an example (D) ii
of a Mendelian disorder?


Ans
(A) Thalassemia
(B) Haemophilia (C) IAIB
(C) Sickle-cell anemia In the IAIB genotype, both A and B alleles produce
(D) Diabetes mellitus (Type 2) distinct antigens on red blood cells. Unlike incomplete
dominance, codominance ensures both alleles


Ans
are expressed equally, resulting in a phenotype
(D) Diabetes mellitus (Type 2) that simultaneously displays A and B blood group
Classical Mendelian disorders such as thalassemia, characteristics rather than blending them into an
haemophilia, and sickle-cell anemia follow inheritance intermediate form. This maintains clear distinction.
patterns tied to single-gene mutations. Type 2 diabetes,
however, is multifactorial, resulting from genetic 16. Identify the type of nucleic acid that carries amino acids
predisposition combined with environmental triggers. to the ribosome during translation.
It does not strictly follow simple dominant or recessive (A) mRNA
inheritance rules like Mendelian disorders. Hence, it lies (B) tRNA
outside Mendelism. (C) rRNA
(D) snRNA
14. Match the following genetic terms in Column I with


Ans
their descriptions in Column II:
(B) tRNA
Column I Column II Transfer RNA (tRNA) functions as an adaptor
1. Pleiotropy a. Multiple genes affect one molecule. It recognizes codons on mRNA and delivers
trait the corresponding amino acid to the ribosome. This
2. Multiple alleles b. One gene influences bridging role ensures that each codon is translated into
multiple traits

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 PRACTICE PAPER 09

its specific amino acid, thereby building the polypeptide (B) Both Assertion and Reason are true, but Reason is
chain in the correct order. It is critical for translation. not the correct explanation.
(C) Assertion is true, but Reason is false.
17. Which enzyme is responsible for unwinding the DNA (D) Assertion is false, but Reason is true.
double helix during replication?
(A) DNA helicase

Ans
(B) DNA polymerase I (B) Both Assertion and Reason are true, but Reason is
(C) RNA polymerase not the correct explanation
(D) DNA ligase DNA polymerase III extends the new strand exclusively


Ans from 5’ to 3’. It also possesses 3’→5’ exonuclease
activity to correct errors, but that does not explain why
(A) DNA helicase elongation cannot occur 3’→5’. The enzyme’s active site
DNA helicase unwinds the double helix by breaking only catalyzes nucleotide addition at the 3’ hydroxyl
hydrogen bonds between complementary bases, end. This fundamental constraint defines replication
generating the replication fork. This allows DNA efficiency.
polymerases to access single-stranded templates.
Without helicase activity, replication cannot proceed 20. Which concept refers to the random changes in allele
efficiently, as the DNA strands must separate before frequencies within a population, especially in small
new nucleotides can be added correctly. It is pivotal for populations?
fidelity. (A) Natural selection
(B) Genetic drift
18. Select the correct combination of statements regarding (C) Gene flow
the lac operon in E. coli: (D) Mutation pressure
1. Lac operon is an inducible system.
2. The structural genes are expressed only in the

Ans
absence of lactose. (B) Genetic drift
3. The lac repressor binds to the operator region. Genetic drift involves chance events that alter allele
4. Lactose acts as an inducer by inactivating the frequencies, which can have a dramatic effect in
repressor. smaller populations. Unlike natural selection, which
5. High glucose levels inhibit adenylate cyclase, is driven by differential reproductive success, genetic
lowering cAMP. drift is random. Over time, it may fix certain alleles or
(A) 1, 3, and 4 are correct eliminate others without regard to adaptive value. It
(B) 2, 4, and 5 are correct occurs unpredictably too.
(C) 1, 2, and 3 are correct
21. According to modern synthetic theory, what primarily
(D) 1, 3, 4, and 5 are correct
drives evolutionary change?


Ans (A) Sudden large mutations alone
(D) 1, 3, 4, and 5 are correct (B) Migration without genetic recombination
Lac operon is inducible (1). The repressor binds to the (C) Recombination, mutations, and natural selection
operator (3). Lactose inactivates the repressor (4). High (D) Spontaneous generation of species
glucose reduces cAMP, affecting operon activation

Ans
(5). The operon’s structural genes are predominantly
expressed in the presence of lactose, making statement (C) Recombination, mutations, and natural selection
2 incorrect. Thus, options 1,3,4,5 are valid. This ensures Modern evolutionary synthesis integrates Darwin’s
precise regulation. natural selection with Mendelian genetics, emphasizing
that continuous variation arises from mutations and
19. Assertion (A) : DNA polymerase III in prokaryotes can genetic recombination. Natural selection then acts on
synthesize new DNA only in the 5’→3’ direction. these variations, shaping populations over time. This
Reason (R) : DNA polymerase III also has 3’→5’ combined perspective accounts for both gradual and
exonuclease activity for proofreading. sometimes rapid evolutionary changes in species. It
(A) Both Assertion and Reason are true, and Reason is remains widely accepted today.
the correct explanation.

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22. Arrange the following events in the correct chronological mosquitoes, while kala-azar spreads via sandflies.
sequence of human evolution: Typhoid is a bacterial infection transmitted through
1. Development of bipedalism contaminated food or water. Thus, Aedes is specifically
2. Emergence of Homo habilis linked with dengue fever. It poses public health risks.
3. Use of fire by Homo erectus
25. Which cells are primarily responsible for producing
4. Neanderthal phases
Options: antibodies?
(A) 1 → 2 → 3 → 4 (A) T lymphocytes
(B) 2 → 1 → 4 → 3 (B) B lymphocytes
(C) 1 → 3 → 2 → 4 (C) Neutrophils
(D) 3 → 1 → 2 → 4 (D) Eosinophils

Ans

Ans

(A) 1 → 2 → 3 → 4 (B) B lymphocytes

Bipedalism evolved early in hominins. Homo habilis, B lymphocytes differentiate into plasma cells that secrete
often called the “handy man,” emerged next. Homo specific antibodies. These antibodies bind antigens,
erectus harnessed fire for cooking and protection. marking them for destruction or neutralization. T
Neanderthals appeared later, showcasing advanced lymphocytes coordinate immune responses but do not
cultural traits. This sequence reflects the broad timeline produce antibodies. Neutrophils and eosinophils are
of key milestones in human evolutionary history. It granulocytes that perform phagocytic or other immune
highlights progressive anatomical and behavioral shifts functions rather than antibody production. They are
overall. essential for defense.

26. Which type of immunity is conferred when a person

23. Which prehistoric creature is considered a transitional
link between reptiles and birds? receives antibodies through breast milk?
(A) Archaeopteryx (A) Active immunity
(B) Australopithecus (B) Passive immunity
(C) Peking man (C) Autoimmunity
(D) Cro-Magnon man (D) Innate immunity

Ans

Ans

(A) Archaeopteryx (B) Passive immunity

Archaeopteryx possessed features of both reptiles Breast milk contains maternal antibodies, especially
(teeth, long tail) and birds (feathers, wings), making IgA, which are passed to the infant, offering temporary
it a classic transitional fossil. Its discovery provided protection without stimulating the baby’s own
strong evidence for evolutionary theory, illustrating immune system to produce those antibodies. Because
how incremental changes can bridge major taxonomic the antibodies are acquired externally, this defense
groups. Hence, it remains a pivotal example of an mechanism is classified as passive, affording short-term
intermediate form in vertebrate history today. immune support to newborns. It gradually wanes over
time.
24. Which of the following diseases is transmitted by the
27. Which microorganism is primarily used in the
Aedes mosquito?
(A) Malaria commercial production of ethanol?
(B) Kala-azar (A) Lactobacillus acidophilus
(C) Dengue (B) Saccharomyces cerevisiae
(D) Typhoid (C) Penicillium chrysogenum
(D) Acetobacter aceti


Ans


Ans
(C) Dengue
The Aedes mosquito transmits dengue virus, which (B) Saccharomyces cerevisiae
causes high fever, severe headache, and joint pain. Saccharomyces cerevisiae, commonly known as baker’s
In contrast, malaria is transmitted by Anopheles yeast, ferments sugars to produce ethanol and carbon
dioxide. This process underlies brewing and other

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 PRACTICE PAPER 09

industrial fermentation. Lactobacillus acidophilus is (D) Reverse transcriptase

used in dairy products, Penicillium chrysogenum in

Ans
penicillin production, and Acetobacter aceti in vinegar
formation via acetic acid fermentation. It ensures large- (B) Restriction endonuclease
scale alcohol production. Restriction endonucleases recognize specific
palindromic DNA sequences and cleave the
28. Why are biofertilizers like Rhizobium beneficial in phosphodiester backbone at or near these sites. They
agriculture? serve as molecular scissors in genetic engineering,
(A) They consume soil nutrients enabling precise insertion or removal of DNA
(B) They reduce soil aeration fragments. This specificity underpins recombinant
(C) They fix atmospheric nitrogen DNA technology and is essential for constructing
(D) They cause harmful root infections desired genetic combinations. It revolutionized modern


Ans biotechnology.

(C) They fix atmospheric nitrogen 31. Which of the following vectors is commonly used in
Rhizobium resides in root nodules of legumes and cloning genes in bacteria?
converts atmospheric nitrogen into usable ammonia, (A) Ti plasmid
enriching soil fertility naturally. This symbiotic (B) Bacteriophage lambda
relationship decreases reliance on chemical fertilizers (C) pBR322 plasmid
and benefits both plants and soil health. By transforming (D) Yeast artificial chromosome
inert nitrogen into a bioavailable form, biofertilizers

Ans
boost crop yield sustainably. It promotes eco-friendly
agriculture. (C) pBR322 plasmid
pBR322 is a widely used bacterial cloning plasmid
29. Assertion (A) : Microbes can be used as bio-control containing antibiotic resistance markers for selection. It
agents to reduce chemical pesticide usage. enables the replication and maintenance of foreign DNA
Reason (R) : Certain bacteria, fungi, and viruses fragments in Escherichia coli. Though other vectors like
selectively infect pests without harming other organisms. bacteriophage lambda and Ti plasmid have applications,
(A) Both Assertion and Reason are true, and Reason is pBR322 remains a foundational tool in recombinant
the correct explanation. DNA technology. It pioneered modern cloning.
(B) Both Assertion and Reason are true, but Reason is
32. Which polymerase is key for synthesizing DNA from an
not the correct explanation.
(C) Assertion is true, but Reason is false. RNA template during cDNA formation?
(D) Assertion is false, but Reason is true. (A) DNA polymerase I
(B) Reverse transcriptase


Ans (C) RNA polymerase II
(A) Both Assertion and Reason are true, and Reason is (D) T4 DNA ligase
the correct explanation

Ans
Biological control agents like Bacillus thuringiensis
produce toxins that target specific insects. This (B) Reverse transcriptase
selectivity avoids non-target species, reducing the Reverse transcriptase, isolated from retroviruses,
ecological and health risks associated with chemical synthesizes complementary DNA (cDNA) from an
pesticides. Hence, the reason directly supports the RNA template. This enzyme’s unique ability underpins
assertion, confirming the efficiency of microbes in eco- essential techniques such as RT-PCR, allowing
friendly pest management. It aligns with sustainable researchers to study gene expression and produce DNA
agriculture principles. copies of mRNA. Its discovery revolutionized molecular
biology and biotechnology research significantly. It
30. Which enzyme is used to cut DNA at specific recognition remains central to cDNA methodologies.
sites in genetic engineering?
33. Which transgenic crop expresses the Cry protein to
(A) DNA ligase
(B) Restriction endonuclease resist insect pests?
(C) RNA polymerase (A) Golden Rice
(B) Bt Cotton

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(C) Flavr Savr Tomato

Ans

(D) Herbicide-tolerant Soybean (B) Population density


Ans Population density measures how many individuals
inhabit a given area, reflecting environmental capacity
(B) Bt Cotton
and species interactions. It influences resource
Bt cotton is engineered with genes from Bacillus
competition, mating opportunities, and overall survival.
thuringiensis that produce Cry proteins, toxic to
In contrast, birth and death rates indicate population
certain insect larvae. This built-in defense reduces
change, while age distribution describes the proportion
chemical pesticide usage and protects yields. Golden
of different age classes in a population. It shapes
Rice enhances vitamin A, Flavr Savr Tomato delays
ecological dynamics.
spoilage, and herbicide-tolerant soybean resists specific
herbicidal compounds. It represents targeted genetic 37. Which interspecific interaction benefits both species
protection. involved?
(A) Predation
34. How does gene therapy aim to treat genetic disorders?
(B) Competition
(A) By amplifying faulty alleles
(C) Mutualism
(B) By introducing functional genes
(D) Parasitism
(C) By extracting all defective cells
(D) By halting cell division indefinitely

Ans

Ans (C) Mutualism

In mutualism, each species gains a net benefit from the
(B) By introducing functional genes
relationship, such as nutrient exchange, pollination
Gene therapy attempts to replace or supplement
assistance, or protection. For instance, pollinators
defective genes with healthy copies, restoring normal
receive food while plants achieve fertilization. Predation,
protein production. This can alleviate or even cure
competition, and parasitism are not mutually beneficial
genetic disorders at their molecular root. It does not
interactions but instead involve harm or resource rivalry
amplify faulty alleles, remove all cells, or permanently
for at least one participant overall.
halt cell division, focusing instead on functional gene
restoration. It’s a targeted approach. 38. Which trophic level contains organisms that directly
utilize solar energy to synthesize organic compounds?
35. Which of the following is NOT a benefit of genetically
(A) Primary consumers
modified organisms (GMOs) in agriculture?
(B) Primary producers
(A) Increased nutrient content in crops
(C) Secondary consumers
(B) Resistance to pests and diseases
(D) Tertiary consumers
(C) Elimination of the need for any fertilizers
(D) Tolerance to specific herbicides

Ans

Ans (B) Primary producers

Primary producers, such as green plants and algae,
(C) Elimination of the need for any fertilizers
convert solar energy into chemical energy via
Although GMOs can enhance nutrient profiles, confer
photosynthesis. They form the base of the food chain,
pest resistance, and withstand certain herbicides, they
supporting higher trophic levels. Consumers depend on
do not eliminate fertilizer use entirely. Fertilizers provide
this organic matter, either directly or indirectly, making
essential nutrients like nitrogen and phosphorus. Genetic
producers vital for energy flow in ecosystems. They
modifications can reduce fertilizer requirements but do
underpin ecological sustainability overall.
not abolish them, making (C) an incorrect assumption
about GMOs. Fertilization remains vital for yield. 39. Arrange the following steps of energy flow in sequence,
starting from the sun:
36. Which population attribute refers to the number of
1. Primary consumers feed on producers
individuals per unit area?
2. Solar energy is captured by producers
(A) Birth rate
3. Secondary consumers eat primary consumers
(B) Population density
4. Tertiary consumers feed on secondary consumers
(C) Death rate
Options:
(D) Age distribution

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 PRACTICE PAPER 09

(A) 2→1→3→4 41. Which hormone primarily regulates the maturation of

(B) 1→2→3→4 ovarian follicles according to the case?
(C) 2→3→1→4 (A) Oxytocin
(D) 3→1→2→4 (B) Follicle-stimulating hormone (FSH)


Ans (C) Prolactin
(D) Thyroxine
(A) 2 → 1 → 3 → 4
Energy flow begins as producers capture solar energy (2).

Ans
Primary consumers then feed on these producers (1). (B) Follicle-stimulating hormone (FSH)
Next, secondary consumers eat primary consumers (3), As per the scenario, the doctor highlights pituitary
and tertiary consumers feed on secondary consumers hormones influencing ovarian function. FSH stimulates
(4). This linear sequence illustrates how energy moves the growth and maturation of ovarian follicles, preparing
upward through trophic levels in ecosystems. It them for ovulation. This ensures egg development in
highlights systematic energy transfer. each cycle. High stress can disrupt hormonal balance,
altering FSH levels and causing irregularities like
40. Which area is recognized for exceptionally high levels of Shreya’s prolonged menstrual intervals overall.
species richness and endemism?
(A) Desert biome 42. What lifestyle factor did the doctor emphasize to help
(B) Hotspot stabilize Shreya’s menstrual cycle?
(C) Polar region (A) Excessive exercise
(D) Tundra (B) Skipping meals


Ans (C) Stress management
(D) Frequent caffeine intake
(B) Hotspot
Biodiversity hotspots are regions housing a large

Ans
number of endemic species under threat. They possess (C) Stress management
remarkable species richness yet face habitat loss and The case mentions stress can negatively affect hormonal
other pressures. Desert, tundra, and polar areas typically equilibrium. Proper stress management helps maintain
have fewer species due to extreme conditions. Protecting the hormonal signals controlling the menstrual
hotspots is vital for preserving global biodiversity. They cycle. Simple measures like relaxation exercises, time
demand urgent conservation measures. management, and balanced sleep can stabilize hormone
release, reduce cycle irregularities, and foster better


Direction :Carefully read the case study provided and then overall reproductive health in adolescents. It underpins
thoroughly answer the subsequent five questions. consistent hormonal patterns.
Shreya, a 16-year-old student, recently learned in biology
class about the menstrual cycle and the importance of 43. Which statement best aligns with the importance of
reproductive health. She notices irregularities in her early counseling mentioned in the case?
own cycle, sometimes experiencing prolonged intervals (A) It has no role in adolescent reproductive decisions.
without menstruation. Concerned about potential issues, (B) It prevents any hormonal imbalances from ever
she discusses her situation with a healthcare provider. occurring.
The doctor explains how hormones from the pituitary (C) It empowers adolescents with accurate knowledge
gland regulate ovarian function and the impact of stress and timely support.
on hormonal balance. Shreya is advised to maintain a (D) It is only relevant to married individuals.
balanced diet, manage stress, and track her menstrual

Ans
patterns. She also learns about different contraceptive
methods and the importance of avoiding sexually (C) It empowers adolescents with accurate knowledge
transmitted diseases (STDs). Her doctor emphasizes the and timely support.
significance of early counseling and awareness programs, The doctor stresses that early counseling provides
ensuring adolescents receive accurate information about crucial health information, helping young individuals
reproductive health for better long-term well-being. Such like Shreya navigate concerns regarding contraception,
education fosters confidence, timely medical advice, and STDs, and menstrual irregularities. Correct, age-
responsible reproductive decision-making overall. appropriate knowledge fosters responsible decisions

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page 94 CUET UG Biology

and reduces risks. This guidance is universally helpful, caterpillars damaging the bolls and reduced need for
not restricted by marital status or guaranteeing zero chemical pesticides, which lowers input costs. Some
imbalances. It promotes informed reproductive neighboring farmers express concerns about long-term
autonomy. ecological effects and resistance development among pests.
However, agricultural extension officers highlight the
44. Which preventive measure from the case safeguards importance of integrated pest management, rotating crops,
against both pregnancy and STDs? and maintaining refuge areas. The officials emphasize
(A) Oral contraceptive pills that responsible use of Bt cotton can enhance productivity
(B) Condoms while mitigating pest-related losses in sustainable ways.
(C) Intrauterine devices He remains optimistic about this innovation, mindful of
(D) Hormonal implants risks overall.


Ans
46. Why does Bt cotton produce fewer bollworm-infested
(B) Condoms bolls?
Condoms were implicitly highlighted when the (A) It grows only in winter.
doctor emphasized preventing STDs and unintended (B) It is unable to flower.
pregnancies. They create a physical barrier to block (C) It generates Cry proteins lethal to bollworms.
sperm and pathogens, unlike oral contraceptives or (D) It is sterile and cannot support pest life.
implants, which mainly prevent pregnancy. This dual
function makes condoms an essential and recommended

Ans
option for adolescent sexual health. It promotes holistic (C) It generates Cry proteins lethal to bollworms.
reproductive protection. Bt cotton carries genes from Bacillus thuringiensis,
enabling the plant to produce Cry proteins toxic to
45. Which best describes the role of a balanced diet in certain insects. When bollworms consume the cotton
managing Shreya’s menstrual irregularities? tissue, the toxins disrupt their gut lining, reducing
(A) It increases daily stress hormones. infestations. This built-in pest resistance significantly
(B) It disrupts ovarian hormone production. lowers pesticide requirements and diminishes crop
(C) It supports normal hormonal functions and overall losses from caterpillar damage. It increases yield
health. security.
(D) It is irrelevant to reproductive processes.
47. Which main concern do some neighboring farmers


Ans
have regarding Bt cotton?
(C) It supports normal hormonal functions and overall (A) Total eradication of beneficial soil microbes
health. (B) Guaranteed profit with no risks
A balanced diet ensures essential nutrients for (C) Development of pest resistance over time
maintaining endocrine harmony, stabilizing processes (D) Immediate death of all insect species
like the menstrual cycle. Adequate vitamins and minerals
help preserve healthy ovarian function, while protein

Ans
and carbohydrates provide sustained energy. Good (C) Development of pest resistance over time
nutrition, alongside stress management, can reduce The case highlights neighboring farmers’ worries
cycle disruptions and bolster adolescent reproductive about possible long-term ecological impacts and pest
well-being. It fosters consistent physiological rhythms. adaptation. Continuous exposure to Cry proteins may
select for resistant strains of pests. Integrated pest


Direction :Carefully read the case study provided and then management, including refuge areas and crop rotation,
thoroughly answer the subsequent five questions. helps delay resistance buildup, ensuring the sustained
Bikram, a progressive farmer in a semi-arid region, effectiveness of Bt technology. It safeguards future crop
cultivates cotton to support his family’s livelihood. In stability.
recent years, bollworm infestations have severely reduced
his crop yield, compelling him to explore alternatives. 48. How does Bikram’s adoption of Bt cotton potentially
After attending an agricultural workshop, he decides to lower his input costs?
plant Bt cotton seeds, genetically engineered to produce (A) By stopping plant growth entirely
Cry proteins toxic to certain pests. Bikram notices fewer (B) By eliminating seed expenses

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 PRACTICE PAPER 09

(C) By reducing the need for chemical pesticides

(D) By removing soil nutrients


Ans
(C) By reducing the need for chemical pesticides
Bt cotton’s inbuilt insecticidal property decreases
reliance on expensive pesticides, lowering overall
production costs. Fewer pesticide applications also
reduce labor and environmental impact. Although seeds
might be more costly initially, the decreased chemical
usage and minimized pest damage can offset expenses
and improve Bikram’s profit margins. This enhances
farm sustainability overall.

49. What integrated pest management practice is

recommended alongside Bt cotton?
(A) Continuous monoculture of Bt cotton alone
(B) Overuse of the same Cry gene variety
(C) Incorporation of refuge areas and crop rotation
(D) Immediate switch to entirely different crops


Ans
(C) Incorporation of refuge areas and crop rotation
The extension officers advocate integrated pest
management strategies, including maintaining non-Bt
refuge zones and rotating crops. These measures prevent
the pest population from uniformly adapting to the Cry
protein. By diversifying the selection pressure, pests less
likely develop wide-scale resistance, promoting long-
term efficacy of Bt cotton. It ensures stable, sustainable
control.

50. How might Bikram address his neighbors’ ecological

concerns regarding transgenic crops?
(A) Discontinue all cotton cultivation
(B) Rely solely on chemical pesticides
(C) Follow responsible guidelines and monitoring
(D) Dismiss their concerns as unscientific rumors


Ans
(C) Follow responsible guidelines and monitoring
The scenario underscores that responsible use of Bt
cotton involves adhering to recommended practices,
such as employing refuge areas, crop rotation, and
vigilant monitoring for pest resistance. This balanced
approach addresses ecological and safety concerns.
Transparent communication with local experts helps
build trust and mitigates risks associated with transgenic
technology.

*************

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PRACTICE PAPER 10

1. Which structure in a flowering plant initially receives seed, and the ovary becomes the fruit. Synergids aid
the pollen during pollination? pollen tube guidance but do not become seeds. Hence,
(A) Style fertilized synergids do not develop into seed structures,
(B) Receptacle making option (C) the exception here.
(C) Stigma
4. Which reproductive structure in human males is shared
(D) Filament
by both the urinary and reproductive tracts?


Ans (A) Ureter
(C) Stigma (B) Urethra
The stigma is the top part of the pistil where pollen (C) Epididymis
lands. It often has a sticky surface or specialized cells for (D) Seminal vesicle
trapping pollen grains. Once captured, pollen interacts

Ans
with the stigma’s secretions, aiding germination of the
pollen tube toward the ovary. This step is crucial for (B) Urethra
successful fertilization overall. The urethra in human males serves dual functions:
it conducts urine out of the bladder and also carries
2. Which term describes the practice of preventing self- semen during ejaculation. In contrast, the epididymis is
pollination by timing the release of pollen separately involved in sperm storage, while the ureter connects the
from stigma receptivity? kidney to the bladder. Seminal vesicles produce seminal
(A) Cleistogamy fluid but do not transport urine.
(B) Dichogamy
5. Which hormone promotes the maintenance of the
(C) Geitonogamy
(D) Vivipary endometrium during pregnancy?
(A) Oxytocin


Ans (B) Progesterone
(B) Dichogamy (C) Gonadotropin-releasing hormone
Dichogamy entails a temporal separation between (D) Prolactin
anther dehiscence and stigma receptivity. In protandry,

Ans
anthers mature first, while in protogyny, the stigma is
receptive before pollen release. This strategy promotes (B) Progesterone
outcrossing, reducing self-fertilization. Thus, dichogamy Progesterone, secreted mainly by the corpus luteum
fosters genetic diversity in plant populations by ensuring (and later by the placenta), keeps the uterine lining
pollen transfer between different individuals efficiently. thick and well-vascularized for embryo implantation
and growth. This hormone prevents the shedding of
3. Which of the following does NOT occur after double the endometrium. Insufficient progesterone levels can
fertilization in an angiosperm? lead to early pregnancy failure. Thus, it remains vital for
(A) Formation of diploid zygote gestational support in humans.
(B) Formation of triploid endosperm
6. Which specific part of the testes is lined with germinal
(C) Fertilized synergids growing into seeds
(D) Seed development from the ovule epithelium for spermatogenesis?
(A) Rete testis


Ans (B) Seminiferous tubules
(C) Fertilized synergids growing into seeds (C) Vas deferens
Double fertilization produces a zygote (2n) and triploid (D) Leydig cells region
endosperm (3n). The ovule then develops into the

Ans

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 PRACTICE PAPER 10

(B) Seminiferous tubules

Ans

Spermatogenesis principally occurs in the seminiferous (C) MOET
tubules, whose walls contain spermatogonia and Multiple Ovulation and Embryo Transfer (MOET)
supporting Sertoli cells. Leydig cells, located in the stimulates a high-value female to produce multiple eggs,
interstitial spaces, produce testosterone but do not which are fertilized and later flushed out. These embryos
directly facilitate sperm formation. The rete testis and are transferred to surrogate females for gestation. ZIFT
vas deferens transport sperm but lack the specialized (Zygote Intra-Fallopian Transfer) and GIFT (Gamete
epithelium required for germ cell development. Intra-Fallopian Transfer) differ in placement of zygotes
or gametes, while ICSI is intracytoplasmic sperm
7. Assertion (A) : An oocyte completes its second meiotic
injection.
division only after fertilization.
Reason (R) : High estrogen levels alone are responsible 10. Which is NOT a recommended method to avoid
for meiotic completion in human oocytes. unwanted pregnancies?
(A) Both Assertion and Reason are true, and Reason is (A) IUD insertion
the correct explanation. (B) Oral contraceptive pills
(B) Both Assertion and Reason are true, but Reason is (C) Emergency contraceptive pills
not the correct explanation. (D) Semen transfusion therapy
(C) Assertion is true, but Reason is false.


Ans
(D) Assertion is false, but Reason is true.
(D) Semen transfusion therapy


Ans
Common contraception options include IUDs, oral
(C) Assertion is true, but Reason is false. contraceptive pills, and emergency pills, all of which
In human females, the secondary oocyte is arrested at prevent or reduce the chance of pregnancy. “Semen
metaphase II and completes meiosis II only upon sperm transfusion therapy” is not recognized or recommended
entry. This event is triggered by factors associated with for preventing pregnancy. Contraceptive measures
fertilization, not merely elevated estrogen. Thus, the function by blocking fertilization, altering hormone
assertion is correct, but the reason given does not align levels, or inhibiting implantation, none of which
with the known biological trigger mechanism. involves semen transfusions.
8. Which STD can be largely prevented by the hepatitis B 11. In a typical dihybrid cross, what is the phenotypic ratio
vaccine due to its viral etiology? in the F2 generation under independent assortment?
(A) Gonorrhea (A) 3:1
(B) Syphilis (B) 9:3:3:1
(C) Hepatitis B infection (C) 1:2:1
(D) Chlamydial infection (D) 2:1:1


Ans

Ans
(C) Hepatitis B infection (B) 9:3:3:1
Hepatitis B, caused by the hepatitis B virus, is often For two independently assorting genes, each with
considered alongside STDs because it can be transmitted dominant and recessive alleles, Mendel’s dihybrid cross
via sexual contact. Vaccination helps prevent the disease yields four phenotypic categories. The ratio arises from
by enabling the body to develop specific antibodies. the independent segregation of alleles governing two
Gonorrhea, syphilis, and chlamydia are bacterial separate traits. The classic 9:3:3:1 distribution highlights
infections not prevented by the hepatitis B vaccine. how each trait’s inheritance pattern does not affect the
other, reflecting Mendelian principles.
9. Which procedure involves directly flushing out an
embryo from a genetically superior female animal to 12. Match the following terms in Column I with their
transfer it into another female? genetic descriptions in Column II:
(A) ZIFT
(B) GIFT Column I Column II
(C) MOET 1. Haemophilia a. XO chromosomal
(D) ICSI constitution

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page 98 CUET UG Biology

2. Turner’s syndrome b. Recessive X-linked (D) Polygenic inheritance

disorder

Ans
3. Sickle-cell anemia c. XXY chromosomal (C) Linkage
constitution Linked genes are located close together on the same
4. Klinefelter’s d. Caused by a point chromosome, making them tend to be inherited
syndrome mutation in β-globin together. They do not follow the 9:3:3:1 ratio seen with
gene unlinked genes. Although crossing over can separate
Options: linked genes, proximity often reduces crossover
(A) 1-b, 2-a, 3-d, 4-c frequency. Thus, linkage significantly alters standard
(B) 1-d, 2-c, 3-b, 4-a independent assortment ratios.
(C) 1-b, 2-c, 3-d, 4-a
15. Which element is crucial for forming the transcription
(D) 1-c, 2-b, 3-a, 4-d
initiation complex in prokaryotes?


Ans (A) 5’ cap
(A) 1-b, 2-a, 3-d, 4-c (B) Promoter region
Haemophilia (b) is an X-linked recessive disorder. (C) Poly-A tail
Turner’s syndrome (a) involves a single X chromosome (D) Ribosomal subunit
(XO). Sickle-cell anemia (d) arises from a point mutation

Ans
in the β-globin gene. Klinefelter’s syndrome (c) features
(B) Promoter region
an XXY constitution. This matching demonstrates
In prokaryotes, RNA polymerase and associated
classic patterns of chromosomal and gene-based
factors bind to the promoter sequence upstream of
abnormalities.
the structural gene to initiate transcription. The 5’ cap
13. Identify the correct set of statements about multiple and poly-A tail are eukaryotic mRNA modifications,
allelism using the ABO blood group as an example: while ribosomal subunits are central to translation, not
1. More than two alleles exist for a single gene. transcription. The promoter is essential for correct gene
2. Each individual carries all existing alleles in their expression.
cells.
16. Which is NOT a function of the lac operon repressor?
3. IA and IB show codominance.
(A) Binding to the operator region
4. i is recessive to both IA and IB.
(B) Undergoing inactivation in presence of an inducer
5. Every person inherits three different alleles.
(C) Directly synthesizing β-galactosidase
Options:
(D) Blocking RNA polymerase access to structural
(A) 1, 2, 3
genes
(B) 1, 3, 4
(C) 2, 4, 5

Ans
(D) 1, 3, 5 (C) Directly synthesizing β-galactosidase


Ans The lac repressor binds to the operator, preventing
RNA polymerase from transcribing the lac genes. In
(B) 1, 3, 4
lactose presence, the inducer (allolactose) inactivates
ABO blood groups illustrate multiple allelism because
the repressor. The repressor does not produce
more than two alleles (IA, IB, i) exist. IA and IB are
β-galactosidase; that enzyme is encoded by lacZ. Hence,
codominant, and i is recessive to both. However, an
synthesizing β-galactosidase is not a repressor function
individual can only have two alleles, not all of them
but a structural gene product.
simultaneously. Thus, statements 1, 3, and 4 are correct
here. 17. Which region of a eukaryotic gene is removed during
RNA processing to produce mature mRNA?
14. Which phenomenon explains why linked genes do not
(A) Exons
exhibit typical Mendelian independent assortment?
(B) Introns
(A) Mutation
(C) Promoter
(B) Crossing over
(D) Terminator
(C) Linkage

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Ans (B) Plasmodium vivax

(B) Introns (C) Giardia intestinalis
Eukaryotic pre-mRNA contains exons (coding regions) (D) Leishmania donovani
interspersed with introns (non-coding). Splicing

Ans
removes introns, joining exons to form the mature
(B) Plasmodium vivax
mRNA that will be translated. The promoter and
Malaria is primarily caused by Plasmodium species,
terminator function in transcription regulation but are
including P. vivax, P. falciparum, P. malariae, and P.
not retained in the final coding transcript. Thus, introns
ovale. P. vivax is widespread and responsible for many
are spliced out during RNA processing.
cases. Entamoeba histolytica causes amoebiasis, Giardia
18. Assertion (A) : A high mutation rate can rapidly alter intestinalis causes giardiasis, and Leishmania donovani
allele frequencies in a small population. causes kala-azar. Thus, Plasmodium vivax stands as a
Reason (R) : Mutations always confer a survival key malarial pathogen.
advantage.
21. Which pathogen primarily targets the liver during its
(A) Both Assertion and Reason are true, and Reason is
life cycle, causing jaundice-like symptoms?
the correct explanation.
(A) Human immunodeficiency virus
(B) Both Assertion and Reason are true, but Reason is
(B) Mycobacterium tuberculosis
not the correct explanation.
(C) Salmonella typhi
(C) Assertion is true, but Reason is false.
(D) Hepatitis virus
(D) Assertion is false, but Reason is true.


Ans


Ans
(D) Hepatitis virus
(C) Assertion is true, but Reason is false.
Hepatitis viruses (A, B, C, D, E) mainly infect liver cells,
Mutations in small populations can significantly change
often leading to jaundice-like symptoms due to bilirubin
allele frequencies, especially if the population is already
buildup. HIV attacks immune cells, TB bacteria infect
genetically limited. However, mutations are random and
the lungs primarily, and Salmonella typhi leads to
do not always provide a survival advantage. Many are
typhoid fever. Hence, hepatitis viruses specifically affect
neutral or deleterious. Therefore, while the assertion
liver function and can cause hepatitis.
stands, the reason incorrectly generalizes mutation
effects on fitness. 22. Which is NOT part of the body’s innate immune
defenses?
19. Which selection mode occurs when both extreme
(A) Skin barrier
phenotypes are favored over the intermediate
(B) Phagocytic white blood cells
phenotype?
(C) Memory B cells
(A) Stabilizing selection
(D) Natural killer cells
(B) Directional selection
(C) Disruptive selection

Ans
(D) Artificial selection (C) Memory B cells


Ans Innate immunity refers to non-specific defenses present
from birth, such as skin, phagocytes, and natural killer
(C) Disruptive selection
cells. Memory B cells belong to adaptive immunity,
Disruptive (or diversifying) selection drives a
recognizing specific antigens from previous exposures
population toward two or more distinct phenotypic
and mounting targeted responses. Hence, memory
forms by favoring individuals at both extremes. This can
B cells are not part of innate defense but central to
eventually lead to speciation if subpopulations occupy
acquired immunity.
different ecological niches. Stabilizing selection favors
intermediates, while directional selection pushes the 23. Which term describes the intentional misuse of a
phenotype toward one extreme. Artificial selection is substance that alters bodily functions, causing physical
human-driven. or psychological dependence?
(A) Immunization
20. Which protozoan causes malaria in humans?
(B) Drug abuse
(A) Entamoeba histolytica
(C) Inflammation

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(D) Allergen response (A) DNA ligase

Ans (B) RNA primase
(C) DNA gyrase
(B) Drug abuse (D) Reverse transcriptase
Drug abuse is the self-administration of drugs to alter
mood, perception, or consciousness in ways harmful

Ans
to the individual and society. It includes physical and (A) DNA ligase
psychological dependence. Immunization boosts DNA ligase forms phosphodiester bonds between
immunity, inflammation is a tissue response to injury, adjacent nucleotides, joining Okazaki fragments
and allergen response involves hypersensitivity, distinct during replication and sealing DNA fragments in
from the voluntary misuse in drug abuse. recombinant technology. RNA primase synthesizes
RNA primers, DNA gyrase relieves supercoiling, and
24. Which disease is closely linked with chronic high-risk reverse transcriptase synthesizes cDNA from RNA.
behaviors and significant immune system compromise? Ligase’s binding action is essential for stable plasmid
(A) Typhoid construction.
(B) AIDS
(C) Amoebiasis 27. What is the primary advantage of using PCR (Polymerase
(D) Ringworm Chain Reaction) in DNA analysis?


Ans (A) It digests proteins rapidly
(B) It replicates only mRNA
(B) AIDS (C) It amplifies specific DNA sequences exponentially
Acquired Immunodeficiency Syndrome (AIDS) results (D) It prevents DNA polymerase from functioning
from HIV infection that heavily compromises the
immune system. Unprotected sex, sharing contaminated

Ans
needles, and other high-risk behaviors facilitate (C) It amplifies specific DNA sequences exponentially
transmission. Typhoid, amoebiasis, and ringworm PCR targets a specific DNA region and uses repeated
occur differently, lacking the hallmark immune collapse cycles of denaturation, annealing of primers, and
and direct linkage to such specific high-risk behavioral extension to produce millions of copies. This is central to
factors as HIV/AIDS does. diagnostics, forensics, and research. PCR does not digest
proteins, nor does it halt DNA polymerase function. It
25. Assertion (A) : Restriction enzymes are crucial for instead exploits polymerases for DNA amplification.
recombinant DNA technology.
Reason (R) : They degrade mRNA molecules before 28. Which of the following is NOT typically considered a
translation. concern associated with genetically modified organisms
(A) Both Assertion and Reason are true, and Reason is (GMOs)?
the correct explanation. (A) Development of pest-resistant strains
(B) Both Assertion and Reason are true, but Reason is (B) Increase in biodiversity
not the correct explanation. (C) Potential allergenicity in some consumers
(C) Assertion is true, but Reason is false. (D) Horizontal gene transfer to wild relatives
(D) Assertion is false, but Reason is true.

Ans


Ans (B) Increase in biodiversity
(C) Assertion is true, but Reason is false. Common concerns include pests evolving resistance,
Restriction enzymes act like molecular scissors, unexpected allergic reactions, and gene flow to wild
recognizing and cutting specific DNA sequences, relatives. GMOs often focus on specific traits, potentially
making them vital for gene manipulation. However, narrowing genetic diversity. An overall increase in
they do not target mRNA nor degrade it. Their role is biodiversity is not a typical worry; in many scenarios,
strictly in cutting DNA, enabling insertion or removal reliance on fewer genetically uniform varieties can
of fragments. Hence, the reason is incorrect for this reduce diversity.
context.
29. Which term describes inserting a healthy gene into a
26. Which molecule is employed to seal DNA fragments patient’s cells to correct a faulty gene?
together after restriction digestion? (A) Somatic hybridization

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 PRACTICE PAPER 10

(B) Gene therapy (D) Ecological efficiency

(C) Eugenics

Ans
(D) Biopiracy
(A) Gross primary productivity


Ans Gross primary productivity (GPP) represents the total
(B) Gene therapy rate at which energy is captured by producers through
Gene therapy involves introducing a normal gene into photosynthesis. Some fraction is used in respiration.
cells with defective or missing counterparts, aiming Net primary productivity (NPP) equals GPP minus
to restore normal function. Somatic hybridization respiratory losses, and secondary productivity reflects
merges different cells, eugenics refers to altering biomass generation in consumers. Ecological efficiency
human populations genetically via selective breeding, is the ratio of energy passed between trophic levels.
and biopiracy involves exploiting biological resources
33. Arrange the following processes to illustrate the flow
without proper authorization. Gene therapy thus
directly addresses genetic disorders. of energy in an aquatic ecosystem, beginning with
sunlight:
30. Which interaction involves one species benefitting by 1. Phytoplankton photosynthesis
feeding on another that is harmed in the process? 2. Fish consuming zooplankton
(A) Mutualism 3. Zooplankton feeding on phytoplankton
(B) Predation 4. Apex predators feeding on fish
(C) Commensalism Options:
(D) Competition (A) 2 → 3 → 1 → 4


Ans (B) 1 → 3 → 2 → 4
(C) 3 → 1 → 4 → 2
(B) Predation (D) 4 → 2 → 1 → 3
Predation is an interspecific interaction where one
organism, the predator, kills and consumes another,

Ans
the prey. Mutualism benefits both organisms, (B) 1 → 3 → 2 → 4
commensalism benefits one without harming the other, Sunlight drives phytoplankton photosynthesis (1).
and competition negatively impacts both because they Zooplankton then consume phytoplankton (3). Fish feed
vie for the same resources. Predation distinctly involves on zooplankton (2), and apex predators ultimately feed
direct harm to the prey. on fish (4). This sequence captures the typical aquatic
food chain, showcasing successive energy transfers
31. Which factor primarily limits the number of trophic among trophic levels until reaching top predators.
levels in an ecosystem?
(A) Abundance of decomposers 34. Which region typically exhibits the highest species
(B) 10% energy transfer law diversity?
(C) Oxygen concentration (A) Polar sea
(D) Presence of apex predators (B) Alpine tundra


Ans (C) Tropical rainforest
(D) Desert grassland
(B) 10% energy transfer law
According to the 10% law, only about 10% of energy

Ans
is transferred to the next trophic level. This substantial (C) Tropical rainforest
energy loss at each transfer restricts how many levels Tropical rainforests, located around the equator, have
can be supported. Decomposers, oxygen availability, abundant sunlight, stable climates, and high rainfall,
and apex predators matter ecologically, but the energy fostering diverse niches. This leads to extremely rich
loss fundamentally caps trophic chain length. biodiversity. Polar seas, alpine tundra, and deserts
generally host fewer species due to harsher conditions,
32. Which term denotes the total biomass produced by limited resources, and extreme seasonal variations that
autotrophs in an ecosystem per unit time? reduce overall species richness.
(A) Gross primary productivity
(B) Net primary productivity 35. Which group of microorganisms is primarily responsible
(C) Secondary productivity for energy generation in biogas plants?

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(A) Viruses

Ans

(B) Methanogenic archaea (B) SCID (Severe Combined Immunodeficiency)
(C) Protozoa SCID affects both B and T lymphocyte functions,
(D) Photosynthetic algae leaving the sufferer prone to multiple infections. Colour


Ans blindness relates to X-linked recessive vision deficiency,
while Down’s syndrome and Turner’s syndrome are
(B) Methanogenic archaea
chromosomal anomalies. SCID directly compromises
Methanogenic archaea degrade organic matter
immunity, showing how genetic errors can cause severe
anaerobically to produce methane, a key component of
immunological weakness.
biogas. These microbes thrive in oxygen-free conditions
such as biogas digesters. Viruses lack metabolic 38. Select the set of correct statements regarding the
processes, protozoa consume other organisms, significance of seeds and fruits:
and photosynthetic algae require sunlight, making 1. Seeds protect the embryo from desiccation
methanogens the principal players in biogas production 2. Fruits aid in the forced self-pollination of plants
systems. 3. Many fruits facilitate dispersal by animals
4. Viability of seeds is independent of external
36. Match the following microbial products in Column I
conditions
with their applications in Column II:
5. Some seeds can remain dormant until favorable
Column I Column II conditions arise
1. Penicillium a. Ethanol fermentation Options:
notatum (A) 1, 3, and 5
2. Saccharomyces b. Butanol and acetone (B) 2, 3, and 4
cerevisiae production (C) 1, 2, and 4
(D) 3, 4, and 5
3. Clostridium c. Antibiotic penicillin
acetobutylicum production

Ans
4. Lactobacillus d. Curd formation and (A) 1, 3, and 5
acidophilus probiotic use Seeds protect the embryo from harsh environments
Options: (1). Fruits often attract animals that disperse seeds (3).
(A) 1-c, 2-a, 3-b, 4-d Seeds can remain dormant until conditions improve (5).
(B) 1-d, 2-c, 3-a, 4-b Statement 2 is incorrect because fruits generally promote
(C) 1-c, 2-b, 3-a, 4-d dispersal, not forced self-pollination. Statement 4 is
(D) 1-a, 2-d, 3-b, 4-c incorrect as seed viability depends on suitable external
factors.


Ans
39. Assertion (A) : A reduction in biodiversity hotspots can
(A) 1-c, 2-a, 3-b, 4-d
Penicillium notatum (c) produces penicillin. severely impact global ecosystem stability.
Saccharomyces cerevisiae (a) drives ethanol Reason (R) : Hotspots contain numerous endemic
fermentation. Clostridium acetobutylicum (b) generates species vulnerable to habitat loss.
solvents like butanol and acetone. Lactobacillus (A) Both Assertion and Reason are true, and Reason is
acidophilus (d) aids curd formation and serves as a the correct explanation.
probiotic bacterium. This matching highlights diverse (B) Both Assertion and Reason are true, but Reason is
microbial roles in human welfare. not the correct explanation.
(C) Assertion is true, but Reason is false.
37. Which hereditary disorder involves defects in the (D) Assertion is false, but Reason is true.
immune system, often resulting in severe, recurrent

Ans
infections?
(A) Colour blindness (A) Both Assertion and Reason are true, and Reason is
(B) SCID (Severe Combined Immunodeficiency) the correct explanation.
(C) Down’s syndrome Biodiversity hotspots have high endemism, so habitat
(D) Turner’s syndrome degradation there leads to rapid biodiversity losses
with serious ecological repercussions. Because endemic

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 PRACTICE PAPER 10

species often cannot survive outside their native range, In the scenario, the counselor cites karyotyping as a
losing these regions undermines ecosystem resilience. modern tool for assessing chromosomes. Karyotyping
Thus, the reason directly elucidates how hotspot visualizes the size, number, and structure of
destruction destabilizes global ecological balance. chromosomes, helping detect anomalies like Down’s
syndrome. Hemoglobin electrophoresis checks for
40. Which approach helps preserve biodiversity in its abnormal hemoglobin, PCR amplifies DNA regions, and
natural habitat? ELISA is for antigen-antibody detection. Karyotyping
(A) In situ conservation pinpoints chromosomal issues directly.
(B) Ex situ conservation
(C) Monoculture farming 42. Which inheritance pattern might Vaibhav’s aunt have,
(D) Cloning all species in laboratories as suggested by her symptoms?


Ans (A) Autosomal dominant
(B) Sex-linked recessive
(A) In situ conservation (C) Autosomal codominant
In situ conservation preserves species within their (D) Mitochondrial inheritance
native habitats, maintaining ecological integrity.
National parks, wildlife sanctuaries, and biosphere

Ans
reserves exemplify this. Ex situ conservation (zoos, seed (B) Sex-linked recessive
banks) removes organisms from their surroundings. The counselor references an X-linked recessive
Monoculture farming reduces diversity, while cloning all condition, meaning the defective gene resides on the
species in labs is neither practical nor wholly protective. X chromosome. Females typically need two mutated
copies to express the disorder fully, whereas males with


Direction :Carefully read the case study provided and then one affected X show symptoms. Autosomal dominant or
thoroughly answer the subsequent five questions. codominant patterns differ in inheritance routes, and
Vaibhav, a Class 12 student, visited a local hospital’s genetic mitochondrial genes pass maternally.
counseling unit, where his aunt was undergoing tests for
suspected genetic disorders. The counselor discussed 43. Which technique is mentioned for prenatal screening
Mendelian patterns and chromosomal anomalies, alongside amniocentesis in the discussion?
highlighting how modern techniques like karyotyping (A) Endoscopy
and DNA fingerprinting aid accurate diagnosis. Vaibhav (B) Magnetic Resonance Imaging (MRI)
learned about autosomal dominant, autosomal recessive, (C) Chorionic villus sampling (CVS)
and sex-linked disorders, recognizing the significance (D) Laparoscopy
of pedigree analysis in tracing inheritance. His aunt’s

Ans
symptoms suggested a possibility of an X-linked recessive
condition. Despite concerns, the counselor explained (C) Chorionic villus sampling (CVS)
that early interventions and supportive therapies could The case highlights both amniocentesis and chorionic
mitigate complications. Intrigued, Vaibhav asked villus sampling for detecting genetic abnormalities in
about the importance of prenatal screening, and the fetuses. CVS involves sampling placental tissue, which
counselor mentioned amniocentesis and CVS, stressing carries fetal cells. MRI and endoscopy have different
ethical guidelines. This experience broadened Vaibhav’s medical uses, and laparoscopy is minimally invasive
perspective on genetics, emphasizing informed decision- surgery. Thus, CVS parallels amniocentesis as a key
making and the value of scientific advancements overall. prenatal diagnostic test.

44. How does pedigree analysis assist families suspecting

41. Which diagnostic technique is specifically mentioned
for analyzing an individual’s chromosomal makeup? genetic disorders?
(A) Hemoglobin electrophoresis (A) It definitively cures genetic diseases
(B) Karyotyping (B) It completely prevents mutation accumulation
(C) PCR-based gene amplification (C) It traces inheritance patterns across generations
(D) Enzyme-linked immunosorbent assay (D) It replaces the need for all diagnostic tests

Ans

Ans

(B) Karyotyping (C) It traces inheritance patterns across generations

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Pedigree charts document family histories, displaying (A) Steady bird population growth despite warming
how a trait or disorder is transmitted. While they cannot (B) Flourishing fish populations outcompeting
cure diseases or stop new mutations, they help identify predators
carriers, predict risk, and guide decisions. Diagnostic (C) Decline in certain fish species essential for
tests might still be necessary for confirmation. Hence, predatory birds
pedigrees primarily illuminate generational inheritance (D) Uniform water levels maintained year-round
patterns.

Ans
45. Which statement captures the counselor’s ethical (C) Decline in certain fish species essential for predatory
emphasis regarding prenatal diagnosis? birds
(A) Testing must be done randomly on all pregnant Dr. Sharma observes fewer fish species that once
women without consent supported predatory bird populations. When a key
(B) Results should never be disclosed to families food source diminishes, top predators also decline or
(C) Ethical guidelines ensure informed choices and migrate. Steady bird growth or uniform water levels
respect for privacy would suggest stability. Flourishing fish populations
(D) Genetic tests are mandated by law for every would not indicate disruption. Hence, reduced fish
newborn signals ecological imbalance.


Ans 47. Why are migratory bird numbers decreasing according
(C) Ethical guidelines ensure informed choices and to the case?
respect for privacy (A) Unchanged breeding habitats that provide stable
The counselor highlights the importance of adhering nesting
to ethical standards in prenatal screening, meaning (B) Excessive competition from invasive ducks
informed consent, confidentiality, and respectful (C) Altered breeding habitats linked to higher
communication of results. Mandating tests by law, temperatures
testing without consent, or withholding information (D) Complete immunity to temperature variations
entirely violates ethical principles. Thus, the central

Ans
message is about respecting patient autonomy and
confidentiality. (C) Altered breeding habitats linked to higher
temperatures


Direction :Carefully read the case study provided and then The scenario points to climate-induced changes in
thoroughly answer the subsequent five questions. the wetland environment. Rising temperatures affect
Dr. Sharma is researching the impact of climate change aquatic plant growth and water availability, altering
on a local wetland ecosystem. He notices that water the conditions migratory birds rely on. No mention is
temperatures have risen steadily over the past decade, made of invasive ducks, and “unchanged habitats” or
coinciding with shifts in aquatic plant growth and insect “complete immunity” contradict the observed shifts.
populations. Migratory bird species, once thriving, now Hence, habitat alteration causes fewer bird arrivals.
arrive in smaller numbers due to altered breeding habitats.
The wetland’s food chains show signs of imbalance, 48. Which factor contributes to pollutant concentration in
as certain fish species have declined, reducing food the wetland ecosystem?
availability for predatory birds. Increased evaporation is (A) Rapid infiltration of fresh water
also lowering water levels, concentrating pollutants. Dr. (B) Frequent heavy rainfall
Sharma collaborates with conservationists to introduce (C) Lower water levels due to evaporation
native plant species that withstand higher temperatures, (D) Overgrowth of aquatic plants filtering toxins
hoping to stabilize the ecosystem. Community awareness

Ans
programs emphasize curbing pollution, sustainable water (C) Lower water levels due to evaporation
usage, and mitigating climate impacts. His findings The case notes that increased evaporation lowers
underscore the delicate interdependence among wetland water volume, concentrating existing pollutants in a
organisms overall. smaller area. Rapid influxes of fresh water would dilute
46. Which direct observation suggests a disrupted ecological pollutants, while frequent heavy rainfall could also
balance in Dr. Sharma’s wetland study? dilute or flush them out. Aquatic plant overgrowth might

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 PRACTICE PAPER 10

actually absorb some contaminants. Thus, evaporation

heightens pollutant concentration.

49. What is one mitigation strategy Dr. Sharma pursues to

stabilize the ecosystem?
(A) Complete drainage of the wetland
(B) Introduction of native plants tolerant to higher
temperatures
(C) Intensive pesticide usage to kill pests
(D) Banning all fishing activities immediately


Ans
(B) Introduction of native plants tolerant to higher
temperatures
The passage states that Dr. Sharma collaborates with
conservationists to introduce resilient local plant
species. This measure helps maintain habitat structure,
absorb pollutants, and offer shelter for aquatic life
under warmer conditions. Draining the wetland, using
excessive pesticides, or banning all fishing are not
mentioned or recommended solutions here.

50. Which broader message does Dr. Sharma’s research

highlight about wetlands?
(A) They function independently from climatic
variations
(B) Organisms remain unaffected by minor temperature
shifts
(C) Wetlands showcase interconnected food webs
sensitive to environmental change
(D) Conservation efforts are futile because nature self-
corrects unconditionally


Ans
(C) Wetlands showcase interconnected food webs
sensitive to environmental change
The case underscores how temperature rise and
evaporation disrupt multiple trophic levels, impacting
fish, insects, and migratory birds. This interdependence
forms the wetland’s complex food web, vulnerable
to climate shifts. Claiming wetlands function
independently, organisms remain unaffected, or that
conservation is pointless contradicts the documented
fragility described.

*************

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PRACTICE PAPER 11

1. Which cell of a mature pollen grain eventually grows Apomixis is a reproductive process where seeds
into the pollen tube? form without the fusion of male and female gametes,
(A) Exine cell bypassing typical fertilization. In citrus, certain
(B) Vegetative cell nucellar cells can develop into embryos, leading to
(C) Generative cell seed formation genetically identical to the parent.
(D) Intine cell This preserves desirable traits but significantly reduces


Ans overall genetic variability in offspring populations.

(B) Vegetative cell 4. Which of the following is NOT a function of the Sertoli
The vegetative cell, called the tube cell, initiates growth cells in the testis?
of the pollen tube after pollination. This tube travels (A) Providing nutrition to developing sperm
through the style to carry the sperm nuclei produced (B) Facilitating sperm release into the lumen
by the generative cell. Exine and intine refer to pollen (C) Secreting testosterone
wall layers, which do not form the tube, highlighting the (D) Forming the blood-testis barrier
vegetative cell’s role.

Ans
2. Why does pollen-pistil interaction help prevent self- (C) Secreting testosterone
pollination in many flowering plants? Leydig cells secrete testosterone, not Sertoli cells. Sertoli
(A) It allows pollinators to sense flower color changes cells nourish developing sperm, regulate their release
(B) It identifies incompatible pollen and inhibits into seminiferous tubules, and maintain the blood-testis
germination barrier. They also produce certain signaling molecules
(C) It accelerates double fertilization but do not produce testosterone. Thus, secretion of
(D) It ensures more nectar production testosterone is most distinctly carried out by interstitial


Ans (Leydig) cells in the testis.

(B) It identifies incompatible pollen and inhibits 5. Which event marks the transition from follicular phase
germination to luteal phase in the human menstrual cycle?
Pollen-pistil interaction involves molecular recognition (A) Menstruation
between stigma and pollen. If pollen is genetically (B) Ovulation
similar or incompatible, the pistil signals prevent (C) Implantation
tube formation or growth, effectively blocking self- (D) Endometrial thickening
pollination. This mechanism promotes genetic diversity

Ans
by favoring cross-pollination, helping plants avoid
potentially deleterious inbreeding effects and maintain (B) Ovulation
healthier, more robust, and stable offspring. Ovulation is triggered by a surge in luteinizing hormone,
releasing the secondary oocyte from the mature Graafian
3. Which term refers to producing seeds without follicle. After this, the remnant follicle transforms
fertilization, as sometimes seen in citrus plants? into the corpus luteum, marking the start of the luteal
(A) Parthenogenesis phase. This shift is crucial for possible implantation and
(B) Apomixis maintenance of early pregnancy if fertilization occurs.
(C) Polyembryony
6. Assertion (A) : Fertilization in humans typically occurs
(D) Parthenocarpy
in the fallopian tube.


Ans Reason (R) : The ovum remains viable in the uterus for
(B) Apomixis several days awaiting sperm.

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 PRACTICE PAPER 11

(A) Both Assertion and Reason are true, and Reason is regulate hormones to prevent ovulation. Thus, options 1
the correct explanation. and 2 are barriers, 3 is IUD, 4 is oral contraception.
(B) Both Assertion and Reason are true, but Reason is
9. Why is medical termination of pregnancy (MTP)
not the correct explanation.
(C) Assertion is true, but Reason is false. recommended to be performed during the first
(D) Assertion is false, but Reason is true. trimester?
(A) Less hormonal influence


Ans (B) High fetal movement
(C) Assertion is true, but Reason is false (C) Lower risk of complications
Human fertilization usually happens in the ampullary (D) Enhanced organogenesis
region of the fallopian tube shortly after ovulation. The

Ans
released ovum is viable for about 24 hours in the tube,
not the uterus, awaiting sperm entry. Thus, while the (C) Lower risk of complications
assertion is correct, the reason provided is inaccurate The first trimester is generally considered safer for MTP
regarding ovum viability location and duration. because the fetus is less developed, and the procedure
is simpler, with reduced surgical or pharmacological
7. Which procedure involves inserting a small amount complications. As pregnancy advances, maternal and
of amniotic fluid into a test tube to screen for genetic fetal risks increase. Therefore, performing MTP earlier
abnormalities? lowers potential health hazards for both the pregnant
(A) IVF individual and the fetus.
(B) Amniocentesis
10. Match the following genetic terms with their
(C) ZIFT
(D) GIFT descriptions:

Ans Column I Column II

(B) Amniocentesis 1. Pleiotropy A. Multiple alleles contribute
Amniocentesis is a prenatal diagnostic technique that to a single phenotype
collects amniotic fluid, containing fetal cells, via a 2. Codominance B. Both alleles express equally
needle inserted into the amniotic sac. These cells are in heterozygote
then analyzed for chromosomal or genetic disorders. 3. Incomplete C. One gene influences
Although valuable for early detection, misuse for dominance multiple traits
sex determination can lead to ethical issues, so its 4. Polygenic D. Heterozygote shows
application is regulated. inheritance intermediate phenotype
8. Which combination of birth control methods is correct Options:
regarding barrier methods and intrauterine devices? (A) 1-C, 2-B, 3-D, 4-A
1. Condom (B) 1-D, 2-A, 3-B, 4-C
2. Diaphragm (C) 1-B, 2-D, 3-C, 4-A
3. Copper T (D) 1-A, 2-D, 3-C, 4-B
4. Oral Pill

Ans
(A) 1,2 are IUDs; 3,4 are barriers
(A) 1-C, 2-B, 3-D, 4-A
(B) 1,3 are barriers; 2,4 are IUDs
Pleiotropy (1) describes a single gene affecting several
(C) 1,2 are barriers; 3 is an IUD; 4 is oral contraception
traits (C). Codominance (2) involves both alleles fully
(D) 2,3 are barriers; 1,4 are IUDs
expressing in heterozygotes (B). Incomplete dominance


Ans (3) shows an intermediate phenotype in heterozygotes
(C) 1,2 are barriers; 3 is an IUD; 4 is oral contraception (D). Polygenic inheritance (4) arises from multiple
Condoms and diaphragms are barrier methods genes or alleles contributing to a single characteristic
preventing sperm from reaching the egg. Copper T, an (A), truly demonstrating complex genetic patterns.
intrauterine device, is placed in the uterus to hinder
11. Which term describes different forms of a gene located
fertilization or implantation. These oral pills effectively
at the same locus on homologous chromosomes?
(A) Alleles

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(B) Linkage groups 3. Initiation codon recognized

(C) Chromatids 4. Peptide bond formation
(D) Mutons 5. Translocation


Ans Options:
(A) 3-1-2-4-5
(A) Alleles (B) 1-3-2-5-4
Alleles are alternate versions of a gene at the same (C) 1-2-3-4-5
genetic locus on homologous chromosomes. They code (D) 3-2-1-4-5
for variations in the same trait, such as flower color. An
individual inherits one allele from each parent. Different

Ans
allele combinations can produce different phenotypes, (A) 3-1-2-4-5
forming the basis for genetic diversity and inheritance. First, the initiation codon on mRNA is recognized, then
mRNA attaches to the ribosome. Next, the appropriate
12. Why does incomplete dominance in snapdragons aminoacyl-tRNA binds, allowing peptide bond
produce a pink phenotype in heterozygotes? formation. Finally, ribosomal translocation moves the
(A) One allele is completely suppressed ribosome along mRNA. This sequence ensures correct
(B) Both alleles are equally expressed polypeptide assembly, strictly reflecting the orderly
(C) The dominant allele is only partially expressed steps required in translation’s initiation, elongation, and
(D) The recessive allele outcompetes the dominant termination phases.
allele
15. Which enzyme catalyzes the unwinding of the DNA


Ans
double helix during replication?
(C) The dominant allele is only partially expressed (A) DNA polymerase
In incomplete dominance, a dominant allele (B) DNA helicase
cannot fully mask the recessive one, resulting in (C) DNA ligase
an intermediate phenotype. In snapdragons, red (D) Topoisomerase
(dominant) allele expression is diluted, producing a
pink color in heterozygotes. Neither allele achieves

Ans
complete phenotypic dominance, truly illustrating how (B) DNA helicase
partial expression leads to a blended appearance in the DNA helicase unwinds the double helix by breaking
offspring. hydrogen bonds between complementary bases, creating
two single-stranded templates. DNA polymerase then
13. Which is NOT a Mendelian disorder? synthesizes new strands using these templates. DNA
(A) Sickle cell anemia ligase joins Okazaki fragments, while topoisomerase
(B) Hemophilia relieves supercoiling tension. Helicase’s role is highly
(C) Down’s syndrome crucial for the replication fork to progress efficiently
(D) Thalassemia along DNA.


Ans
16. What is the function of the anticodon loop in tRNA?
(C) Down’s syndrome (A) It forms a polypeptide chain
Mendelian disorders, like sickle cell anemia, hemophilia, (B) It recognizes mRNA codons
and thalassemia, typically result from mutations in (C) It splices introns from mRNA
single genes. By contrast, Down’s syndrome arises from (D) It binds ribosomal subunits together
a chromosomal abnormality (trisomy 21) rather than
a single-gene mutation. This extra chromosome leads

Ans
to distinct clinical features, quite significantly further (B) It recognizes mRNA codons
distinguishing it from classic Mendelian inheritance The tRNA anticodon loop contains three nucleotides
patterns. complementary to the mRNA codon, ensuring the
correct amino acid is incorporated into the growing
14. Arrange the following events of protein synthesis in polypeptide. This specificity underlies the fidelity of
correct chronological order: translation, linking each codon to its corresponding
1. mRNA attaches to ribosome
2. Aminoacyl-tRNA binds

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 PRACTICE PAPER 11

amino acid. Introns are spliced from pre-mRNA, and 2. Natural selection
ribosomal subunits bind independently of tRNA. 3. Polyembryony
4. Genetic drift
17. Match the following with their primary role in gene 5. Parthenogenesis
regulation: Options:
Column I Column II (A) 1, 2, and 4
1. Promoter A. Binds to operator to inhibit (B) 2, 3, and 5
transcription (C) 1, 4, and 5
(D) 1, 3, and 5
2. Repressor B. Segment of DNA recognized by
RNA polymerase

Ans
3. Operator C. Region where repressor binds (A) 1, 2, and 4
4. Inducer D. Molecule that inactivates Modern synthetic theory emphasizes gene mutations
repressor as the source of variation, natural selection as the
directional force filtering these variations, and
Options:
genetic drift as random fluctuations influencing allele
(A) 1-A, 2-B, 3-C, 4-D
frequencies. Polyembryony and parthenogenesis
(B) 1-B, 2-A, 3-C, 4-D
involve specific reproductive phenomena, but they do
(C) 1-C, 2-D, 3-B, 4-A
not universally shape population-level evolutionary
(D) 1-D, 2-C, 3-A, 4-B
change as strongly as those three factors.


Ans
20. Why does the Hardy-Weinberg principle require a large
(B) 1-B, 2-A, 3-C, 4-D
population size?
A promoter (1) is a DNA region recognized by RNA
(A) Large populations mutate slower
polymerase (B). A repressor (2) binds to the operator,
(B) Random mating cannot happen in small groups
blocking transcription (A). The operator (3) is the DNA
(C) Sampling error is minimized in large populations
segment where the repressor attaches (C). An inducer
(D) Allele frequencies do not exist in small populations
(4) inactivates the repressor, thus enabling expression
(D) and promoting required genes when needed.

Ans
(C) Sampling error is minimized in large populations
18. Which statement differentiates natural selection from
The Hardy-Weinberg principle assumes large population
genetic drift?
size to minimize fluctuations in allele frequencies that
(A) Only genetic drift increases genetic variation
could distort equilibrium. Smaller populations are
(B) Genetic drift is caused by selective pressures
prone to genetic drift, causing greater deviations from
(C) Natural selection is non-random, while genetic
predicted proportions. By reducing sampling errors,
drift is random
a large population ensures that allele and genotype
(D) Natural selection never affects large populations
frequencies remain stable if other conditions are met.


Ans
21. Which preventive measure best reduces vector-borne
(C) Natural selection is non-random, while genetic drift
infections like malaria and dengue?
is random
(A) Drinking boiled water
Natural selection favors individuals with advantageous
(B) Using bed nets and eliminating stagnant water
traits, truly a non-random process driven by
(C) Consuming vitamin supplements
environmental pressures. Genetic drift involves random
(D) Undergoing regular blood tests
fluctuations in allele frequencies due to chance events,
especially in small populations. Selection systematically

Ans
shapes adaptation, while drift may increase or decrease (B) Using bed nets and eliminating stagnant water
certain alleles unpredictably, independent of trait Malaria and dengue are transmitted by mosquitoes
benefits or disadvantages. breeding in standing water. Removing stagnant water
sources and using mosquito nets or repellents disrupts
19. Which set of factors primarily drives evolution
the insects’ life cycle and reduces contact with humans.
according to modern synthetic theory?
Boiled water prevents waterborne diseases; vitamins
1. Gene mutation

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bolster health but not specifically against mosquito (A) 1-D, 2-C, 3-A, 4-B
transmission, and blood tests detect infection. (B) 1-C, 2-D, 3-A, 4-B
(C) 1-B, 2-C, 3-D, 4-A
22. Assertion (A) : AIDS results from infection by HIV, a (D) 1-A, 2-B, 3-C, 4-D
retrovirus.
Reason (R) : Retroviruses do not integrate their genetic

Ans
material into the host genome. (A) 1-D, 2-C, 3-A, 4-B
(A) Both Assertion and Reason are true, and Reason is Saccharomyces cerevisiae (1) is the common yeast used
the correct explanation. in baking and brewing (D). Penicillium notatum (2)
(B) Both Assertion and Reason are true, but Reason is produces the antibiotic penicillin (C). Methanobacterium
not the correct explanation. (3) helps produce biogas (A) by breaking down organic
(C) Assertion is true, but Reason is false. matter anaerobically. Lactobacillus (4) ferments lactose
(D) Assertion is false, but Reason is true. in milk, very effectively aiding curd formation (B)


Ans through ongoing lactic acid production.

(C) Assertion is true, but Reason is false 25. Why are certain bacteria referred to as biofertilizers?
HIV is a retrovirus causing AIDS by infecting and (A) They directly kill pests on crops
destroying immune cells. Retroviruses like HIV (B) They degrade all plastics in soil
reverse-transcribe their RNA into DNA, very effectively (C) They fix or mobilize essential nutrients for plants
integrating into the host’s genome. Thus, the assertion (D) They generate high-quality compost without
that HIV causes AIDS is correct, but the reason is false microorganisms
because retroviruses do indeed fully integrate their

Ans
genetic material.
(C) They fix or mobilize essential nutrients for plants
23. Which type of immunity is gained by vaccination with Biofertilizers involve microorganisms that enrich soil
weakened pathogens? fertility by fixing atmospheric nitrogen, solubilizing
(A) Natural active immunity phosphorus, or otherwise making nutrients available
(B) Artificial active immunity to plants. Common examples include Rhizobium
(C) Natural passive immunity in legume nodules and mycorrhizal fungi assisting
(D) Artificial passive immunity nutrient uptake. By enhancing plant growth naturally,


Ans biofertilizers reduce reliance on chemical inputs, thereby
effectively promoting truly sustainable agriculture.
(B) Artificial active immunity
Artificial active immunity develops when an individual 26. Which of the following microbes does NOT help in
is deliberately exposed to weakened or killed pathogens sewage treatment?
via vaccination. The immune system responds by (A) Methanogenic bacteria
producing antibodies and memory cells, thus providing (B) Activated sludge bacteria
long-lasting protection. Natural immunity occurs (C) Fungal mycelia for secondary treatment
through infection or maternal antibodies, while passive (D) Pathogenic E. coli strains
immunity involves transfer of ready-made antibodies,

Ans
not active generation.
(D) Pathogenic E. coli strains
24. Match each microbe with its primary industrial Sewage treatment relies on microbes that break down
application: organic matter in primary, secondary, and anaerobic
digestion stages. Methanogenic bacteria and many
Column I Column II
bacterial or fungal communities help degrade waste.
1. Saccharomyces A. Biogas production However, pathogenic E. coli strains threaten public
cerevisiae health and do not assist waste decomposition; they
2. Penicillium notatum B. Curd formation require removal, not utilization, in treatment processes.
3. Methanobacterium C. Antibiotic production
27. Which combination of steps is essential in recombinant
4. Lactobacillus D. Baking and brewing
DNA technology?
Options: 1. Isolation of DNA

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 PRACTICE PAPER 11

2. Tying the DNA ends with ligatures 30. How do genetically modified (GM) crops differ from
3. Using restriction endonucleases traditionally bred crops?
4. Ligation of DNA fragments (A) GM crops are never disease-resistant
5. Amplification using PCR (B) GM crops are produced through conventional
(A) 1, 3, 4, 5 crossbreeding
(B) 1, 2, 3, 5 (C) GM crops involve specific gene manipulations
(C) 2, 4, 5 (D) GM crops only grow in greenhouses
(D) 3, 4, 5

Ans


Ans (C) GM crops involve specific gene manipulations
(A) 1, 3, 4, 5 Genetically modified crops are created by introducing,
Recombinant DNA technology involves isolating DNA modifying, or silencing specific genes using recombinant
(1), cutting it with restriction endonucleases (3), ligating DNA techniques. Traditional breeding relies on crossing
the resulting fragments into a vector (4), and amplifying plants with desirable traits over multiple generations.
the construct, often by PCR (5). Merely tying DNA ends GM approaches precisely target genes for disease
with ligatures (2) is not a standard procedure, so options resistance, stress tolerance, or improved nutrition, thus
1, 3, 4, and 5 are correct. greatly accelerating crop improvement compared to
conventional methods.
28. What is the role of “sticky ends” generated by restriction
enzymes in genetic engineering? 31. Which of the following is NOT an application of
(A) They prevent plasmid replication biotechnology in medicine?
(B) They facilitate complementary base pairing (A) Gene therapy
(C) They degrade foreign DNA (B) Stem cell technology
(D) They induce spontaneous mutations (C) Antibiotic production


Ans (D) Telepathic treatment

(B) They facilitate complementary base pairing

Ans

Sticky ends are overhanging single-stranded segments (D) Telepathic treatment
formed when restriction enzymes make staggered cuts Biotechnological advances in medicine include gene
in DNA. These ends can anneal with complementary therapy for genetic disorders, stem cell technology for
sequences from other DNA fragments cut by the same regenerative treatments, and antibiotic production using
enzyme. This alignment ensures stable joining of vector engineered microorganisms. Telepathic treatment,
and insert DNA, a key step in forming recombinant lacking valid scientific basis or use of biological systems,
molecules for cloning. does not fall under biotechnological applications.
Hence, it is not an established biotechnology-based
29. Which enzyme is used to synthesize cDNA from approach in medical practice.
mRNA?
(A) Restriction endonuclease 32. Match the following with their role in biotech
(B) Taq polymerase applications:
(C) Reverse transcriptase
Column I Column II
(D) DNA polymerase III
1. Bt toxin gene A. Gene therapy vector


Ans
2. Ti plasmid B. Genetically engineered to
(C) Reverse transcriptase contain beta-carotene
Reverse transcriptase synthesizes complementary DNA 3. Adenovirus C. Biological insect control
(cDNA) from an mRNA template, a very crucial step vector
in creating eukaryotic gene libraries free of introns.
4. Golden rice D. Vector from Agrobacterium
Restriction endonucleases cut DNA at specific sites,
tumefaciens
Taq polymerase amplifies DNA in PCR, and DNA
polymerase III extends primers during replication. Only Options:
reverse transcriptase converts RNA into DNA. (A) 1-C, 2-D, 3-A, 4-B
(B) 1-D, 2-C, 3-B, 4-A

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(C) 1-B, 2-A, 3-D, 4-C (A) 1, 2, 4

(D) 1-A, 2-B, 3-C, 4-D (B) 1, 2, 3, 5


Ans (C) 2, 4, 5
(D) 1, 3, 4
(A) 1-C, 2-D, 3-A, 4-B
The Bt toxin gene (1) provides biological insect control

Ans
(C). The Ti plasmid (2) from Agrobacterium tumefaciens (B) 1, 2, 3, 5
(D) is used as a vector to introduce genes into plants. Population size changes result from births (1), deaths
Adenovirus (3) serves as a common gene therapy (2), emigration (3), and immigration (5). Births and
vector (A). Golden rice (4) is genetically engineered for immigration increase population size, while deaths and
enhanced beta-carotene content (B) successfully. emigration decrease it. Biomagnification (4) concerns
pollutant concentration along food chains, not a direct
33. Why is mutualism beneficial for both species involved? factor altering population numbers, making 1, 2, 3, and
(A) Both species aggressively compete for resources 5 the correct combination.
(B) One species benefits, while the other is unaffected
(C) Each species gains a resource or advantage 36. Arrange the steps of energy flow in the correct sequence:
(D) It reduces biodiversity in the ecosystem 1. Herbivores consume plants


Ans 2. Plants capture sunlight
3. Primary carnivores eat herbivores
(C) Each species gains a resource or advantage 4. Secondary carnivores eat primary carnivores
Mutualism describes an interaction where both (A) 2-1-3-4
species derive benefits, such as nutrients, protection, (B) 1-2-3-4
or pollination services. Each organism contributes (C) 3-4-1-2
a service or resource the other lacks, creating a net (D) 2-3-1-4
positive outcome for both parties. This cooperation
fosters survival and reproductive success, thereby

Ans
enhancing ecological stability, biodiversity, and overall (A) 2-1-3-4
ecosystem resilience. Producers (plants) first capture solar energy (2).
Herbivores then consume plants (1), transferring energy
34. Which demographic parameter is defined as the number up the food chain. Primary carnivores feed on herbivores
of individuals born per unit time in a population? (3), and secondary carnivores consume the primary
(A) Birth rate carnivores (4). This linear sequence demonstrates the
(B) Death rate very typical, fundamental path of energy flow through
(C) Growth rate trophic levels in an ecosystem.
(D) Age distribution
37. Why is the energy transfer from one trophic level to the


Ans
next inefficient?
(A) Birth rate (A) All energy is converted to biomass
Birth rate measures the frequency of new individuals (B) Some energy is lost as heat and waste
entering a population through reproduction over a (C) Producers use no energy
specified period. It is often expressed as births per (D) Consumers always store 90% of energy
thousand individuals annually. Death rate tracks losses
from mortality, while growth rate reflects net change.

Ans
Age distribution shows how individuals are spread (B) Some energy is lost as heat and waste
across different age classes. Only a fraction of the energy assimilated by one trophic
level is passed to the next, with much lost as heat during
35. Which combination of factors directly influences metabolism and excreted waste. Consequently, biomass
population size changes? and energy availability diminish at higher trophic levels.
1. Birth rate This inefficiency underlies ecological pyramids and
2. Death rate limits the number of trophic levels in ecosystems.
3. Emigration
4. Biomagnification 38. How do pyramids of biomass differ from pyramids of
5. Immigration energy?

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 PRACTICE PAPER 11

(A) Biomass pyramids always remain upright habitat conservation, legal frameworks, and education
(B) Energy pyramids can be inverted ultimately yields the best outcomes.
(C) Biomass pyramids represent stored organic matter,
while energy pyramids show energy flow rates

Direction :Carefully read the case study provided and then
(D) There is no difference between them thoroughly answer the subsequent five questions.
In a rural region known for its diverse wildlife, a farmer


Ans noticed declining pollinators and soil fertility. Determined
(C) Biomass pyramids represent stored organic matter, to reverse the trend, she integrated organic farming
while energy pyramids show energy flow rates techniques, avoided chemical pesticides, and planted
Biomass pyramids illustrate the total dry weight (or flowering hedgerows to attract beneficial insects. She
mass) of organisms at each trophic level at a given time. also adopted a rotational cropping system with nitrogen-
Energy pyramids depict the flow of energy through fixing legumes and engaged in local seed exchange
trophic levels per unit area per unit time, always upright programs to preserve indigenous varieties. Furthermore,
because energy diminishes upward. Biomass pyramids she set aside wetland patches to nurture amphibians
can sometimes appear inverted, unlike energy pyramids. and aquatic organisms, significantly boosting ecological
balance. Community awareness sessions on pollinator
39. Which of the following does NOT enhance biodiversity conservation and habitat restoration supported her
conservation? efforts. These combined initiatives greatly improved crop
(A) Sacred groves yield and supported local pollinator species like bees and
(B) Wildlife sanctuaries butterflies. Over time, the farmer observed balanced pest
(C) Biopiracy populations, healthier soil, and increased biodiversity on
(D) Biosphere reserves her land, illustrating how sustainable practices can protect


Ans ecosystems while maintaining agricultural productivity.
(C) Biopiracy 41. Which method did the farmer use to maintain soil
Biodiversity conservation benefits from protected areas fertility?
like sacred groves, wildlife sanctuaries, and biosphere (A) Monoculture
reserves that safeguard habitats and species. Biopiracy, (B) Rotational cropping with legumes
however, involves exploiting biological resources or (C) Heavy pesticide application
traditional knowledge without proper authorization (D) Complete reliance on synthetic fertilizers
or benefit-sharing, greatly undermining conservation
efforts. Thus, it does not contribute to preserving

Ans
biodiversity or promoting equitable resource use. (B) Rotational cropping with legumes
The farmer employed rotational cropping with nitrogen-
40. Which strategy best addresses the loss of biodiversity? fixing legumes, a practice that naturally enriches the
(A) Widespread monoculture farming soil. Leguminous plants harbor symbiotic bacteria in
(B) Strict hunting policies without habitat preservation their root nodules, converting atmospheric nitrogen
(C) Habitat protection, legal regulations, and awareness into bioavailable forms. This reduces dependence
programs on synthetic fertilizers, helps sustain soil structure,
(D) Eliminating local seed varieties and supports healthier crop growth, thereby greatly


Ans benefiting multiple cropping seasons.
(C) Habitat protection, legal regulations, and awareness 42. Why did planting flowering hedgerows benefit the farm?
programs (A) They blocked all sunlight
Comprehensive biodiversity conservation involves (B) They released harmful chemicals
safeguarding habitats, enforcing protective legislation (C) They attracted beneficial insects
against overexploitation, and raising public awareness. (D) They reduced pollination
Monoculture reduces genetic variation; simply
banning hunting without preserving ecosystems is

Ans
insufficient; eliminating local seed varieties diminishes (C) They attracted beneficial insects
genetic diversity. Hence, a holistic approach uniting Flowering hedgerows offer nectar and pollen, inviting
helpful insects like pollinators and predators of crop

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pests. These beneficial insects assist in transferring (C) Balanced pest populations, healthier soil, and richer
pollen among blooms, significantly improving yields, biodiversity
and controlling pest populations naturally. By fostering Sustainable methods like crop rotation, wetland
ecological balance, the hedgerows reduce chemical conservation, and reduced chemical inputs create
pesticide use while supporting biodiversity and overall harmonious ecological conditions. Beneficial organisms
farm health. thrive, regulating pest species, while soil fertility
improves through natural nutrient cycles. This synergy
43. Which action mentioned did NOT help enhance leads to a more diverse array of flora and fauna,
biodiversity? significantly stabilizing yields and reinforcing overall
(A) Planting flowering hedgerows farm ecosystem health.
(B) Protecting wetland patches
(C) Using local seed exchange programs

Direction :Carefully read the case study provided and then
(D) Heavy use of chemical pesticides thoroughly answer the subsequent five questions.


Ans In a family with a history of thalassemia, a young couple
decided to seek genetic counseling before planning a
(D) Heavy use of chemical pesticides child. The counselor explained that thalassemia follows
Chemical pesticides very often harm non-target a Mendelian pattern, often requiring both parents to
organisms, reduce beneficial insect populations, and carry a mutated gene. By conducting a simple blood
contaminate soil and water. They disrupt natural test and analyzing their hemoglobin profiles, medical
ecological balance, curbing biodiversity gains. experts identified them as carriers. Understanding the
Conversely, practices like flowering hedgerows, wetland risks, the couple explored reproductive options such as
conservation, and local seed exchange encourage prenatal diagnosis and genetic testing. They learned
beneficial species, conserve habitats, and maintain about advanced reproductive technologies like IVF
genetic diversity, thereby significantly improving overall combined with pre-implantation genetic testing to
ecosystem health. ensure an unaffected embryo. Although these techniques
44. How does preserving local seed varieties promote involved ethical and financial considerations, the couple
biodiversity? recognized the importance of informed decision-making
(A) It introduces invasive species to mitigate inherited disease burdens. Ultimately, they
(B) It eliminates natural predators aimed to prevent passing on the disorder and promote
(C) It maintains genetic diversity in crops overall family health, illustrating how modern genetics
(D) It increases pesticide usage can empower individuals.

Ans 46. Which genetic pattern does thalassemia typically follow?

(C) It maintains genetic diversity in crops (A) Polygenic inheritance
Local or indigenous seed varieties carry region-specific (B) Chromosomal aneuploidy
traits, including resistance to local pests, diseases, (C) Mendelian inheritance
and climate conditions. Preserving these seeds fosters (D) Cytoplasmic inheritance
genetic variability within crop populations, reducing

Ans
vulnerability to environmental pressures. This diversity (C) Mendelian inheritance
underpins stable yields, ecosystem resilience, and the Thalassemia usually results from mutations in a single
capacity to continually adapt to evolving threats or gene affecting hemoglobin production. This fully aligns
changing conditions. with Mendelian inheritance, wherein a child inherits two
45. Which overarching outcome did the farmer witness gene copies, one from each parent. When both parents
after implementing sustainable practices? carry the mutant allele, offspring risk manifesting the
(A) Reduced soil health and fewer pollinators disorder or being carriers, depending on the specific
(B) Declining pest control and ecosystem imbalance inheritance pattern.
(C) Balanced pest populations, healthier soil, and 47. Which diagnostic method helped identify the couple as
richer biodiversity thalassemia carriers?
(D) Complete elimination of insects from the farm (A) Karyotyping


Ans (B) Hemoglobin profile analysis

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 PRACTICE PAPER 11

(C) Amniocentesis disorder’s inheritance risk. Ultrasound alone cannot

(D) Ultrasound imaging actively prevent or fully diagnose carrier status.


Ans 50. What was the couple’s primary motivation for exploring
(B) Hemoglobin profile analysis advanced reproductive technologies?
Hemoglobin profiling evaluates hemoglobin variants (A) Curiosity about new technology
and identifies abnormalities, revealing carrier status (B) Desire to ensure an unaffected offspring
for conditions like thalassemia. Karyotyping detects (C) Interest in genetically enhancing traits
chromosomal changes, whereas amniocentesis and (D) Wish to avoid medical procedures
ultrasound are prenatal procedures. By analyzing

Ans
hemoglobin chains and ratios, doctors confirm whether
individuals carry the defective gene responsible for (B) Desire to ensure an unaffected offspring
reduced or altered hemoglobin synthesis, confirming They sought to fully prevent transmitting thalassemia,
carrier status. a serious inherited genetic disorder, to their child. By
investigating advanced techniques like IVF with pre-
48. Assertion (A) : IVF with pre-implantation genetic implantation genetic testing, they could screen embryos
testing can prevent inheriting certain genetic disorders. for the mutation before implantation. This approach
Reason (R) : Pre-implantation testing screens embryos directly targets the hereditary risk, aligning with their
for mutations before implantation. goal of a healthy, unaffected child.
(A) Both Assertion and Reason are true, and Reason is
the correct explanation.

*************

(B) Both Assertion and Reason are true, but Reason is

not the correct explanation.
(C) Assertion is true, but Reason is false.
(D) Assertion is false, but Reason is true.


Ans
(A) Both Assertion and Reason are true, and Reason is
the correct explanation
Pre-implantation genetic testing examines embryos
conceived via IVF for specific mutations before transfer
to the uterus. By selecting healthy embryos, the risk of
passing on the disorder is seriously minimized. Thus, the
assertion is true, and the reason accurately explains how
embryo screening helps prevent inherited conditions in
at-risk couples.

49. Which procedure does NOT directly apply to preventing

thalassemia transmission?
(A) Prenatal diagnosis
(B) Genetic counseling
(C) Ultrasound for fetal imaging
(D) Pre-implantation genetic testing


Ans
(C) Ultrasound for fetal imaging
Ultrasound imaging primarily checks fetal growth,
structural anatomy, and viability but does not detect
specific genetic mutations causing thalassemia. In
contrast, prenatal diagnosis (chorionic villus sampling
or amniocentesis), genetic counseling, and pre-
implantation genetic testing directly address the

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PRACTICE PAPER 12

1. Which structure in the ovule ultimately develops into pollen tube, delivering sperm cells to the ovule. Non-
the seed coat? viable pollen either fails to hydrate or cannot extend a
(A) Nucellus pollen tube, disrupting fertilization. Maintaining pollen
(B) Integuments viability increases the likelihood of successful seed and
(C) Micropyle fruit set.
(D) Embryo sac
4. Which hormone triggers ovulation around the midpoint


Ans of the menstrual cycle?
(B) Integuments (A) Follicle-stimulating hormone (FSH)
Integuments are the protective layers surrounding (B) Luteinizing hormone (LH)
the ovule; after fertilization, they typically harden and (C) Prolactin
transform into the seed coat. The nucellus supplies (D) Oxytocin
nutrients and may persist or degenerate, while the

Ans
micropyle remains as a small pore. The embryo sac
houses the female gametophyte but does not form the (B) Luteinizing hormone (LH)
seed coat. A surge in luteinizing hormone (LH) around day 14
in a typical 28-day cycle induces ovulation, releasing
2. Which term describes the fusion of two male gametes the secondary oocyte from the dominant follicle.
with two different cells in the embryo sac? FSH promotes follicular growth, prolactin aids
(A) Triple fusion milk production, and oxytocin stimulates uterine
(B) Double fertilization contractions and milk ejection but does not initiate
(C) Pollination ovulation.
(D) Parthenocarpy
5. Which is NOT a function of the female reproductive


Ans system’s oviducts (fallopian tubes)?
(B) Double fertilization (A) Site of fertilization
Double fertilization in flowering plants involves one (B) Conduit for sperm to meet ovum
male gamete fusing with the egg, forming the zygote, (C) Implantation of the embryo
and the other male gamete fusing with the central (D) Transport of fertilized ovum to uterus
cell to create the endosperm. This process is unique

Ans
to angiosperms, ensuring simultaneous embryo and
endosperm formation. Triple fusion refers specifically (C) Implantation of the embryo
to the fusion producing endosperm. The fallopian tubes guide the ovum, allow fertilization in
the ampullary region, and transport the fertilized ovum
3. Why does pollen viability matter for successful toward the uterus. Implantation, however, occurs in the
fertilization? uterine endometrium, not in the tubes. Thus, the oviduct
(A) Non-viable pollen reduces seed size facilitates fertilization and early embryo movement but
(B) Viable pollen can germinate and form a pollen tube does not support embryonic implantation.
(C) Viable pollen always self-pollinates
6. Which structure in the testes produces sperm?
(D) Non-viable pollen is required for cross-breeding
(A) Leydig cells


Ans (B) Sertoli cells
(B) Viable pollen can germinate and form a pollen tube (C) Rete testis
Pollen viability ensures that the male gametophyte (D) Seminiferous tubules
can germinate on the stigma and form a functional

Ans

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 PRACTICE PAPER 12

(D) Seminiferous tubules (B) Both Assertion and Reason are true, but Reason is
Seminiferous tubules are the specific sites where not the correct explanation.
spermatogenesis occurs, producing mature sperm cells. (C) Assertion is true, but Reason is false.
Sertoli cells within these tubules support developing (D) Assertion is false, but Reason is true.
sperm, while Leydig cells secrete testosterone in the

Ans
interstitial spaces. Rete testis is a network collecting
sperm before they move to the epididymis, but not the (C) Assertion is true, but Reason is false
actual site of sperm production. Amniocentesis extracts and analyzes amniotic fluid
for fetal cells, revealing chromosomal or metabolic
7. Which strategy is most effective for preventing sexually disorders. While it helps diagnose conditions like
transmitted diseases (STDs)? Down’s syndrome, it does not cure them. Identifying a
(A) Periodic ultrasound scans disorder guides prospective parents and clinicians but
(B) Maintaining complete personal hygiene and using does not offer a direct therapeutic intervention for the
protection fetus.
(C) Consuming high-protein diets
10. How does codominance differ from incomplete
(D) Engaging only in polygamous relationships
dominance?


Ans (A) In codominance, neither allele is expressed
(B) Maintaining complete personal hygiene and using (B) In incomplete dominance, both alleles are fully
protection expressed
STD prevention primarily relies on safe sexual practices, (C) In codominance, both alleles are fully expressed
such as consistent use of condoms and proper personal without blending
hygiene. Regular health checkups and communication (D) There is no difference
with partners further reduce transmission risks.

Ans
Diet and ultrasound scans do not prevent STDs, and
polygamous relationships without protection elevate (C) In codominance, both alleles are fully expressed
the risk rather than mitigate it. without blending
In codominance, each allele in a heterozygote expresses
8. Which technique involves fertilizing an ovum outside distinctly (e.g., AB blood group), while incomplete
the body and then transferring the embryo to the uterus? dominance produces an intermediate phenotype (e.g.,
(A) GIFT pink flowers from red and white alleles). Both processes
(B) IVF-ET deviate from classic dominance, but only codominance
(C) IUI shows simultaneous, full expression of both alleles.
(D) MTP
11. Which genotype will express the dominant trait in


Ans incomplete dominance?
(B) IVF-ET (A) Only homozygous dominant
In Vitro Fertilization and Embryo Transfer (IVF-ET) (B) Only homozygous recessive
entails collecting ova from the ovary, fertilizing them (C) Both homozygous dominant and heterozygous, but
externally with sperm, and transferring the resulting with different phenotypes
embryo into the uterus. GIFT (Gamete Intra-Fallopian (D) Only heterozygous
Transfer) places gametes in the fallopian tube, IUI

Ans
(Intrauterine Insemination) deposits sperm in the
uterus, and MTP stands for medical termination of (C) Both homozygous dominant and heterozygous, but
pregnancy. with different phenotypes
In incomplete dominance, the homozygous dominant
9. Assertion (A) : Amniocentesis is used to identify genotype exhibits the full dominant phenotype, while
chromosomal abnormalities in the fetus. the heterozygous genotype shows an intermediate
Reason (R) : Amniocentesis directly cures genetic phenotype. Homozygous recessive expresses the
diseases in the fetus. recessive trait. Thus, both homozygous dominant and
(A) Both Assertion and Reason are true, and Reason is heterozygous individuals display a “dominant” trait,
the correct explanation.

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though the heterozygote’s phenotype is partially reduced processing. Only the structural gene portion directly
or blended. translates into a protein.

12. Which of the following is NOT typically inherited via 15. Which component carries amino acids to the ribosome
sex-linked recessive genes in humans? during translation?
(A) Hemophilia (A) mRNA
(B) Red-green color blindness (B) tRNA
(C) Sickle cell anemia (C) rRNA
(D) Duchenne muscular dystrophy (D) snRNA


Ans

Ans
(C) Sickle cell anemia (B) tRNA
Hemophilia, red-green color blindness, and Duchenne Transfer RNA (tRNA) molecules attach to specific
muscular dystrophy often follow an X-linked recessive amino acids and present anticodons complementary
pattern, more commonly affecting males. Sickle to mRNA codons at the ribosome. Messenger RNA
cell anemia, however, is an autosomal recessive (mRNA) provides the codon sequence, ribosomal RNA
condition involving a mutation in the beta-globin (rRNA) forms the core ribosome structure, and snRNA
gene on chromosome 11, not inherited through the X aids in splicing. Thus, tRNA delivers amino acids for
chromosome. polypeptide synthesis.

13. Assertion (A) : Males determine the sex of the child in 16. Why is the lac operon induced in the presence of lactose?
humans. (A) Lactose mutates the repressor
Reason (R) : A female’s gametes carry only an X (B) Lactose acts as an inducer, binding the repressor
chromosome, while male gametes can be X or Y. (C) Glucose directly inhibits mRNA synthesis
(A) Both Assertion and Reason are true, and Reason is (D) The structural genes are always turned on
the correct explanation.

Ans
(B) Both Assertion and Reason are true, but Reason is
not the correct explanation. (B) Lactose acts as an inducer, binding the repressor
(C) Assertion is true, but Reason is false. In the lac operon, lactose (or allolactose) binds to the
(D) Assertion is false, but Reason is true. repressor protein, altering its conformation so it can no
longer bind the operator. This frees RNA polymerase


Ans to transcribe the operon’s genes, enabling lactose
(A) Both Assertion and Reason are true, and Reason is metabolism. Without lactose, the repressor stays bound,
the correct explanation preventing gene expression.
Female gametes invariably contain an X chromosome,
17. Which combination of processes leads to RNA synthesis
while male gametes can have either X or Y. If a Y-carrying
sperm fertilizes the ovum, a male (XY) results. If an and subsequent protein formation?
X-bearing sperm fertilizes it, a female (XX) forms. Thus, 1. Replication
the male’s gamete decides the offspring’s sex. 2. Transcription
3. Translation
14. Which segment of DNA codes for a polypeptide? 4. Reverse transcription
(A) Promoter 5. Splicing
(B) Operon (A) 1, 4, and 5
(C) Structural gene (B) 2, 3, and 5
(D) Introns (C) 2, 4, and 5


Ans (D) 1, 2, and 3

(C) Structural gene

Ans

A structural gene is the specific DNA segment that (B) 2, 3, and 5
encodes a polypeptide. Promoters regulate where Genes are transcribed (2) into pre-mRNA, which
transcription begins, operons are functional units often undergoes splicing (5) to remove introns. The
containing structural genes plus regulatory regions, and mature mRNA is then translated (3) into a polypeptide.
introns are noncoding segments removed during RNA Replication (1) duplicates DNA, and reverse

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 PRACTICE PAPER 12

transcription (4) synthesizes DNA from RNA but is not (A) Bacterium
part of typical gene expression in eukaryotes. (B) Virus
(C) Protozoan
18. Which scientist is credited with proposing the theory of (D) Fungus
natural selection in tandem with Charles Darwin?
(A) Alfred Russel Wallace

Ans
(B) Gregor Mendel (C) Protozoan
(C) Jean-Baptiste Lamarck Amoebiasis is primarily caused by the protozoan
(D) Thomas Malthus Entamoeba histolytica. Bacterial pathogens cause


Ans diseases like pneumonia and typhoid, while viruses
cause ailments like the common cold and dengue.
(A) Alfred Russel Wallace Fungal pathogens lead to ringworm infections, but
Alfred Russel Wallace independently conceived the idea amoebiasis originates from a protozoan parasite.
of evolution by natural selection and corresponded with
Darwin. Their combined insights prompted Darwin 22. Which disease is characterized by malignant growth
to publish “On the Origin of Species.” Mendel laid due to uncontrolled cell division?
foundations of genetics, Lamarck proposed inheritance (A) Tuberculosis
of acquired traits, and Malthus influenced Darwin’s (B) Cancer
thinking on population pressure. (C) Filariasis
(D) Typhoid
19. Why does mutation fuel the process of evolution?
(A) Mutations prevent genetic variation

Ans
(B) Mutations reduce survival (B) Cancer
(C) Mutations introduce new alleles Cancer involves uncontrolled cell division forming
(D) Mutations maintain all alleles at equilibrium tumors, which may invade surrounding tissues or spread


Ans to distant sites (metastasis). Tuberculosis is a bacterial
infection, filariasis is a parasitic disease affecting
(C) Mutations introduce new alleles lymphatic vessels, and typhoid is caused by Salmonella
Mutations alter the genetic material, creating novel typhi. Cancer results from genetic and environmental
alleles or variations in existing ones. This fresh genetic factors disturbing cell regulation.
diversity provides raw material on which natural
selection can act. While some mutations are harmful, 23. Which approach best prevents the spread of HIV/AIDS?
others may confer advantages in certain environments, (A) Sharing needles among trusted friends
thus fueling evolutionary change across generations. (B) Practice of safe sex, screening blood, and avoiding
needle sharing
20. Which of the following does NOT directly support (C) Avoiding vaccination programs
evolution? (D) Self-prescribing antibiotics frequently
(A) Fossil records
(B) Comparative embryology

Ans
(C) DNA sequence homology (B) Practice of safe sex, screening blood, and avoiding
(D) Lunar cycle observations needle sharing


Ans HIV spreads via unprotected sexual contact,
contaminated blood transfusions, and shared needles.
(D) Lunar cycle observations Thus, consistent condom use, proper blood screening,
Evolutionary evidence arises from paleontological and refraining from needle sharing are vital in
records (fossils), comparative embryology, and prevention. Antibiotics do not target viruses, and
molecular data like DNA or protein sequences. These ignoring vaccinations or relying on “trusted” needle
show relationships among species and ancestral sharing does not halt HIV transmission.
patterns. Lunar cycles relate to moon phases, tides,
and behavior patterns in some organisms but do not 24. Which set of microbes are useful for industrial
demonstrate how species evolve over time. fermentation processes?
1. Saccharomyces cerevisiae
21. Which pathogen type causes amoebiasis? 2. Penicillium roqueforti

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3. HIV inhibit these helpful microbes, undermining the very

4. Lactobacillus bulgaricus purpose of biofertilizers. Hence, employing harmful
5. Ebola virus chemicals alongside biofertilizers is counterproductive
(A) 1, 2, and 4 to sustainable, microbe-based soil enrichment.
(B) 2, 3, and 5
27. Arrange these steps in the correct order for producing
(C) 1, 4, and 5
(D) 3, 4, and 5 recombinant insulin:
1. Synthesis of A and B chains separately


Ans 2. Restriction enzyme digestion
(A) 1, 2, and 4 3. Ligation into plasmid vectors
Saccharomyces cerevisiae (yeast) is employed in bread, 4. Joining of chains to form functional insulin
beer, and wine making; Penicillium roqueforti helps 5. Transformation into bacterial host
in cheese ripening; Lactobacillus bulgaricus ferments (A) 2-3-5-1-4
dairy into yogurt. HIV and Ebola are viruses causing (B) 2-1-3-5-4
severe diseases, not involved in beneficial industrial (C) 1-2-3-4-5
fermentation. (D) 2-5-3-1-4

25. Why are Baculoviruses considered beneficial as

Ans

biocontrol agents? (A) 2-3-5-1-4
(A) They attack beneficial insects First, the desired DNA fragments are cut by restriction
(B) They produce antibiotic residues enzymes (2), then inserted into plasmids (3). These
(C) They specifically target insect pests without recombinant plasmids are transformed into bacterial
harming other organisms hosts (5). Each host separately produces insulin A and B
(D) They pollute water sources severely polypeptide chains (1). Finally, the chains are combined


Ans (4) to form functional human insulin.

(C) They specifically target insect pests without harming 28. Why do plasmids serve as effective cloning vectors?
other organisms (A) They are large and hard to manipulate
Baculoviruses selectively infect insect pests, especially (B) They lack replication origins
Lepidopteran larvae, minimizing damage to non- (C) They often contain selectable markers and replicate
target species. This specificity makes them excellent for independently
biological pest control, reducing reliance on chemical (D) They are immune to restriction enzymes
pesticides that can harm beneficial organisms. Properly

Ans
applied, baculoviruses pose minimal environmental
toxicity and preserve overall biodiversity. (C) They often contain selectable markers and replicate
independently
26. Which practice does NOT align with the safe use of Plasmids are small, circular DNA molecules carrying
biofertilizers? their own origin of replication. They typically have
(A) Employing Rhizobium for legume cultivation antibiotic resistance genes or other markers for easy
(B) Using mycorrhizal fungi for better phosphate selection of transformed cells, and they replicate
uptake independently of the bacterial chromosome. Their
(C) Spraying toxic chemical fungicides regularly with manageability and selectable features make them
biofertilizers excellent vectors for gene cloning.
(D) Introducing Azotobacter to increase nitrogen
29. Which crop is commonly engineered with the Bt gene to
content
protect against insect pests?


Ans (A) Bt Rice
(C) Spraying toxic chemical fungicides regularly with (B) Bt Wheat
biofertilizers (C) Bt Cotton
Biofertilizers rely on beneficial microbes like Rhizobium, (D) Bt Soybean
Azotobacter, or mycorrhizae to enhance soil fertility.

Ans
Consistently applying toxic fungicides can kill or
(C) Bt Cotton

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 PRACTICE PAPER 12

Bt cotton harbors a gene from Bacillus thuringiensis Predation involves a predator consuming a prey
producing a toxin lethal to certain insect larvae, organism, often causing the prey’s death. Competition
especially bollworms. While research exists for other sees organisms vie for the same resources, mutualism
Bt-engineered crops, Bt cotton stands as the widely benefits both partners, and commensalism benefits
commercialized example. This genetic intervention one without harming the other. Predation is a direct
significantly reduces pesticide use and crop losses from consumptive interaction driving many ecological
bollworm infestation. adaptations.

30. How does gene therapy differ from vaccination? 33. Assertion (A) : Pyramids of energy in ecosystems can
(A) Gene therapy introduces weakened pathogens be inverted.
(B) Vaccination corrects existing genetic disorders Reason (R) : Energy decreases at each succeeding
(C) Gene therapy aims to fix or replace faulty genes, trophic level due to losses as heat and waste.
while vaccination trains the immune system (A) Both Assertion and Reason are true, and Reason is
(D) Both are used interchangeably the correct explanation.


Ans (B) Both Assertion and Reason are true, but Reason is
not the correct explanation.
(C) Gene therapy aims to fix or replace faulty genes, (C) Assertion is false, but Reason is true.
while vaccination trains the immune system (D) Assertion is true, but Reason is false.
Vaccines expose the body to antigens—either weakened
pathogens or fragments—so the immune system

Ans
develops memory and protection. Gene therapy, (C) Assertion is false, but Reason is true
however, attempts to rectify or replace a defective gene Energy pyramids are always upright because each level
responsible for a disorder. These distinct strategies receives less energy than the previous one, primarily
address different health issues, reflecting separate due to heat and metabolic losses. Biomass pyramids can
underlying biological principles. sometimes be inverted, but energy cannot accumulate
going upwards. Thus, the reason is correct, but the
31. Which factor most strongly affects the size of a assertion about inverted energy pyramids is false.
population in a stable environment?
(A) Overuse of inorganic fertilizers 34. Why is productivity generally higher in tropical regions
(B) Immigration and emigration compared to polar ones?
(C) Random geological events (A) Tropical regions have fewer predators
(D) Irregular gene expression (B) Polar areas receive more sunlight


Ans (C) Warm temperatures and ample rainfall support
abundant plant growth
(B) Immigration and emigration (D) Tropical latitudes have no decomposers
In a relatively stable environment, birth and death rates
often balance out. However, the influx (immigration)

Ans
or departure (emigration) of individuals can quickly (C) Warm temperatures and ample rainfall support
shift population size. Overuse of fertilizers, geological abundant plant growth
events, or gene expression variabilities may influence Tropical areas typically have year-round warmth,
populations indirectly but are typically less immediate high moisture availability, and longer growing
than migration changes. seasons, leading to dense vegetation and high primary
productivity. Polar regions have shorter summers, less
32. Which interaction describes an organism feeding on sunlight, and colder climates, limiting plant growth.
another living organism, usually killing it? Predators or decomposers do not primarily dictate the
(A) Competition fundamental productivity of these ecosystems.
(B) Mutualism
(C) Predation 35. Which activity does NOT promote biodiversity?
(D) Commensalism (A) Establishing national parks


Ans (B) Habitat destruction and fragmentation
(C) Reducing overexploitation of species
(C) Predation (D) Preserving genetic diversity in seed banks

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Ans 38. Assertion (A) : In most ecosystems, the number of

(B) Habitat destruction and fragmentation primary producers is greater than the number of apex
Habitat destruction and fragmentation severely threaten predators.
biodiversity by isolating populations, reducing gene Reason (R) : Energy transfer between trophic levels is
flow, and eliminating critical resources. Establishing highly efficient, allowing top predators to outnumber
protected areas, curbing overexploitation, and storing primary producers.
seeds in banks all safeguard species and genetic variety, (A) Both A and R are true, and R is the correct
enhancing conservation. Destroying habitats directly explanation of A
undermines these conservation efforts. (B) Both A and R are true, but R is not the correct
explanation of A
36. Which combination of conservation strategies is vital (C) A is true, but R is false
for protecting endangered species? (D) A is false, but R is true
1. In-situ conservation (national parks, sanctuaries)


Ans
2. Ex-situ conservation (zoos, seed banks)
3. Monoculture promotion (C) A is true, but R is false
4. Controlled hunting for profit Ecosystems usually have more producers than top-level
5. Community participation and awareness consumers, forming a pyramid of numbers. However,
(A) 1, 2, and 5 energy transfer is not highly efficient—only about 10%
(B) 1, 3, and 4 moves up each level—so apex predators are fewer than
(C) 2, 4, and 5 producers. Therefore, the assertion is correct, but the
(D) 3, 4, and 5 reason, stating transfer is “highly efficient,” is false


Ans 39. Which hormone primarily triggers ovulation by surging
(A) 1, 2, and 5 around the middle of the menstrual cycle?
Protecting endangered species typically combines in- (A) Follicle-Stimulating Hormone facilitating follicular
situ measures (1) to preserve habitats, ex-situ methods development
(2) like zoos or seed banks for critical backup, and (B) Luteinizing Hormone causing rupture of the
public engagement (5) promoting sustainable practices. mature follicle
Monoculture (3) reduces biodiversity, and hunting (C) Prolactin stimulating milk production postpartum
for profit (4) undermines conservation unless tightly (D) Oxytocin promoting uterine contractions during
regulated with specific goals and oversight. childbirth


Ans
37. Which of the following microbes is used in the
commercial production of citric acid? (B) Luteinizing Hormone
(A) Aspergillus niger A sudden rise in Luteinizing Hormone (LH) around
(B) Acetobacter aceti day 14 triggers the dominant follicle to release the ovum
(C) Penicillium chrysogenum from the ovary. This event, called ovulation, marks the
(D) Clostridium acetobutylicum transition from the follicular phase to the luteal phase,
preparing the female reproductive tract for possible


Ans
fertilization and embryo implantation. It is crucial
(A) Aspergillus niger
Aspergillus niger, a fungus, is widely employed in 40. Examine these statements about factors leading to
industrial processes to produce citric acid. Under biodiversity loss:
controlled fermentation conditions, it metabolizes 1. Habitat destruction
sugars and accumulates citric acid in large amounts. 2. Overexploitation of resources
This compound is then extracted and purified for use 3. Invasive species introduction
in beverages, pharmaceuticals, and other applications, 4. Artificial selection enhancing genetic variation
making Aspergillus niger essential for commercial citric Which combination of statements aggravate biodiversity
acid production loss?
(A) 1, 2, and 3 only
(B) 2, 3, and 4 only
(C) 1 and 4 only

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 PRACTICE PAPER 12

(D) 1, 2, 3, and 4 (C) It clogged waterways and reduced oxygen

Ans (D) It solely boosted fishing profits

(A) 1, 2, and 3 only

Ans

Habitat destruction, overexploitation, and invasive (C) It clogged waterways and reduced oxygen
species heavily contribute to biodiversity decline. Water hyacinth grows rapidly, forming thick surface
Artificial selection usually narrows genetic diversity in layers that block sunlight penetration, curtailing
domesticated species but doesn’t necessarily enhance it photosynthesis in submerged plants. This lowers
in wild populations. The listed anthropogenic pressures dissolved oxygen, vital for aquatic life. Fish suffer from
remain primary threats, underscoring the need for hypoxic conditions and restricted movement through
sustainable practices and strict biosecurity measures congested channels, leading to reduced populations and
economic impacts on fishing communities.


Direction :Carefully read the case study provided and then
thoroughly answer the subsequent five questions. 43. Which measure did NOT help counter the invasive
A large wetland region, once home to abundant fish and weed problem?
migratory birds, experienced a surge in invasive water (A) Harvesting water hyacinth for compost
hyacinth. This fast-growing aquatic weed competed (B) Introducing native aquatic plants
with native plant species and clogged waterways, (C) Creating handicrafts from hyacinth
reducing oxygen levels and threatening fish populations. (D) Allowing uncontrolled weed expansion
Local communities relied on fishing for livelihood but

Ans
found catches dwindling. In response, conservationists
worked with villagers to harvest water hyacinth for (D) Allowing uncontrolled weed expansion
composting and handicraft making, cutting back its The case mentions methods to control water hyacinth—
spread. Simultaneously, an ecological restoration team harvesting for compost and handicrafts, alongside
introduced native aquatic plants to restore habitat quality. reintroducing native species. Permitting the invasive
By promoting awareness of the wetland’s importance for weed’s unchecked growth worsens clogging and oxygen
bird migration and fish breeding, stakeholders recognized depletion. Therefore, taking no action fails to improve
that sustainable management practices—like regulated wetland health, unlike the other interventions that curb
fishing seasons and weed control—could improve water or repurpose hyacinth.
quality, safeguard biodiversity, and maintain economic 44. Why is regulating fishing seasons beneficial for the
benefits for the local population. wetland community?
41. Which invasive species disrupted the wetland ecosystem (A) It depletes fish stocks faster
in the case study? (B) It allows fish populations to reproduce and recover
(A) Water lettuce (C) It discourages tourism
(B) Water hyacinth (D) It eliminates all predatory fish
(C) Lotus

Ans
(D) Native reeds (B) It allows fish populations to reproduce and recover


Ans Restricting fishing to certain times or seasons ensures
(B) Water hyacinth that key breeding periods are undisturbed, granting fish
The case study explicitly identifies water hyacinth as stocks the chance to spawn and maintain sustainable
the invasive aquatic weed. It forms dense mats on the numbers. Overfishing without regulation leads to
water’s surface, blocking sunlight, depleting oxygen, and population collapse, but controlled harvesting balances
outcompeting native flora. This reduces fish populations economic needs with long-term ecological stability and
and hinders local livelihoods, making water hyacinth a continued community benefits.
prime example of a destructive invasive species. 45. Which outcome exemplifies the success of the wetland
42. How did invasive water hyacinth impact fish restoration efforts?
populations? (A) Complete eradication of all aquatic plants
(A) It provided extra food for fish (B) Higher fish catches, restored habitats, and stable
(B) It increased oxygen levels community livelihoods
(C) Banning local involvement in resource use

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(D) Permanent replacement of wetlands with farmland (C) It halted bacterial metabolism without detection


Ans (D) It produced no visible signal

(B) Higher fish catches, restored habitats, and stable

Ans

community livelihoods (B) It changed color via a reporter gene
Success is seen in balanced ecological restoration that The biotech approach involved inserting a reporter gene
boosts fish populations, maintains bird migration into the phage, yielding a color change when the phage
routes, and secures local economic interests. The case successfully infected target bacteria. This visible signal
highlights improved water quality, weed management, dramatically speeds testing by making contamination
and community cooperation. Eradicating all plants readily apparent. Without a reporter, detection would
or converting wetlands are counterproductive, while remain reliant on slower or more complex measurement
excluding local residents often undermines conservation techniques.
goals.
48. Which factor did NOT favor the adoption of this new


Direction :Carefully read the case study provided and then test?
thoroughly answer the subsequent five questions. (A) Reduced detection time
A biotechnology startup aimed to develop a method to (B) Ability to prevent contaminated milk distribution
detect pathogenic bacteria in milk quickly. Traditional (C) Increased economic losses due to lengthy recalls
culture methods took days, risking public health concerns (D) Biosafety measures ensuring controlled phage
if contaminated batches reached consumers. The scientists release
used a genetically modified bacteriophage carrying a

Ans
reporter gene that produced a visible color change in the
presence of targeted bacterial strains. By engineering this (C) Increased economic losses due to lengthy recalls
phage, the detection window dropped to a few hours. The test actually reduced potential losses by rapidly
Following trials in dairy plants, the rapid test system catching contaminated batches, thus avoiding large-
prevented distribution of tainted milk and reduced scale recalls. Faster detection prevents distribution of
economic losses from widespread recalls. Although there unsafe milk, benefiting public health and saving costs.
were initial debates about releasing genetically modified Proper biosafety controls also address concerns about
phages, strict biosafety protocols and regulatory guidelines using genetically modified phages. Hence, increased
ensured controlled usage. Eventually, this innovative losses do not favor the system.
approach demonstrated how biotechnology can safeguard 49. Assertion (A) : Strict biosafety protocols were
food supplies while minimizing testing delays. implemented for the GM phages.
46. What was the primary goal of the biotechnology startup? Reason (R) : Genetically modified organisms can pose
(A) To modify dairy cows genetically risks if released without regulation.
(B) To produce new flavors in milk (A) Both Assertion and Reason are true, and Reason is
(C) To detect pathogenic bacteria in milk quickly the correct explanation.
(D) To promote manual milk-testing methods (B) Both Assertion and Reason are true, but Reason is
not the correct explanation.


Ans (C) Assertion is true, but Reason is false.
(C) To detect pathogenic bacteria in milk quickly (D) Assertion is false, but Reason is true.
The case explicitly states the startup intended to shorten

Ans
detection times for bacterial contaminants in milk.
Traditional culture-based methods were slow, risking (A) Both Assertion and Reason are true, and Reason is
public health if contaminated milk reached consumers. the correct explanation
Hence, the researchers engineered a bacteriophage with GM bacteriophages, like other genetically modified
a reporter gene to rapidly identify pathogenic bacteria. entities, could impact ecosystems if mishandled.
Therefore, strict containment and usage protocols
47. How did the modified bacteriophage indicate bacterial are essential. The reason accurately explains why the
presence? assertion is valid: regulating GMO releases prevents
(A) It destroyed all microorganisms unintended environmental effects, justifying the
(B) It changed color via a reporter gene mandatory biosafety measures for these phages.

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 PRACTICE PAPER 12

50. What core benefit did this rapid phage-based test

provide to the dairy industry?
(A) Eliminated all bacteria in milk
(B) Prevented any future need for regulatory oversight
(C) Significantly shortened detection time and
minimized recall costs
(D) Allowed distribution of contaminated milk without
consequences


Ans
(C) Significantly shortened detection time and
minimized recall costs
By cutting detection windows from days to hours, the
biotech method enabled quicker intervention and
quarantine of tainted batches. This rapid response
limited contaminated milk shipments, reducing large-
scale recalls and protecting public health. It did not
eliminate bacteria outright or bypass regulation but
streamlined safety measures effectively.

*************

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PRACTICE PAPER 13

1. Which cell of a mature pollen grain eventually grows Apomixis is a reproductive process where seeds
into the pollen tube? form without the fusion of male and female gametes,
(A) Exine cell bypassing typical fertilization. In citrus, certain
(B) Vegetative cell nucellar cells can develop into embryos, leading to
(C) Generative cell seed formation genetically identical to the parent.
(D) Intine cell This preserves desirable traits but significantly reduces


Ans overall genetic variability in offspring populations.

(B) Vegetative cell 4. Which of the following is NOT a function of the Sertoli
The vegetative cell, called the tube cell, initiates growth cells in the testis?
of the pollen tube after pollination. This tube travels (A) Providing nutrition to developing sperm
through the style to carry the sperm nuclei produced (B) Facilitating sperm release into the lumen
by the generative cell. Exine and intine refer to pollen (C) Secreting testosterone
wall layers, which do not form the tube, highlighting the (D) Forming the blood-testis barrier
vegetative cell’s role.

Ans
2. Why does pollen-pistil interaction help prevent self- (C) Secreting testosterone
pollination in many flowering plants? Leydig cells secrete testosterone, not Sertoli cells. Sertoli
(A) It allows pollinators to sense flower color changes cells nourish developing sperm, regulate their release
(B) It identifies incompatible pollen and inhibits into seminiferous tubules, and maintain the blood-testis
germination barrier. They also produce certain signaling molecules
(C) It accelerates double fertilization but do not produce testosterone. Thus, secretion of
(D) It ensures more nectar production testosterone is most distinctly carried out by interstitial


Ans (Leydig) cells in the testis.

(B) It identifies incompatible pollen and inhibits 5. Which event marks the transition from follicular phase
germination to luteal phase in the human menstrual cycle?
Pollen-pistil interaction involves molecular recognition (A) Menstruation
between stigma and pollen. If pollen is genetically (B) Ovulation
similar or incompatible, the pistil signals prevent (C) Implantation
tube formation or growth, effectively blocking self- (D) Endometrial thickening
pollination. This mechanism promotes genetic diversity

Ans
by favoring cross-pollination, helping plants avoid
potentially deleterious inbreeding effects and maintain (B) Ovulation
healthier, more robust, and stable offspring. Ovulation is triggered by a surge in luteinizing hormone,
releasing the secondary oocyte from the mature Graafian
3. Which term refers to producing seeds without follicle. After this, the remnant follicle transforms
fertilization, as sometimes seen in citrus plants? into the corpus luteum, marking the start of the luteal
(A) Parthenogenesis phase. This shift is crucial for possible implantation and
(B) Apomixis maintenance of early pregnancy if fertilization occurs.
(C) Polyembryony
6. Assertion (A) : Fertilization in humans typically occurs
(D) Parthenocarpy
in the fallopian tube.


Ans Reason (R) : The ovum remains viable in the uterus for
(B) Apomixis several days awaiting sperm.

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 PRACTICE PAPER 13

(A) Both Assertion and Reason are true, and Reason is regulate hormones to prevent ovulation. Thus, options 1
the correct explanation. and 2 are barriers, 3 is IUD, 4 is oral contraception.
(B) Both Assertion and Reason are true, but Reason is
9. Why is medical termination of pregnancy (MTP)
not the correct explanation.
(C) Assertion is true, but Reason is false. recommended to be performed during the first
(D) Assertion is false, but Reason is true. trimester?
(A) Less hormonal influence


Ans (B) High fetal movement
(C) Assertion is true, but Reason is false (C) Lower risk of complications
Human fertilization usually happens in the ampullary (D) Enhanced organogenesis
region of the fallopian tube shortly after ovulation. The

Ans
released ovum is viable for about 24 hours in the tube,
not the uterus, awaiting sperm entry. Thus, while the (C) Lower risk of complications
assertion is correct, the reason provided is inaccurate The first trimester is generally considered safer for MTP
regarding ovum viability location and duration. because the fetus is less developed, and the procedure
is simpler, with reduced surgical or pharmacological
7. Which procedure involves inserting a small amount complications. As pregnancy advances, maternal and
of amniotic fluid into a test tube to screen for genetic fetal risks increase. Therefore, performing MTP earlier
abnormalities? lowers potential health hazards for both the pregnant
(A) IVF individual and the fetus.
(B) Amniocentesis
10. Match the following genetic terms with their
(C) ZIFT
(D) GIFT descriptions:

Ans Column I Column II

(B) Amniocentesis 1. Pleiotropy A. Multiple alleles contribute
Amniocentesis is a prenatal diagnostic technique that to a single phenotype
collects amniotic fluid, containing fetal cells, via a 2. Codominance B. Both alleles express equally
needle inserted into the amniotic sac. These cells are in heterozygote
then analyzed for chromosomal or genetic disorders. 3. Incomplete C. One gene influences
Although valuable for early detection, misuse for dominance multiple traits
sex determination can lead to ethical issues, so its 4. Polygenic D. Heterozygote shows
application is regulated. inheritance intermediate phenotype
8. Which combination of birth control methods is correct Options:
regarding barrier methods and intrauterine devices? (A) 1-C, 2-B, 3-D, 4-A
1. Condom (B) 1-D, 2-A, 3-B, 4-C
2. Diaphragm (C) 1-B, 2-D, 3-C, 4-A
3. Copper T (D) 1-A, 2-D, 3-C, 4-B
4. Oral Pill

Ans
(A) 1,2 are IUDs; 3,4 are barriers
(A) 1-C, 2-B, 3-D, 4-A
(B) 1,3 are barriers; 2,4 are IUDs
Pleiotropy (1) describes a single gene affecting several
(C) 1,2 are barriers; 3 is an IUD; 4 is oral contraception
traits (C). Codominance (2) involves both alleles fully
(D) 2,3 are barriers; 1,4 are IUDs
expressing in heterozygotes (B). Incomplete dominance


Ans (3) shows an intermediate phenotype in heterozygotes
(C) 1,2 are barriers; 3 is an IUD; 4 is oral contraception (D). Polygenic inheritance (4) arises from multiple
Condoms and diaphragms are barrier methods genes or alleles contributing to a single characteristic
preventing sperm from reaching the egg. Copper T, an (A), truly demonstrating complex genetic patterns.
intrauterine device, is placed in the uterus to hinder
11. Which term describes different forms of a gene located
fertilization or implantation. These oral pills effectively
at the same locus on homologous chromosomes?
(A) Alleles

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(B) Linkage groups 3. Initiation codon recognized

(C) Chromatids 4. Peptide bond formation
(D) Mutons 5. Translocation


Ans (A) 3-1-2-4-5
(B) 1-3-2-5-4
(A) Alleles (C) 1-2-3-4-5
Alleles are alternate versions of a gene at the same (D) 3-2-1-4-5
genetic locus on homologous chromosomes. They code
for variations in the same trait, such as flower color. An

Ans
individual inherits one allele from each parent. Different (A) 3-1-2-4-5
allele combinations can produce different phenotypes, First, the initiation codon on mRNA is recognized, then
forming the basis for genetic diversity and inheritance. mRNA attaches to the ribosome. Next, the appropriate
aminoacyl-tRNA binds, allowing peptide bond
12. Why does incomplete dominance in snapdragons formation. Finally, ribosomal translocation moves the
produce a pink phenotype in heterozygotes? ribosome along mRNA. This sequence ensures correct
(A) One allele is completely suppressed polypeptide assembly, strictly reflecting the orderly
(B) Both alleles are equally expressed steps required in translation’s initiation, elongation, and
(C) The dominant allele is only partially expressed termination phases.
(D) The recessive allele outcompetes the dominant
allele 15. Which enzyme catalyzes the unwinding of the DNA


Ans double helix during replication?
(A) DNA polymerase
(C) The dominant allele is only partially expressed (B) DNA helicase
In incomplete dominance, a dominant allele (C) DNA ligase
cannot fully mask the recessive one, resulting in (D) Topoisomerase
an intermediate phenotype. In snapdragons, red
(dominant) allele expression is diluted, producing a

Ans
pink color in heterozygotes. Neither allele achieves (B) DNA helicase
complete phenotypic dominance, truly illustrating how DNA helicase unwinds the double helix by breaking
partial expression leads to a blended appearance in the hydrogen bonds between complementary bases, creating
offspring. two single-stranded templates. DNA polymerase then
synthesizes new strands using these templates. DNA
13. Which is NOT a Mendelian disorder? ligase joins Okazaki fragments, while topoisomerase
(A) Sickle cell anemia relieves supercoiling tension. Helicase’s role is highly
(B) Hemophilia crucial for the replication fork to progress efficiently
(C) Down’s syndrome along DNA.
(D) Thalassemia
16. What is the function of the anticodon loop in tRNA?


Ans
(A) It forms a polypeptide chain
(C) Down’s syndrome (B) It recognizes mRNA codons
Mendelian disorders, like sickle cell anemia, hemophilia, (C) It splices introns from mRNA
and thalassemia, typically result from mutations in (D) It binds ribosomal subunits together
single genes. By contrast, Down’s syndrome arises from
a chromosomal abnormality (trisomy 21) rather than

Ans
a single-gene mutation. This extra chromosome leads (B) It recognizes mRNA codons
to distinct clinical features, quite significantly further The tRNA anticodon loop contains three nucleotides
distinguishing it from classic Mendelian inheritance complementary to the mRNA codon, ensuring the
patterns. correct amino acid is incorporated into the growing
polypeptide. This specificity underlies the fidelity of
14. Arrange the following events of protein synthesis in translation, linking each codon to its corresponding
correct chronological order: amino acid. Introns are spliced from pre-mRNA, and
1. mRNA attaches to ribosome ribosomal subunits bind independently of tRNA.
2. Aminoacyl-tRNA binds

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 PRACTICE PAPER 13

17. Match the following with their primary role in gene 4. Genetic drift
regulation: 5. Parthenogenesis
(A) 1, 2, and 4
Column I Column II
(B) 2, 3, and 5
1. Promoter A. Binds to operator to inhibit (C) 1, 4, and 5
transcription (D) 1, 3, and 5
2. Repressor B. Segment of DNA recognized


Ans
by RNA polymerase
3. Operator C. Region where repressor binds (A) 1, 2, and 4
Modern synthetic theory emphasizes gene mutations
4. Inducer D. Molecule that inactivates
as the source of variation, natural selection as the
repressor
directional force filtering these variations, and
Options: genetic drift as random fluctuations influencing allele
(A) 1-A, 2-B, 3-C, 4-D frequencies. Polyembryony and parthenogenesis
(B) 1-B, 2-A, 3-C, 4-D involve specific reproductive phenomena, but they do
(C) 1-C, 2-D, 3-B, 4-A not universally shape population-level evolutionary
(D) 1-D, 2-C, 3-A, 4-B change as strongly as those three factors.


Ans
20. Why does the Hardy-Weinberg principle require a large
(B) 1-B, 2-A, 3-C, 4-D population size?
A promoter (1) is a DNA region recognized by RNA (A) Large populations mutate slower
polymerase (B). A repressor (2) binds to the operator, (B) Random mating cannot happen in small groups
blocking transcription (A). The operator (3) is the DNA (C) Sampling error is minimized in large populations
segment where the repressor attaches (C). An inducer (D) Allele frequencies do not exist in small populations
(4) inactivates the repressor, thus enabling expression


Ans
(D) and promoting required genes when needed.
(C) Sampling error is minimized in large populations
18. Which statement differentiates natural selection from The Hardy-Weinberg principle assumes large population
genetic drift? size to minimize fluctuations in allele frequencies that
(A) Only genetic drift increases genetic variation could distort equilibrium. Smaller populations are
(B) Genetic drift is caused by selective pressures prone to genetic drift, causing greater deviations from
(C) Natural selection is non-random, while genetic predicted proportions. By reducing sampling errors,
drift is random a large population ensures that allele and genotype
(D) Natural selection never affects large populations frequencies remain stable if other conditions are met.


Ans
21. Which preventive measure best reduces vector-borne
(C) Natural selection is non-random, while genetic drift infections like malaria and dengue?
is random (A) Drinking boiled water
Natural selection favors individuals with advantageous (B) Using bed nets and eliminating stagnant water
traits, truly a non-random process driven by (C) Consuming vitamin supplements
environmental pressures. Genetic drift involves random (D) Undergoing regular blood tests
fluctuations in allele frequencies due to chance events,


Ans
especially in small populations. Selection systematically
shapes adaptation, while drift may increase or decrease (B) Using bed nets and eliminating stagnant water
certain alleles unpredictably, independent of trait Malaria and dengue are transmitted by mosquitoes
benefits or disadvantages. breeding in standing water. Removing stagnant water
sources and using mosquito nets or repellents disrupts
19. Which set of factors primarily drives evolution the insects’ life cycle and reduces contact with humans.
according to modern synthetic theory? Boiled water prevents waterborne diseases; vitamins
1. Gene mutation bolster health but not specifically against mosquito
2. Natural selection transmission, and blood tests detect infection.
3. Polyembryony

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22. Assertion (A) : AIDS results from infection by HIV, a (B) 1-C, 2-D, 3-A, 4-B
retrovirus. (C) 1-B, 2-C, 3-D, 4-A
Reason (R) : Retroviruses do not integrate their genetic (D) 1-A, 2-B, 3-C, 4-D
material into the host genome.

Ans
(A) Both Assertion and Reason are true, and Reason is
the correct explanation. (A) 1-D, 2-C, 3-A, 4-B
(B) Both Assertion and Reason are true, but Reason is Saccharomyces cerevisiae (1) is the common yeast used
not the correct explanation. in baking and brewing (D). Penicillium notatum (2)
(C) Assertion is true, but Reason is false. produces the antibiotic penicillin (C). Methanobacterium
(D) Assertion is false, but Reason is true. (3) helps produce biogas (A) by breaking down organic
matter anaerobically. Lactobacillus (4) ferments lactose


Ans in milk, very effectively aiding curd formation (B)
(C) Assertion is true, but Reason is false through ongoing lactic acid production.
HIV is a retrovirus causing AIDS by infecting and
25. Why are certain bacteria referred to as biofertilizers?
destroying immune cells. Retroviruses like HIV
reverse-transcribe their RNA into DNA, very effectively (A) They directly kill pests on crops
integrating into the host’s genome. Thus, the assertion (B) They degrade all plastics in soil
that HIV causes AIDS is correct, but the reason is false (C) They fix or mobilize essential nutrients for plants
because retroviruses do indeed fully integrate their (D) They generate high-quality compost without
genetic material. microorganisms


Ans
23. Which type of immunity is gained by vaccination with
weakened pathogens? (C) They fix or mobilize essential nutrients for plants
(A) Natural active immunity Biofertilizers involve microorganisms that enrich soil
(B) Artificial active immunity fertility by fixing atmospheric nitrogen, solubilizing
(C) Natural passive immunity phosphorus, or otherwise making nutrients available
(D) Artificial passive immunity to plants. Common examples include Rhizobium
in legume nodules and mycorrhizal fungi assisting


Ans nutrient uptake. By enhancing plant growth naturally,
(B) Artificial active immunity biofertilizers reduce reliance on chemical inputs, thereby
Artificial active immunity develops when an individual effectively promoting truly sustainable agriculture.
is deliberately exposed to weakened or killed pathogens
26. Which of the following microbes does NOT help in
via vaccination. The immune system responds by
producing antibodies and memory cells, thus providing sewage treatment?
long-lasting protection. Natural immunity occurs (A) Methanogenic bacteria
through infection or maternal antibodies, while passive (B) Activated sludge bacteria
immunity involves transfer of ready-made antibodies, (C) Fungal mycelia for secondary treatment
not active generation. (D) Pathogenic E. coli strains


Ans
24. Match each microbe with its primary industrial
application: (D) Pathogenic E. coli strains
Sewage treatment relies on microbes that break down
Column I Column II organic matter in primary, secondary, and anaerobic
1. Saccharomyces A. Biogas production digestion stages. Methanogenic bacteria and many
cerevisiae bacterial or fungal communities help degrade waste.
2. Penicillium B. Curd formation However, pathogenic E. coli strains threaten public
notatum health and do not assist waste decomposition; they
3. Methanobacterium C. Antibiotic production require removal, not utilization, in treatment processes.
4. Lactobacillus D. Baking and brewing 27. Which combination of steps is essential in recombinant
Options: DNA technology?
(A) 1-D, 2-C, 3-A, 4-B 1. Isolation of DNA
2. Tying the DNA ends with ligatures

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 PRACTICE PAPER 13

3. Using restriction endonucleases (A) GM crops are never disease-resistant

4. Ligation of DNA fragments (B) GM crops are produced through conventional
5. Amplification using PCR crossbreeding
(A) 1, 3, 4, 5 (C) GM crops involve specific gene manipulations
(B) 1, 2, 3, 5 (D) GM crops only grow in greenhouses
(C) 2, 4, 5

Ans
(D) 3, 4, 5
(C) GM crops involve specific gene manipulations


Ans Genetically modified crops are created by introducing,
(A) 1, 3, 4, 5 modifying, or silencing specific genes using recombinant
Recombinant DNA technology involves isolating DNA DNA techniques. Traditional breeding relies on crossing
(1), cutting it with restriction endonucleases (3), ligating plants with desirable traits over multiple generations.
the resulting fragments into a vector (4), and amplifying GM approaches precisely target genes for disease
the construct, often by PCR (5). Merely tying DNA ends resistance, stress tolerance, or improved nutrition, thus
with ligatures (2) is not a standard procedure, so options greatly accelerating crop improvement compared to
1, 3, 4, and 5 are correct. conventional methods.

28. What is the role of “sticky ends” generated by restriction 31. Which of the following is NOT an application of
enzymes in genetic engineering? biotechnology in medicine?
(A) They prevent plasmid replication (A) Gene therapy
(B) They facilitate complementary base pairing (B) Stem cell technology
(C) They degrade foreign DNA (C) Antibiotic production
(D) They induce spontaneous mutations (D) Telepathic treatment


Ans

Ans
(B) They facilitate complementary base pairing (D) Telepathic treatment
Sticky ends are overhanging single-stranded segments Biotechnological advances in medicine include gene
formed when restriction enzymes make staggered cuts therapy for genetic disorders, stem cell technology for
in DNA. These ends can anneal with complementary regenerative treatments, and antibiotic production using
sequences from other DNA fragments cut by the same engineered microorganisms. Telepathic treatment,
enzyme. This alignment ensures stable joining of vector lacking valid scientific basis or use of biological systems,
and insert DNA, a key step in forming recombinant does not fall under biotechnological applications.
molecules for cloning. Hence, it is not an established biotechnology-based
approach in medical practice.
29. Which enzyme is used to synthesize cDNA from
mRNA? 32. Match the following with their role in biotech
(A) Restriction endonuclease applications:
(B) Taq polymerase
Column I Column II
(C) Reverse transcriptase
(D) DNA polymerase III 1. Bt toxin gene A. Gene therapy vector
2. Ti plasmid B. Genetically engineered to


Ans
contain beta-carotene
(C) Reverse transcriptase 3. Adenovirus C. Biological insect control
Reverse transcriptase synthesizes complementary DNA vector
(cDNA) from an mRNA template, a very crucial step
4. Golden rice D. Vector from Agrobacterium
in creating eukaryotic gene libraries free of introns.
tumefaciens
Restriction endonucleases cut DNA at specific sites,
Taq polymerase amplifies DNA in PCR, and DNA Options:
polymerase III extends primers during replication. Only (A) 1-C, 2-D, 3-A, 4-B
reverse transcriptase converts RNA into DNA. (B) 1-D, 2-C, 3-B, 4-A
(C) 1-B, 2-A, 3-D, 4-C
30. How do genetically modified (GM) crops differ from (D) 1-A, 2-B, 3-C, 4-D
traditionally bred crops?

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Ans (C) 2, 4, 5
(A) 1-C, 2-D, 3-A, 4-B (D) 1, 3, 4
The Bt toxin gene (1) provides biological insect control

Ans
(C). The Ti plasmid (2) from Agrobacterium tumefaciens
(B) 1, 2, 3, 5
(D) is used as a vector to introduce genes into plants.
Population size changes result from births (1), deaths
Adenovirus (3) serves as a common gene therapy
(2), emigration (3), and immigration (5). Births and
vector (A). Golden rice (4) is genetically engineered for
immigration increase population size, while deaths and
enhanced beta-carotene content (B) successfully.
emigration decrease it. Biomagnification (4) concerns
33. Why is mutualism beneficial for both species involved? pollutant concentration along food chains, not a direct
(A) Both species aggressively compete for resources factor altering population numbers, making 1, 2, 3, and
(B) One species benefits, while the other is unaffected 5 the correct combination.
(C) Each species gains a resource or advantage
36. Arrange the steps of energy flow in the correct sequence:
(D) It reduces biodiversity in the ecosystem
1. Herbivores consume plants


Ans 2. Plants capture sunlight
(C) Each species gains a resource or advantage 3. Primary carnivores eat herbivores
Mutualism describes an interaction where both 4. Secondary carnivores eat primary carnivores
species derive benefits, such as nutrients, protection, (A) 2-1-3-4
or pollination services. Each organism contributes (B) 1-2-3-4
a service or resource the other lacks, creating a net (C) 3-4-1-2
positive outcome for both parties. This cooperation (D) 2-3-1-4
fosters survival and reproductive success, thereby

Ans
enhancing ecological stability, biodiversity, and overall
(A) 2-1-3-4
ecosystem resilience.
Producers (plants) first capture solar energy (2).
34. Which demographic parameter is defined as the number Herbivores then consume plants (1), transferring energy
of individuals born per unit time in a population? up the food chain. Primary carnivores feed on herbivores
(A) Birth rate (3), and secondary carnivores consume the primary
(B) Death rate carnivores (4). This linear sequence demonstrates the
(C) Growth rate very typical, fundamental path of energy flow through
(D) Age distribution trophic levels in an ecosystem.


Ans 37. Why is the energy transfer from one trophic level to the
(A) Birth rate next inefficient?
Birth rate measures the frequency of new individuals (A) All energy is converted to biomass
entering a population through reproduction over a (B) Some energy is lost as heat and waste
specified period. It is often expressed as births per (C) Producers use no energy
thousand individuals annually. Death rate tracks losses (D) Consumers always store 90% of energy
from mortality, while growth rate reflects net change.

Ans
Age distribution shows how individuals are spread
(B) Some energy is lost as heat and waste
across different age classes.
Only a fraction of the energy assimilated by one trophic
35. Which combination of factors directly influences level is passed to the next, with much lost as heat during
population size changes? metabolism and excreted waste. Consequently, biomass
1. Birth rate and energy availability diminish at higher trophic levels.
2. Death rate This inefficiency underlies ecological pyramids and
3. Emigration limits the number of trophic levels in ecosystems.
4. Biomagnification
38. How do pyramids of biomass differ from pyramids of
5. Immigration
energy?
(A) 1, 2, 4
(A) Biomass pyramids always remain upright
(B) 1, 2, 3, 5
(B) Energy pyramids can be inverted

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 PRACTICE PAPER 13

(C) Biomass pyramids represent stored organic matter,

Direction :Carefully read the case study provided and then
while energy pyramids show energy flow rates thoroughly answer the subsequent five questions.
(D) There is no difference between them In a rural region known for its diverse wildlife, a farmer


Ans noticed declining pollinators and soil fertility. Determined
to reverse the trend, she integrated organic farming
(C) Biomass pyramids represent stored organic matter, techniques, avoided chemical pesticides, and planted
while energy pyramids show energy flow rates flowering hedgerows to attract beneficial insects. She
Biomass pyramids illustrate the total dry weight (or also adopted a rotational cropping system with nitrogen-
mass) of organisms at each trophic level at a given time. fixing legumes and engaged in local seed exchange
Energy pyramids depict the flow of energy through programs to preserve indigenous varieties. Furthermore,
trophic levels per unit area per unit time, always upright she set aside wetland patches to nurture amphibians
because energy diminishes upward. Biomass pyramids and aquatic organisms, significantly boosting ecological
can sometimes appear inverted, unlike energy pyramids. balance. Community awareness sessions on pollinator
39. Which of the following does NOT enhance biodiversity conservation and habitat restoration supported her
conservation? efforts. These combined initiatives greatly improved crop
(A) Sacred groves yield and supported local pollinator species like bees and
(B) Wildlife sanctuaries butterflies. Over time, the farmer observed balanced pest
(C) Biopiracy populations, healthier soil, and increased biodiversity on
(D) Biosphere reserves her land, illustrating how sustainable practices can protect
ecosystems while maintaining agricultural productivity.


Ans
41. Which method did the farmer use to maintain soil
(C) Biopiracy
Biodiversity conservation benefits from protected areas fertility?
like sacred groves, wildlife sanctuaries, and biosphere (A) Monoculture
reserves that safeguard habitats and species. Biopiracy, (B) Rotational cropping with legumes
however, involves exploiting biological resources or (C) Heavy pesticide application
traditional knowledge without proper authorization (D) Complete reliance on synthetic fertilizers
or benefit-sharing, greatly undermining conservation

Ans
efforts. Thus, it does not contribute to preserving (B) Rotational cropping with legumes
biodiversity or promoting equitable resource use. The farmer employed rotational cropping with nitrogen-
40. Which strategy best addresses the loss of biodiversity? fixing legumes, a practice that naturally enriches the
(A) Widespread monoculture farming soil. Leguminous plants harbor symbiotic bacteria in
(B) Strict hunting policies without habitat preservation their root nodules, converting atmospheric nitrogen
(C) Habitat protection, legal regulations, and awareness into bioavailable forms. This reduces dependence
programs on synthetic fertilizers, helps sustain soil structure,
(D) Eliminating local seed varieties and supports healthier crop growth, thereby greatly
benefiting multiple cropping seasons.


Ans
42. Why did planting flowering hedgerows benefit the farm?
(C) Habitat protection, legal regulations, and awareness
programs (A) They blocked all sunlight
Comprehensive biodiversity conservation involves (B) They released harmful chemicals
safeguarding habitats, enforcing protective legislation (C) They attracted beneficial insects
against overexploitation, and raising public awareness. (D) They reduced pollination
Monoculture reduces genetic variation; simply

Ans
banning hunting without preserving ecosystems is (C) They attracted beneficial insects
insufficient; eliminating local seed varieties diminishes Flowering hedgerows offer nectar and pollen, inviting
genetic diversity. Hence, a holistic approach uniting helpful insects like pollinators and predators of crop
habitat conservation, legal frameworks, and education pests. These beneficial insects assist in transferring
ultimately yields the best outcomes. pollen among blooms, significantly improving yields,
and controlling pest populations naturally. By fostering

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ecological balance, the hedgerows reduce chemical Sustainable methods like crop rotation, wetland
pesticide use while supporting biodiversity and overall conservation, and reduced chemical inputs create
farm health. harmonious ecological conditions. Beneficial organisms
thrive, regulating pest species, while soil fertility
43. Which action mentioned did NOT help enhance improves through natural nutrient cycles. This synergy
biodiversity? leads to a more diverse array of flora and fauna,
(A) Planting flowering hedgerows significantly stabilizing yields and reinforcing overall
(B) Protecting wetland patches farm ecosystem health.
(C) Using local seed exchange programs
(D) Heavy use of chemical pesticides

Direction :Carefully read the case study provided and then


Ans thoroughly answer the subsequent five questions.
In a family with a history of thalassemia, a young couple
(D) Heavy use of chemical pesticides decided to seek genetic counseling before planning a
Chemical pesticides very often harm non-target child. The counselor explained that thalassemia follows
organisms, reduce beneficial insect populations, and a Mendelian pattern, often requiring both parents to
contaminate soil and water. They disrupt natural carry a mutated gene. By conducting a simple blood
ecological balance, curbing biodiversity gains. test and analyzing their hemoglobin profiles, medical
Conversely, practices like flowering hedgerows, wetland experts identified them as carriers. Understanding the
conservation, and local seed exchange encourage risks, the couple explored reproductive options such as
beneficial species, conserve habitats, and maintain prenatal diagnosis and genetic testing. They learned
genetic diversity, thereby significantly improving overall about advanced reproductive technologies like IVF
ecosystem health. combined with pre-implantation genetic testing to
44. How does preserving local seed varieties promote ensure an unaffected embryo. Although these techniques
biodiversity? involved ethical and financial considerations, the couple
(A) It introduces invasive species recognized the importance of informed decision-making
(B) It eliminates natural predators to mitigate inherited disease burdens. Ultimately, they
(C) It maintains genetic diversity in crops aimed to prevent passing on the disorder and promote
(D) It increases pesticide usage overall family health, illustrating how modern genetics
can empower individuals.


Ans
46. Which genetic pattern does thalassemia typically follow?
(C) It maintains genetic diversity in crops
Local or indigenous seed varieties carry region-specific (A) Polygenic inheritance
traits, including resistance to local pests, diseases, (B) Chromosomal aneuploidy
and climate conditions. Preserving these seeds fosters (C) Mendelian inheritance
genetic variability within crop populations, reducing (D) Cytoplasmic inheritance
vulnerability to environmental pressures. This diversity

Ans
underpins stable yields, ecosystem resilience, and the (C) Mendelian inheritance
capacity to continually adapt to evolving threats or Thalassemia usually results from mutations in a single
changing conditions. gene affecting hemoglobin production. This fully aligns
45. Which overarching outcome did the farmer witness with Mendelian inheritance, wherein a child inherits two
after implementing sustainable practices? gene copies, one from each parent. When both parents
(A) Reduced soil health and fewer pollinators carry the mutant allele, offspring risk manifesting the
(B) Declining pest control and ecosystem imbalance disorder or being carriers, depending on the specific
(C) Balanced pest populations, healthier soil, and inheritance pattern.
richer biodiversity 47. Which diagnostic method helped identify the couple as
(D) Complete elimination of insects from the farm thalassemia carriers?


Ans (A) Karyotyping
(C) Balanced pest populations, healthier soil, and richer (B) Hemoglobin profile analysis
biodiversity (C) Amniocentesis
(D) Ultrasound imaging

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 PRACTICE PAPER 13

Ans 50. What was the couple’s primary motivation for exploring
(B) Hemoglobin profile analysis advanced reproductive technologies?
Hemoglobin profiling evaluates hemoglobin variants (A) Curiosity about new technology
and identifies abnormalities, revealing carrier status (B) Desire to ensure an unaffected offspring
for conditions like thalassemia. Karyotyping detects (C) Interest in genetically enhancing traits
chromosomal changes, whereas amniocentesis and (D) Wish to avoid medical procedures
ultrasound are prenatal procedures. By analyzing

Ans
hemoglobin chains and ratios, doctors confirm whether
(B) Desire to ensure an unaffected offspring
individuals carry the defective gene responsible for
They sought to fully prevent transmitting thalassemia,
reduced or altered hemoglobin synthesis, confirming
a serious inherited genetic disorder, to their child. By
carrier status.
investigating advanced techniques like IVF with pre-
48. Assertion (A) : IVF with pre-implantation genetic implantation genetic testing, they could screen embryos
testing can prevent inheriting certain genetic disorders. for the mutation before implantation. This approach
Reason (R) : Pre-implantation testing screens embryos directly targets the hereditary risk, aligning with their
for mutations before implantation. goal of a healthy, unaffected child.
(A) Both Assertion and Reason are true, and Reason is


*************
the correct explanation.
(B) Both Assertion and Reason are true, but Reason is
not the correct explanation.
(C) Assertion is true, but Reason is false.
(D) Assertion is false, but Reason is true.


Ans
(A) Both Assertion and Reason are true, and Reason is
the correct explanation
Pre-implantation genetic testing examines embryos
conceived via IVF for specific mutations before transfer
to the uterus. By selecting healthy embryos, the risk of
passing on the disorder is seriously minimized. Thus, the
assertion is true, and the reason accurately explains how
embryo screening helps prevent inherited conditions in
at-risk couples.

49. Which procedure does NOT directly apply to preventing

thalassemia transmission?
(A) Prenatal diagnosis
(B) Genetic counseling
(C) Ultrasound for fetal imaging
(D) Pre-implantation genetic testing


Ans
(C) Ultrasound for fetal imaging
Ultrasound imaging primarily checks fetal growth,
structural anatomy, and viability but does not detect
specific genetic mutations causing thalassemia. In
contrast, prenatal diagnosis (chorionic villus sampling
or amniocentesis), genetic counseling, and pre-
implantation genetic testing directly address the
disorder’s inheritance risk. Ultrasound alone cannot
actively prevent or fully diagnose carrier status.

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PRACTICE PAPER 14

1. Which structure in the ovule ultimately develops into pollen tube, delivering sperm cells to the ovule. Non-
the seed coat? viable pollen either fails to hydrate or cannot extend a
(A) Nucellus pollen tube, disrupting fertilization. Maintaining pollen
(B) Integuments viability increases the likelihood of successful seed and
(C) Micropyle fruit set.
(D) Embryo sac
4. Which hormone triggers ovulation around the midpoint


Ans of the menstrual cycle?
(B) Integuments (A) Follicle-stimulating hormone (FSH)
Integuments are the protective layers surrounding (B) Luteinizing hormone (LH)
the ovule; after fertilization, they typically harden and (C) Prolactin
transform into the seed coat. The nucellus supplies (D) Oxytocin
nutrients and may persist or degenerate, while the

Ans
micropyle remains as a small pore. The embryo sac
houses the female gametophyte but does not form the (B) Luteinizing hormone (LH)
seed coat. A surge in luteinizing hormone (LH) around day 14
in a typical 28-day cycle induces ovulation, releasing
2. Which term describes the fusion of two male gametes the secondary oocyte from the dominant follicle.
with two different cells in the embryo sac? FSH promotes follicular growth, prolactin aids
(A) Triple fusion milk production, and oxytocin stimulates uterine
(B) Double fertilization contractions and milk ejection but does not initiate
(C) Pollination ovulation.
(D) Parthenocarpy
5. Which is NOT a function of the female reproductive


Ans system’s oviducts (fallopian tubes)?
(B) Double fertilization (A) Site of fertilization
Double fertilization in flowering plants involves one (B) Conduit for sperm to meet ovum
male gamete fusing with the egg, forming the zygote, (C) Implantation of the embryo
and the other male gamete fusing with the central (D) Transport of fertilized ovum to uterus
cell to create the endosperm. This process is unique

Ans
to angiosperms, ensuring simultaneous embryo and
endosperm formation. Triple fusion refers specifically (C) Implantation of the embryo
to the fusion producing endosperm. The fallopian tubes guide the ovum, allow fertilization in
the ampullary region, and transport the fertilized ovum
3. Why does pollen viability matter for successful toward the uterus. Implantation, however, occurs in the
fertilization? uterine endometrium, not in the tubes. Thus, the oviduct
(A) Non-viable pollen reduces seed size facilitates fertilization and early embryo movement but
(B) Viable pollen can germinate and form a pollen tube does not support embryonic implantation.
(C) Viable pollen always self-pollinates
6. Which structure in the testes produces sperm?
(D) Non-viable pollen is required for cross-breeding
(A) Leydig cells


Ans (B) Sertoli cells
(B) Viable pollen can germinate and form a pollen tube (C) Rete testis
Pollen viability ensures that the male gametophyte (D) Seminiferous tubules
can germinate on the stigma and form a functional

Ans

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 PRACTICE PAPER 14

(D) Seminiferous tubules (B) Both Assertion and Reason are true, but Reason is
Seminiferous tubules are the specific sites where not the correct explanation.
spermatogenesis occurs, producing mature sperm cells. (C) Assertion is true, but Reason is false.
Sertoli cells within these tubules support developing (D) Assertion is false, but Reason is true.
sperm, while Leydig cells secrete testosterone in the

Ans
interstitial spaces. Rete testis is a network collecting
sperm before they move to the epididymis, but not the (C) Assertion is true, but Reason is false
actual site of sperm production. Amniocentesis extracts and analyzes amniotic fluid
for fetal cells, revealing chromosomal or metabolic
7. Which strategy is most effective for preventing sexually disorders. While it helps diagnose conditions like
transmitted diseases (STDs)? Down’s syndrome, it does not cure them. Identifying a
(A) Periodic ultrasound scans disorder guides prospective parents and clinicians but
(B) Maintaining complete personal hygiene and using does not offer a direct therapeutic intervention for the
protection fetus.
(C) Consuming high-protein diets
10. How does codominance differ from incomplete
(D) Engaging only in polygamous relationships
dominance?


Ans (A) In codominance, neither allele is expressed
(B) Maintaining complete personal hygiene and using (B) In incomplete dominance, both alleles are fully
protection expressed
STD prevention primarily relies on safe sexual practices, (C) In codominance, both alleles are fully expressed
such as consistent use of condoms and proper personal without blending
hygiene. Regular health checkups and communication (D) There is no difference
with partners further reduce transmission risks.

Ans
Diet and ultrasound scans do not prevent STDs, and
polygamous relationships without protection elevate (C) In codominance, both alleles are fully expressed
the risk rather than mitigate it. without blending
In codominance, each allele in a heterozygote expresses
8. Which technique involves fertilizing an ovum outside distinctly (e.g., AB blood group), while incomplete
the body and then transferring the embryo to the uterus? dominance produces an intermediate phenotype (e.g.,
(A) GIFT pink flowers from red and white alleles). Both processes
(B) IVF-ET deviate from classic dominance, but only codominance
(C) IUI shows simultaneous, full expression of both alleles.
(D) MTP
11. Which genotype will express the dominant trait in


Ans incomplete dominance?
(B) IVF-ET (A) Only homozygous dominant
In Vitro Fertilization and Embryo Transfer (IVF-ET) (B) Only homozygous recessive
entails collecting ova from the ovary, fertilizing them (C) Both homozygous dominant and heterozygous, but
externally with sperm, and transferring the resulting with different phenotypes
embryo into the uterus. GIFT (Gamete Intra-Fallopian (D) Only heterozygous
Transfer) places gametes in the fallopian tube, IUI

Ans
(Intrauterine Insemination) deposits sperm in the
uterus, and MTP stands for medical termination of (C) Both homozygous dominant and heterozygous, but
pregnancy. with different phenotypes
In incomplete dominance, the homozygous dominant
9. Assertion (A) : Amniocentesis is used to identify genotype exhibits the full dominant phenotype, while
chromosomal abnormalities in the fetus. the heterozygous genotype shows an intermediate
Reason (R) : Amniocentesis directly cures genetic phenotype. Homozygous recessive expresses the
diseases in the fetus. recessive trait. Thus, both homozygous dominant and
(A) Both Assertion and Reason are true, and Reason is heterozygous individuals display a “dominant” trait,
the correct explanation.

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page 138 CUET UG Biology

though the heterozygote’s phenotype is partially reduced processing. Only the structural gene portion directly
or blended. translates into a protein.

12. Which of the following is NOT typically inherited via 15. Which component carries amino acids to the ribosome
sex-linked recessive genes in humans? during translation?
(A) Hemophilia (A) mRNA
(B) Red-green color blindness (B) tRNA
(C) Sickle cell anemia (C) rRNA
(D) Duchenne muscular dystrophy (D) snRNA


Ans

Ans
(C) Sickle cell anemia (B) tRNA
Hemophilia, red-green color blindness, and Duchenne Transfer RNA (tRNA) molecules attach to specific
muscular dystrophy often follow an X-linked recessive amino acids and present anticodons complementary
pattern, more commonly affecting males. Sickle to mRNA codons at the ribosome. Messenger RNA
cell anemia, however, is an autosomal recessive (mRNA) provides the codon sequence, ribosomal RNA
condition involving a mutation in the beta-globin (rRNA) forms the core ribosome structure, and snRNA
gene on chromosome 11, not inherited through the X aids in splicing. Thus, tRNA delivers amino acids for
chromosome. polypeptide synthesis.

13. Assertion (A) : Males determine the sex of the child in 16. Why is the lac operon induced in the presence of lactose?
humans. (A) Lactose mutates the repressor
Reason (R) : A female’s gametes carry only an X (B) Lactose acts as an inducer, binding the repressor
chromosome, while male gametes can be X or Y. (C) Glucose directly inhibits mRNA synthesis
(A) Both Assertion and Reason are true, and Reason is (D) The structural genes are always turned on
the correct explanation.

Ans
(B) Both Assertion and Reason are true, but Reason is
not the correct explanation. (B) Lactose acts as an inducer, binding the repressor
(C) Assertion is true, but Reason is false. In the lac operon, lactose (or allolactose) binds to the
(D) Assertion is false, but Reason is true. repressor protein, altering its conformation so it can no
longer bind the operator. This frees RNA polymerase


Ans to transcribe the operon’s genes, enabling lactose
(A) Both Assertion and Reason are true, and Reason is metabolism. Without lactose, the repressor stays bound,
the correct explanation preventing gene expression.
Female gametes invariably contain an X chromosome,
17. Which combination of processes leads to RNA synthesis
while male gametes can have either X or Y. If a Y-carrying
sperm fertilizes the ovum, a male (XY) results. If an and subsequent protein formation?
X-bearing sperm fertilizes it, a female (XX) forms. Thus, 1. Replication
the male’s gamete decides the offspring’s sex. 2. Transcription
3. Translation
14. Which segment of DNA codes for a polypeptide? 4. Reverse transcription
(A) Promoter 5. Splicing
(B) Operon (A) 1, 4, and 5
(C) Structural gene (B) 2, 3, and 5
(D) Introns (C) 2, 4, and 5


Ans (D) 1, 2, and 3

(C) Structural gene

Ans

A structural gene is the specific DNA segment that (B) 2, 3, and 5
encodes a polypeptide. Promoters regulate where Genes are transcribed (2) into pre-mRNA, which
transcription begins, operons are functional units often undergoes splicing (5) to remove introns. The
containing structural genes plus regulatory regions, and mature mRNA is then translated (3) into a polypeptide.
introns are noncoding segments removed during RNA Replication (1) duplicates DNA, and reverse

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 PRACTICE PAPER 14

transcription (4) synthesizes DNA from RNA but is not 21. Which pathogen type causes amoebiasis?
part of typical gene expression in eukaryotes. (A) Bacterium
(B) Virus
18. Which scientist is credited with proposing the theory of (C) Protozoan
natural selection in tandem with Charles Darwin? (D) Fungus
(A) Alfred Russel Wallace
(B) Gregor Mendel

Ans
(C) Jean-Baptiste Lamarck (C) Protozoan
(D) Thomas Malthus Amoebiasis is primarily caused by the protozoan


Ans Entamoeba histolytica. Bacterial pathogens cause
diseases like pneumonia and typhoid, while viruses
(A) Alfred Russel Wallace cause ailments like the common cold and dengue.
Alfred Russel Wallace independently conceived the idea Fungal pathogens lead to ringworm infections, but
of evolution by natural selection and corresponded with amoebiasis originates from a protozoan parasite.
Darwin. Their combined insights prompted Darwin
to publish “On the Origin of Species.” Mendel laid 22. Which disease is characterized by malignant growth
foundations of genetics, Lamarck proposed inheritance due to uncontrolled cell division?
of acquired traits, and Malthus influenced Darwin’s (A) Tuberculosis
thinking on population pressure. (B) Cancer
(C) Filariasis
19. Why does mutation fuel the process of evolution? (D) Typhoid
(A) Mutations prevent genetic variation
(B) Mutations reduce survival

Ans
(C) Mutations introduce new alleles (B) Cancer
(D) Mutations maintain all alleles at equilibrium Cancer involves uncontrolled cell division forming


Ans tumors, which may invade surrounding tissues or spread
to distant sites (metastasis). Tuberculosis is a bacterial
(C) Mutations introduce new alleles infection, filariasis is a parasitic disease affecting
Mutations alter the genetic material, creating novel lymphatic vessels, and typhoid is caused by Salmonella
alleles or variations in existing ones. This fresh genetic typhi. Cancer results from genetic and environmental
diversity provides raw material on which natural factors disturbing cell regulation.
selection can act. While some mutations are harmful,
others may confer advantages in certain environments, 23. Which approach best prevents the spread of HIV/AIDS?
thus fueling evolutionary change across generations. (A) Sharing needles among trusted friends
(B) Practice of safe sex, screening blood, and avoiding
20. Which of the following does NOT directly support needle sharing
evolution? (C) Avoiding vaccination programs
(A) Fossil records (D) Self-prescribing antibiotics frequently
(B) Comparative embryology
(C) DNA sequence homology

Ans
(D) Lunar cycle observations (B) Practice of safe sex, screening blood, and avoiding


Ans needle sharing
HIV spreads via unprotected sexual contact,
(D) Lunar cycle observations contaminated blood transfusions, and shared needles.
Evolutionary evidence arises from paleontological Thus, consistent condom use, proper blood screening,
records (fossils), comparative embryology, and and refraining from needle sharing are vital in
molecular data like DNA or protein sequences. These prevention. Antibiotics do not target viruses, and
show relationships among species and ancestral ignoring vaccinations or relying on “trusted” needle
patterns. Lunar cycles relate to moon phases, tides, sharing does not halt HIV transmission.
and behavior patterns in some organisms but do not
demonstrate how species evolve over time. 24. Which set of microbes are useful for industrial
fermentation processes?

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1. Saccharomyces cerevisiae Biofertilizers rely on beneficial microbes like Rhizobium,

2. Penicillium roqueforti Azotobacter, or mycorrhizae to enhance soil fertility.
3. HIV Consistently applying toxic fungicides can kill or
4. Lactobacillus bulgaricus inhibit these helpful microbes, undermining the very
5. Ebola virus purpose of biofertilizers. Hence, employing harmful
(A) 1, 2, and 4 chemicals alongside biofertilizers is counterproductive
(B) 2, 3, and 5 to sustainable, microbe-based soil enrichment.
(C) 1, 4, and 5
27. Arrange these steps in the correct order for producing
(D) 3, 4, and 5
recombinant insulin:


Ans 1. Synthesis of A and B chains separately
(A) 1, 2, and 4 2. Restriction enzyme digestion
Saccharomyces cerevisiae (yeast) is employed in bread, 3. Ligation into plasmid vectors
beer, and wine making; Penicillium roqueforti helps 4. Joining of chains to form functional insulin
in cheese ripening; Lactobacillus bulgaricus ferments 5. Transformation into bacterial host
dairy into yogurt. HIV and Ebola are viruses causing (A) 2-3-5-1-4
severe diseases, not involved in beneficial industrial (B) 2-1-3-5-4
fermentation. (C) 1-2-3-4-5
(D) 2-5-3-1-4
25. Why are Baculoviruses considered beneficial as
biocontrol agents?

Ans
(A) They attack beneficial insects (A) 2-3-5-1-4
(B) They produce antibiotic residues First, the desired DNA fragments are cut by restriction
(C) They specifically target insect pests without enzymes (2), then inserted into plasmids (3). These
harming other organisms recombinant plasmids are transformed into bacterial
(D) They pollute water sources severely hosts (5). Each host separately produces insulin A and B


Ans polypeptide chains (1). Finally, the chains are combined
(4) to form functional human insulin.
(C) They specifically target insect pests without harming
other organisms 28. Why do plasmids serve as effective cloning vectors?
Baculoviruses selectively infect insect pests, especially (A) They are large and hard to manipulate
Lepidopteran larvae, minimizing damage to non- (B) They lack replication origins
target species. This specificity makes them excellent for (C) They often contain selectable markers and replicate
biological pest control, reducing reliance on chemical independently
pesticides that can harm beneficial organisms. Properly (D) They are immune to restriction enzymes
applied, baculoviruses pose minimal environmental

Ans
toxicity and preserve overall biodiversity.
(C) They often contain selectable markers and replicate
26. Which practice does NOT align with the safe use of independently
biofertilizers? Plasmids are small, circular DNA molecules carrying
(A) Employing Rhizobium for legume cultivation their own origin of replication. They typically have
(B) Using mycorrhizal fungi for better phosphate antibiotic resistance genes or other markers for easy
uptake selection of transformed cells, and they replicate
(C) Spraying toxic chemical fungicides regularly with independently of the bacterial chromosome. Their
biofertilizers manageability and selectable features make them
(D) Introducing Azotobacter to increase nitrogen excellent vectors for gene cloning.
content
29. Which crop is commonly engineered with the Bt gene to


Ans protect against insect pests?
(C) Spraying toxic chemical fungicides regularly with (A) Bt Rice
biofertilizers (B) Bt Wheat
(C) Bt Cotton

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 PRACTICE PAPER 14

(D) Bt Soybean

Ans

Ans (C) Predation

Predation involves a predator consuming a prey
(C) Bt Cotton
organism, often causing the prey’s death. Competition
Bt cotton harbors a gene from Bacillus thuringiensis
sees organisms vie for the same resources, mutualism
producing a toxin lethal to certain insect larvae,
benefits both partners, and commensalism benefits
especially bollworms. While research exists for other
one without harming the other. Predation is a direct
Bt-engineered crops, Bt cotton stands as the widely
consumptive interaction driving many ecological
commercialized example. This genetic intervention
adaptations.
significantly reduces pesticide use and crop losses from
bollworm infestation. 33. Assertion (A) : Pyramids of energy in ecosystems can
be inverted.
30. How does gene therapy differ from vaccination?
Reason (R) : Energy decreases at each succeeding
(A) Gene therapy introduces weakened pathogens
trophic level due to losses as heat and waste.
(B) Vaccination corrects existing genetic disorders
(A) Both Assertion and Reason are true, and Reason is
(C) Gene therapy aims to fix or replace faulty genes,
the correct explanation.
while vaccination trains the immune system
(B) Both Assertion and Reason are true, but Reason is
(D) Both are used interchangeably
not the correct explanation.


Ans (C) Assertion is false, but Reason is true.
(C) Gene therapy aims to fix or replace faulty genes, (D) Assertion is true, but Reason is false.
while vaccination trains the immune system

Ans
Vaccines expose the body to antigens—either weakened
(C) Assertion is false, but Reason is true
pathogens or fragments—so the immune system
Energy pyramids are always upright because each level
develops memory and protection. Gene therapy,
receives less energy than the previous one, primarily
however, attempts to rectify or replace a defective gene
due to heat and metabolic losses. Biomass pyramids can
responsible for a disorder. These distinct strategies
sometimes be inverted, but energy cannot accumulate
address different health issues, reflecting separate
going upwards. Thus, the reason is correct, but the
underlying biological principles.
assertion about inverted energy pyramids is false.
31. Which factor most strongly affects the size of a
34. Why is productivity generally higher in tropical regions
population in a stable environment?
compared to polar ones?
(A) Overuse of inorganic fertilizers
(A) Tropical regions have fewer predators
(B) Immigration and emigration
(B) Polar areas receive more sunlight
(C) Random geological events
(C) Warm temperatures and ample rainfall support
(D) Irregular gene expression
abundant plant growth


Ans (D) Tropical latitudes have no decomposers
(B) Immigration and emigration

Ans
In a relatively stable environment, birth and death rates
(C) Warm temperatures and ample rainfall support
often balance out. However, the influx (immigration)
abundant plant growth
or departure (emigration) of individuals can quickly
Tropical areas typically have year-round warmth,
shift population size. Overuse of fertilizers, geological
high moisture availability, and longer growing
events, or gene expression variabilities may influence
seasons, leading to dense vegetation and high primary
populations indirectly but are typically less immediate
productivity. Polar regions have shorter summers, less
than migration changes.
sunlight, and colder climates, limiting plant growth.
32. Which interaction describes an organism feeding on Predators or decomposers do not primarily dictate the
another living organism, usually killing it? fundamental productivity of these ecosystems.
(A) Competition
35. Which activity does NOT promote biodiversity?
(B) Mutualism
(A) Establishing national parks
(C) Predation
(B) Habitat destruction and fragmentation
(D) Commensalism

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(C) Reducing overexploitation of species involvement. The biodiversity hotspot concept was
(D) Preserving genetic diversity in seed banks popularized even more recently. Thus, from oldest to


Ans newest: sacred groves, wildlife sanctuaries, biosphere
reserves, and hotspot identification
(B) Habitat destruction and fragmentation
Habitat destruction and fragmentation severely threaten 38. Assertion (A) : Microbes can be used as bio-control
biodiversity by isolating populations, reducing gene agents to reduce chemical pesticide usage.
flow, and eliminating critical resources. Establishing Reason (R) : Certain bacteria, fungi, and viruses
protected areas, curbing overexploitation, and storing selectively infect pests without harming other organisms.
seeds in banks all safeguard species and genetic variety, (A) Both Assertion and Reason are true, and Reason is
enhancing conservation. Destroying habitats directly the correct explanation.
undermines these conservation efforts. (B) Both Assertion and Reason are true, but Reason is
not the correct explanation.
36. Which combination of conservation strategies is vital (C) Assertion is true, but Reason is false.
for protecting endangered species? (D) Assertion is false, but Reason is true.
1. In-situ conservation (national parks, sanctuaries)
2. Ex-situ conservation (zoos, seed banks)

Ans
3. Monoculture promotion (A) Both Assertion and Reason are true, and Reason is
4. Controlled hunting for profit the correct explanation
5. Community participation and awareness Biological control agents like Bacillus thuringiensis
(A) 1, 2, and 5 produce toxins that target specific insects. This
(B) 1, 3, and 4 selectivity avoids non-target species, reducing the
(C) 2, 4, and 5 ecological and health risks associated with chemical
(D) 3, 4, and 5 pesticides. Hence, the reason directly supports the


Ans assertion, confirming the efficiency of microbes in eco-
friendly pest management. It aligns with sustainable
(A) 1, 2, and 5 agriculture principles
Protecting endangered species typically combines in-
situ measures (1) to preserve habitats, ex-situ methods 39. Match the following ecological terms in Column I with
(2) like zoos or seed banks for critical backup, and their descriptions in Column II:
public engagement (5) promoting sustainable practices.
Column I Column II
Monoculture (3) reduces biodiversity, and hunting
for profit (4) undermines conservation unless tightly a. Detritivores i. Ratio of energy passed from
regulated with specific goals and oversight. one trophic level to another
b. Food chain ii. Sequence of who eats whom
37. Arrange these conservation methods from older to c. Ecological iii. Total dry weight of living
more recent adoption: efficiency organisms
1. Sacred groves
d. Biomass iv. Organisms that feed on
2. Biosphere reserves
dead organic matter
3. Wildlife sanctuaries
4. Biodiversity hotspots concept Options:
(A) 1 → 3 → 2 → 4 (A) a-iv, b-ii, c-i, d-iii
(B) 3 → 1 → 4 → 2 (B) a-ii, b-iv, c-iii, d-i
(C) 1 → 2 → 3 → 4 (C) a-i, b-iii, c-ii, d-iv
(D) 1 → 4 → 3 → 2 (D) a-iii, b-i, c-iv, d-ii


Ans

Ans

(A) 1 → 3 → 2 → 4 (A) a-iv, b-ii, c-i, d-iii

Sacred groves are ancient community traditions. Detritivores consume dead material, food chains
Wildlife sanctuaries emerged under formal conservation describe feeding relationships, ecological efficiency
policies. Biosphere reserves gained traction later, measures energy transfer between trophic levels,
incorporating scientific management and human and biomass is the total dry mass of living entities.

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 PRACTICE PAPER 14

Understanding these concepts helps illustrate ecosystem water’s surface, blocking sunlight, depleting oxygen, and
structure, energy dynamics, and nutrient cycling across outcompeting native flora. This reduces fish populations
various habitats and hinders local livelihoods, making water hyacinth a
prime example of a destructive invasive species.
40. A person with blood group AB exhibits which
inheritance pattern for the ABO locus? 42. How did invasive water hyacinth impact fish
(A) Incomplete dominance populations?
(B) Co-dominance (A) It provided extra food for fish
(C) Complete dominance (B) It increased oxygen levels
(D) Multiple allelism without co-dominance (C) It clogged waterways and reduced oxygen


Ans (D) It solely boosted fishing profits

(B) Co-dominance

Ans

Individuals with blood group AB express both A and (C) It clogged waterways and reduced oxygen
B antigens equally on red blood cells. Neither allele is Water hyacinth grows rapidly, forming thick surface
recessive; both manifest their respective antigens fully. layers that block sunlight penetration, curtailing
This exemplifies co-dominance, in which heterozygotes photosynthesis in submerged plants. This lowers
display phenotypes contributed by both alleles dissolved oxygen, vital for aquatic life. Fish suffer from
simultaneously, reflecting a crucial exception to classical hypoxic conditions and restricted movement through
Mendelian dominance congested channels, leading to reduced populations and
economic impacts on fishing communities.


Direction :Carefully read the case study provided and then
thoroughly answer the subsequent five questions. 43. Which measure did NOT help counter the invasive
A large wetland region, once home to abundant fish and weed problem?
migratory birds, experienced a surge in invasive water (A) Harvesting water hyacinth for compost
hyacinth. This fast-growing aquatic weed competed (B) Introducing native aquatic plants
with native plant species and clogged waterways, (C) Creating handicrafts from hyacinth
reducing oxygen levels and threatening fish populations. (D) Allowing uncontrolled weed expansion
Local communities relied on fishing for livelihood but

Ans
found catches dwindling. In response, conservationists
worked with villagers to harvest water hyacinth for (D) Allowing uncontrolled weed expansion
composting and handicraft making, cutting back its The case mentions methods to control water hyacinth—
spread. Simultaneously, an ecological restoration team harvesting for compost and handicrafts, alongside
introduced native aquatic plants to restore habitat quality. reintroducing native species. Permitting the invasive
By promoting awareness of the wetland’s importance for weed’s unchecked growth worsens clogging and oxygen
bird migration and fish breeding, stakeholders recognized depletion. Therefore, taking no action fails to improve
that sustainable management practices—like regulated wetland health, unlike the other interventions that curb
fishing seasons and weed control—could improve water or repurpose hyacinth.
quality, safeguard biodiversity, and maintain economic 44. Why is regulating fishing seasons beneficial for the
benefits for the local population. wetland community?
41. Which invasive species disrupted the wetland ecosystem (A) It depletes fish stocks faster
in the case study? (B) It allows fish populations to reproduce and recover
(A) Water lettuce (C) It discourages tourism
(B) Water hyacinth (D) It eliminates all predatory fish
(C) Lotus

Ans
(D) Native reeds (B) It allows fish populations to reproduce and recover


Ans Restricting fishing to certain times or seasons ensures
(B) Water hyacinth that key breeding periods are undisturbed, granting fish
The case study explicitly identifies water hyacinth as stocks the chance to spawn and maintain sustainable
the invasive aquatic weed. It forms dense mats on the numbers. Overfishing without regulation leads to
population collapse, but controlled harvesting balances

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economic needs with long-term ecological stability and Traditional culture-based methods were slow, risking
continued community benefits. public health if contaminated milk reached consumers.
Hence, the researchers engineered a bacteriophage with
45. Which outcome exemplifies the success of the wetland a reporter gene to rapidly identify pathogenic bacteria.
restoration efforts?
(A) Complete eradication of all aquatic plants 47. How did the modified bacteriophage indicate bacterial
(B) Higher fish catches, restored habitats, and stable presence?
community livelihoods (A) It destroyed all microorganisms
(C) Banning local involvement in resource use (B) It changed color via a reporter gene
(D) Permanent replacement of wetlands with farmland (C) It halted bacterial metabolism without detection


Ans (D) It produced no visible signal

(B) Higher fish catches, restored habitats, and stable

Ans

community livelihoods (B) It changed color via a reporter gene
Success is seen in balanced ecological restoration that The biotech approach involved inserting a reporter gene
boosts fish populations, maintains bird migration into the phage, yielding a color change when the phage
routes, and secures local economic interests. The case successfully infected target bacteria. This visible signal
highlights improved water quality, weed management, dramatically speeds testing by making contamination
and community cooperation. Eradicating all plants readily apparent. Without a reporter, detection would
or converting wetlands are counterproductive, while remain reliant on slower or more complex measurement
excluding local residents often undermines conservation techniques.
goals.
48. Which factor did NOT favor the adoption of this new


Direction :Carefully read the case study provided and then test?
thoroughly answer the subsequent five questions. (A) Reduced detection time
A biotechnology startup aimed to develop a method to (B) Ability to prevent contaminated milk distribution
detect pathogenic bacteria in milk quickly. Traditional (C) Increased economic losses due to lengthy recalls
culture methods took days, risking public health concerns (D) Biosafety measures ensuring controlled phage
if contaminated batches reached consumers. The scientists release
used a genetically modified bacteriophage carrying a

Ans
reporter gene that produced a visible color change in the
presence of targeted bacterial strains. By engineering this (C) Increased economic losses due to lengthy recalls
phage, the detection window dropped to a few hours. The test actually reduced potential losses by rapidly
Following trials in dairy plants, the rapid test system catching contaminated batches, thus avoiding large-
prevented distribution of tainted milk and reduced scale recalls. Faster detection prevents distribution of
economic losses from widespread recalls. Although there unsafe milk, benefiting public health and saving costs.
were initial debates about releasing genetically modified Proper biosafety controls also address concerns about
phages, strict biosafety protocols and regulatory guidelines using genetically modified phages. Hence, increased
ensured controlled usage. Eventually, this innovative losses do not favor the system.
approach demonstrated how biotechnology can safeguard 49. Assertion: Strict biosafety protocols were implemented
food supplies while minimizing testing delays. for the GM phages.
46. What was the primary goal of the biotechnology startup? Reason: Genetically modified organisms can pose risks
(A) To modify dairy cows genetically if released without regulation.
(B) To produce new flavors in milk (A) Both Assertion and Reason are true, and Reason is
(C) To detect pathogenic bacteria in milk quickly the correct explanation.
(D) To promote manual milk-testing methods (B) Both Assertion and Reason are true, but Reason is
not the correct explanation.


Ans (C) Assertion is true, but Reason is false.
(C) To detect pathogenic bacteria in milk quickly (D) Assertion is false, but Reason is true.
The case explicitly states the startup intended to shorten

Ans
detection times for bacterial contaminants in milk.

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 PRACTICE PAPER 14

(A) Both Assertion and Reason are true, and Reason is

the correct explanation
GM bacteriophages, like other genetically modified
entities, could impact ecosystems if mishandled.
Therefore, strict containment and usage protocols
are essential. The reason accurately explains why the
assertion is valid: regulating GMO releases prevents
unintended environmental effects, justifying the
mandatory biosafety measures for these phages.

50. What core benefit did this rapid phage-based test

provide to the dairy industry?
(A) Eliminated all bacteria in milk
(B) Prevented any future need for regulatory oversight
(C) Significantly shortened detection time and
minimized recall costs
(D) Allowed distribution of contaminated milk without
consequences


Ans
(C) Significantly shortened detection time and
minimized recall costs
By cutting detection windows from days to hours, the
biotech method enabled quicker intervention and
quarantine of tainted batches. This rapid response
limited contaminated milk shipments, reducing large-
scale recalls and protecting public health. It did not
eliminate bacteria outright or bypass regulation but
streamlined safety measures effectively.

*************

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PRACTICE PAPER 15

1. What does the term “double fertilization” specifically Endosperm forms after double fertilization and stores
denote in flowering plants? nutrients, primarily starch and proteins, which sustain
(A) Fusion of two sperm nuclei with one egg cell embryonic growth. This energy reserve ensures
(B) Fertilization involving two distinct ovules in the successful seed germination and early seedling
same ovary development before the young plant can perform
(C) Fusion of one male gamete with the egg and another photosynthesis and acquire nutrients independently
with the polar nuclei from its surroundings.
(D) Fusion of two polar nuclei in separate embryo sacs
4. Arrange the following events in the correct sequence


Ans during seed formation:
(C) Fusion of one male gamete with the egg and another 1. Fertilization
with the polar nuclei 2. Embryo development
Double fertilization refers to one male gamete fusing 3. Endosperm formation
with the egg cell to form the zygote, and the other male 4. Seed coat hardening
gamete fusing with two polar nuclei to form the triploid (A) 1 → 3 → 2 → 4
endosperm. This unique feature in angiosperms ensures (B) 2 → 1 → 3 → 4
simultaneous embryo and endosperm development (C) 1 → 2 → 3 → 4
for seed nourishment, reflecting a highly efficient (D) 1 → 3 → 4 → 2
reproductive strategy.

Ans
2. Which structure in a mature pollen grain gives rise to (A) 1 → 3 → 2 → 4
the pollen tube during germination? After fertilization (1), the endosperm forms (3). The
(A) Exine embryo then develops (2) within the nutritive tissue.
(B) Intine Finally, the seed coat hardens (4), providing protection
(C) Generative cell and allowing the seed to remain viable until germination
(D) Tube cell conditions are favorable, completing the entire process


Ans of seed development.

(D) Tube cell 5. Which term describes the process of formation of

In flowering plants, the pollen grain typically has two spermatozoa from spermatogonia?
cells: the generative cell and the tube cell. During (A) Oogenesis
germination, the tube cell elongates into the pollen tube (B) Gametogenesis
that delivers male gametes to the ovule. The intine is the (C) Spermatogenesis
inner wall, while the exine is the tough outer wall for (D) Blastulation
protection.

Ans
3. Which of the following is the primary function of (C) Spermatogenesis
endosperm in a developing seed? Spermatogenesis is the process in which diploid
(A) Enhancing cross-pollination mechanisms spermatogonia undergo mitosis and meiosis to produce
(B) Storing and providing nutrients for the embryo haploid spermatozoa. It begins at puberty and continues
(C) Facilitating pollen tube entry throughout life in human males, occurring within the
(D) Protecting the seed coat from damage seminiferous tubules of the testes under hormonal


Ans regulation (FSH, LH, and testosterone).

(B) Storing and providing nutrients for the embryo

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 PRACTICE PAPER 15

6. Identify the correct statements about the menstrual abnormalities or genetic conditions. This procedure
cycle. must be done carefully and ethically, ensuring minimal
1. Progesterone levels rise sharply after ovulation risk to the mother and developing fetus.
2. LH surge triggers ovulation
9. Assertion (A) : Medical termination of pregnancy
3. The follicular phase is dominated by high
progesterone (MTP) can be a lifesaving procedure.
4. Shedding of the endometrium occurs if fertilization Reason (R) : Unsupervised MTP may lead to severe
fails complications and is legally restricted in many regions.
(A) 1, 2, and 3 only (A) Both A and R are true, and R is the correct
(B) 1, 2, and 4 only explanation of A
(C) 2, 3, and 4 only (B) Both A and R are true, but R is not the correct
(D) 1, 3, and 4 only explanation of A
(C) A is true, but R is false


Ans (D) A is false, but R is true
(B) 1, 2, and 4 only

Ans
After ovulation, progesterone increases significantly (1).
The LH surge causes the release of the secondary oocyte (A) Both A and R are true, and R is the correct
(2). If fertilization does not occur, the uterine lining is explanation of A
shed (4). The follicular phase is primarily dominated MTP, when performed under proper medical guidance,
by estrogen rather than progesterone, so statement 3 is can save a mother’s life in certain high-risk pregnancies.
incorrect. However, unsupervised termination can endanger
the mother’s health, which is why it is regulated. The
7. Which of the following does NOT occur during restriction seeks to prevent unsafe practices and protect
oogenesis in humans? maternal well-being.
(A) Meiotic divisions within the ovary
10. Why are Assisted Reproductive Technologies (ART)
(B) Initiation of meiosis during embryonic
development such as IVF vital for certain couples?
(C) Continuous production of ova throughout life (A) They exclusively enhance male fertility
(D) Formation of one functional ovum from each (B) They solely address STDs in females
primary oocyte (C) They help couples with infertility issues to conceive
(D) They eliminate any need for gametes


Ans


Ans
(C) Continuous production of ova throughout life
Unlike sperm formation, ova are not produced (C) They help couples with infertility issues to conceive
continuously throughout life. All primary oocytes in Assisted Reproductive Technologies like In Vitro
humans are formed before birth. Each meiotic event Fertilization (IVF) enable fertilization outside the
typically yields only one functional ovum and three human body. They provide a medical solution for couples
polar bodies, ensuring maximum cytoplasmic reserves with specific infertility challenges, including blocked
in the single viable egg. fallopian tubes or low sperm count, thereby increasing
the chances of achieving a successful pregnancy and
8. Which of the following is primarily used for the childbirth.
detection of certain genetic disorders in a fetus?
11. Match the genetic terms in Column I with their
(A) Amniocentesis
(B) Intrauterine Device (IUD) descriptions in Column II:
(C) Laparoscopy Column I Column II
(D) Follicle Stimulating Hormone (FSH) test 1. Incomplete a. Single gene influencing


Ans dominance multiple traits
(A) Amniocentesis 2. Co-dominance b. Both alleles expressed
Amniocentesis is a prenatal diagnostic technique fully
where amniotic fluid is extracted and analyzed. Fetal 3. Pleiotropy c. More than two allelic
cells in the fluid can be examined for chromosomal forms for a single trait

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14. Why are males more frequently affected by X-linked

4. Multiple alleles d. Intermediate phenotype
in heterozygotes disorders, such as colour blindness?
(A) Males have two X chromosomes
Options:
(B) Males have redundant Y-linked genes
(A) 1-a, 2-d, 3-c, 4-b
(C) Having a single X chromosome increases expression
(B) 1-d, 2-b, 3-a, 4-c
of recessive traits
(C) 1-b, 2-d, 3-c, 4-a
(D) Females have no X chromosomes
(D) 1-d, 2-a, 3-b, 4-c


Ans


Ans
(C) Having a single X chromosome increases expression
(B) 1-d, 2-b, 3-a, 4-c
of recessive traits
In incomplete dominance (1-d), heterozygotes display
X-linked recessive disorders manifest more commonly
an intermediate phenotype. In co-dominance (2-b),
in males because they possess only one X chromosome.
both alleles express equally. Pleiotropy (3-a) occurs
If that X carries a deleterious recessive allele, there is no
when a single gene influences multiple distinct traits.
second X to mask it. Females typically need two copies
Multiple alleles (4-c) imply more than two alternative
of the mutant allele for the same condition to become
forms exist at a particular gene locus.
apparent.
12. Which best describes the genetic inheritance of blood
15. Who famously demonstrated that DNA was the
groups in humans?
transforming principle using heat-killed bacteria?
(A) Simple dominant-recessive pattern with two alleles
(A) Hershey and Chase
(B) Co-dominance involving multiple alleles
(B) Avery, MacLeod, and McCarty
(C) X-linked inheritance restricted to males
(C) Watson and Crick
(D) Example of pleiotropy with incomplete dominance
(D) Meselson and Stahl


Ans


Ans
(B) Co-dominance involving multiple alleles
(B) Avery, MacLeod, and McCarty
Human ABO blood groups are determined by multiple
Avery, MacLeod, and McCarty showed that DNA
alleles (IA, IB, i). Alleles IA and IB can co-express in
extracted from heat-killed virulent bacteria could
heterozygotes (AB blood group). This is a classic case
genetically transform non-virulent bacteria. Their
of co-dominance and multiple allelism, enabling the
experiments provided conclusive evidence that DNA
expression of both A and B antigens on red blood cells
was the hereditary material, building upon Griffith’s
simultaneously.
earlier transformation experiments.
13. How does sex determination differ between humans
16. Match the following molecular processes with the
and birds?
correct enzymes/proteins:
(A) Both species use XX-XY systems
(B) Humans have XX-XY, while birds have ZW-ZZ Column I Column II
systems 1. DNA Replication a. RNA polymerase
(C) Birds have environmental sex determination, while 2. Transcription b. DNA polymerase
humans do not
3. Translation c. Ribosome
(D) Humans have haplo-diploid sex determination,
while birds do not 4. Splicing d. Spliceosome
Options:


Ans
(A) 1-d, 2-a, 3-b, 4-c
(B) Humans have XX-XY, while birds have ZW-ZZ (B) 1-b, 2-a, 3-c, 4-d
systems (C) 1-a, 2-b, 3-d, 4-c
In humans, females are XX and males are XY. In birds, (D) 1-c, 2-d, 3-a, 4-b
females are ZW and males are ZZ. This fundamental


Ans
genetic distinction leads to different patterns of
inheritance, with the mother in birds determining the (B) 1-b, 2-a, 3-c, 4-d
sex of the offspring. DNA polymerase (b) performs replication (1). RNA
polymerase (a) synthesizes RNA during transcription

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 PRACTICE PAPER 15

(2). Ribosomes (c) carry out polypeptide synthesis Natural selection actively favors traits that enhance
in translation (3). Spliceosomes (d) remove introns survival and reproduction, making it a non-random
and join exons during mRNA splicing (4), completing process. Genetic drift is chance fluctuation in allele
essential steps in gene expression. frequencies, especially in small populations, and it
occurs without regard to an individual’s adaptive
17. Which set of statements about the genetic code is advantage or disadvantage.
correct?
1. It is non-overlapping 20. Which is NOT a piece of evidence supporting organic
2. It is universal with rare exceptions evolution?
3. It is ambiguous for certain codons (A) Fossil record showing transitional forms
4. It is degenerate (B) Common genetic code across species
(A) 1, 2, and 4 only (C) Analogous structures arising from convergent
(B) 1, 2, and 3 only evolution
(C) 2, 3, and 4 only (D) Complete absence of homologous structures in
(D) 1, 3, and 4 only vertebrates


Ans

Ans
(A) 1, 2, and 4 only (D) Complete absence of homologous structures in
The genetic code is non-overlapping (1), largely vertebrates
universal (2), and degenerate (4) because multiple Homologous structures are present widely among
codons can code for the same amino acid. However, it vertebrates and indicate common ancestry (e.g., similar
is not ambiguous: each codon specifies only one amino limb bones in various mammals). Fossil records, the
acid. Therefore, statement 3 is incorrect since codons do universal genetic code, and analogous structures also
not code for multiple amino acids. provide evolutionary insights. Thus, stating a complete
absence of homologous structures is false and not
18. The process in which an mRNA strand directs the evidence against evolution.
assembly of a polypeptide is called:
(A) Transcription 21. Arrange the following evolutionary events in the correct
(B) Translation sequence:
(C) Replication 1. Formation of simple organic molecules
(D) Transformation 2. Origin of self-replicating RNA


Ans 3. Appearance of anaerobic prokaryotes
4. Evolution of photosynthetic organisms
(B) Translation (A) 1 → 2 → 3 → 4
Translation is the process by which the ribosome reads (B) 2 → 1 → 4 → 3
the sequence of bases in mRNA to assemble amino acids (C) 1 → 3 → 2 → 4
into a polypeptide chain. The sequence of codons in (D) 2 → 3 → 1 → 4
mRNA determines the specific sequence of amino acids,
reflecting the information originally encoded in DNA.

Ans
(A) 1 → 2 → 3 → 4
19. Which key distinction separates natural selection from Simple organic molecules formed first (1), followed by
genetic drift? the emergence of self-replicating RNA (2). Anaerobic
(A) Genetic drift selects based on fitness prokaryotes then appeared (3) before some developed
(B) Natural selection is random; genetic drift is based photosynthetic capabilities (4). This sequence outlines
on fitness key transitional stages in the origin and development of
(C) Natural selection is non-random; genetic drift is life on Earth.
random
(D) Both are equally controlled by environmental 22. Assertion (A) : Vaccinations stimulate the body to
factors produce antibodies against specific pathogens.


Ans Reason (R) : Vaccines typically contain fully active
forms of dangerous pathogens.
(C) Natural selection is non-random; genetic drift is (A) Both A and R are true, and R is the correct
random

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page 150 CUET UG Biology

explanation of A (B) They synthesize gluten

(B) Both A and R are true, but R is not the correct (C) They release carbon dioxide causing dough to rise
explanation of A (D) They remove all carbohydrates from flour
(C) A is true, but R is false

Ans
(D) A is false, but R is true
(C) They release carbon dioxide causing dough to rise


Ans Yeast ferments sugars in the dough, producing carbon
(C) A is true, but R is false dioxide that forms air pockets, resulting in a soft and
Vaccines trigger the immune system to produce porous texture. This biological process also develops
antibodies, conferring immunity. However, they usually characteristic flavors, demonstrating the industrial
consist of killed or weakened forms of the pathogen, not and culinary value of microbial fermentation in food
fully active dangerous forms. This ensures the body can processing.
mount an immune response safely, minimizing the risk
26. Which combination of statements regarding sewage
of full-blown infection.
treatment is correct?
23. How do infectious diseases like malaria differ from non- 1. Primary treatment physically removes large
communicable diseases such as cancer? particles
(A) Infectious diseases arise spontaneously, cancer is 2. Secondary treatment uses microbial action
always inherited 3. Tertiary treatment is always omitted
(B) Cancer spreads among individuals via vectors 4. Sludge can be used as biogas feedstock
(C) Infectious diseases can transmit from person to (A) 1, 2, and 3 only
person or via vectors, cancer does not (B) 1, 2, and 4 only
(D) Both are controlled only by antibiotics (C) 2, 3, and 4 only


Ans (D) 1, 3, and 4 only

(C) Infectious diseases can transmit from person to

Ans

person or via vectors, cancer does not (B) 1, 2, and 4 only
Infectious diseases, caused by pathogens, can spread Municipal wastewater usually undergoes primary
from one host to another via direct contact or vectors. treatment (physical screening) and secondary treatment
Cancer generally involves uncontrolled cell division (biological), and sometimes advanced or tertiary
within an individual and is not transmitted between treatment if needed. Sludge from primary sedimentation
people. Treatments and preventive strategies also differ or secondary clarifiers can be digested to produce biogas.
significantly. Statement 3 is incorrect because tertiary treatment can
be included when required.
24. What is the primary causative organism of filariasis in
humans? 27. Which statement about antibiotics is FALSE?
(A) Plasmodium vivax (A) They are used to treat bacterial infections
(B) Wuchereria bancrofti (B) They can become less effective due to resistance
(C) Entamoeba histolytica (C) They target viral replication specifically
(D) Mycobacterium tuberculosis (D) Overuse can harm beneficial microbiota


Ans

Ans
(B) Wuchereria bancrofti (C) They target viral replication specifically
Filariasis, commonly presenting with swelling of limbs Antibiotics are aimed at bacterial structures or
(elephantiasis), is caused by the parasitic nematode metabolic pathways, not viral replication. Overuse or
Wuchereria bancrofti. It is transmitted by mosquitoes. misuse can encourage antibiotic-resistant bacteria and
Prolonged infection leads to significant lymphatic disrupt normal flora. Their function does not include
damage and lymphedema, highlighting the importance eliminating viruses, which typically require antiviral
of effective vector control and early diagnosis. drugs or vaccines for control.

25. Why are fermenting microbes like yeast essential in 28. Which microbe is widely used in the production of
bread-making? citric acid industrially?
(A) They form protein networks in dough (A) Aspergillus niger

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 PRACTICE PAPER 15

(B) Penicillium chrysogenum

Ans

(C) Saccharomyces cerevisiae (C) They allow complementary base pairing for efficient
(D) Lactobacillus bulgaricus ligation


Ans Some restriction enzymes produce staggered cuts that
leave overhanging sequences known as “sticky ends.”
(A) Aspergillus niger
These complementary overhangs can hydrogen-bond
Aspergillus niger is a filamentous fungus extensively
with matching sequences on the insert DNA, greatly
employed for large-scale citric acid fermentation. It
improving the efficiency and specificity of ligation
converts sugars in a culture medium to citric acid,
during recombinant DNA technology procedures.
which is then purified for use in food industries,
pharmaceuticals, and other applications. 32. Which is the principal benefit of genetically engineered
Bt crops?
29. Which component is a key molecular “vehicle” used
(A) Enhanced tolerance to viral infections
to carry foreign DNA into host cells during genetic
(B) Increased salt tolerance in aquatic environments
engineering?
(C) Reduction in pest infestation and decreased
(A) Restriction enzyme
insecticide use
(B) Ligase
(D) Accelerated rate of photosynthesis
(C) Vector
(D) Host cell wall

Ans

Ans (C) Reduction in pest infestation and decreased

insecticide use
(C) Vector
Bt crops, engineered to produce Bacillus thuringiensis
A vector, typically a plasmid or a bacteriophage,
toxin, target specific insect pests. This can significantly
facilitates the transfer and replication of foreign DNA
reduce crop damage and minimize reliance on chemical
inside a host organism. Restriction enzymes cut DNA,
insecticides. As a result, farmers benefit from better
ligases join DNA fragments, while the cell wall is simply
yields and reduced environmental impact compared to
a structural barrier and not a vehicle for gene transfer.
traditional insecticide-based control strategies.
30. Which enzyme is responsible for sealing nicks in the
33. Which technology involves replacing a defective gene
sugar-phosphate backbone during recombinant DNA
with a functional gene to treat genetic disorders?
construction?
(A) Gene therapy
(A) DNA polymerase
(B) Polymerase Chain Reaction (PCR)
(B) Restriction endonuclease
(C) ZIFT
(C) DNA ligase
(D) Organ donation
(D) RNA polymerase


Ans


Ans
(A) Gene therapy
(C) DNA ligase
Gene therapy is the technique wherein a normal,
DNA ligase covalently joins the sugar-phosphate
functional gene is inserted into a patient’s cells to
backbones, closing nicks that remain after restriction
compensate for a defective or missing gene. Though
enzymes cut and complementary bases anneal. This
still experimental in many cases, it holds promise for
forms a stable recombinant DNA molecule, which can
treating various inherited diseases and some acquired
be introduced into a suitable host for replication and
conditions.
expression of the desired gene.
34. How do transgenic animals differ from naturally bred
31. Why are “sticky ends” formed by restriction enzymes
variants?
advantageous in cloning?
(A) Transgenic animals are always sterile
(A) They degrade the inserted gene quickly
(B) Transgenic animals have artificially introduced
(B) They prevent the plasmid from forming
genes
(C) They allow complementary base pairing for efficient
(C) Naturally bred variants have no genetic alterations
ligation
(D) Both have identical genomes
(D) They keep DNA single-stranded permanently


Ans

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(B) Transgenic animals have artificially introduced (A) The range of habitats occupied
genes (B) The total biomass
Transgenic animals carry foreign DNA inserted (C) The proportion of individuals of different ages
deliberately into their genome, whereas naturally bred (D) The difference in birth and death rates only
variants acquire genetic diversity through conventional

Ans
reproduction or random mutations. This controlled
genetic modification in transgenic lines can result in (C) The proportion of individuals of different ages
novel traits for research, pharmaceutical production, or Age distribution refers to how the population is divided
agricultural improvements. among various age groups (e.g., juvenile, reproductive,
post-reproductive). This influences population growth
35. Match the following population interactions with their trends and stability, as younger or reproductive segments
correct descriptions: can significantly affect future population dynamics.
Column I Column II 38. Identify the correct statements about energy flow in an
1. Mutualism a. One organism benefits, the ecosystem:
other is harmed 1. Energy flow is unidirectional
2. Competition b. Both organisms benefit 2. Energy is recycled at each trophic level
3. Predation c. Both suffer due to limited 3. Producers capture solar energy
resources 4. Apex predators receive the greatest energy
(A) 1, 2, and 4 only
4. Parasitism d. One benefits at the expense
(B) 1, 3, and 4 only
of prey
(C) 1, 2, and 3 only
Options: (D) 1 and 3 only
(A) 1-b, 2-a, 3-d, 4-c


Ans
(B) 1-b, 2-c, 3-d, 4-a
(C) 1-a, 2-c, 3-b, 4-d (D) 1 and 3 only
(D) 1-c, 2-d, 3-a, 4-b Energy flow in an ecosystem is unidirectional (1).
Producers fix solar energy (3). Energy is not recycled


Ans
but is lost as heat at each trophic level, so statement 2 is
(B) 1-b, 2-c, 3-d, 4-a incorrect. Apex predators, being at the top, receive the
Mutualism benefits both (1-b), competition hinders least energy due to cumulative losses.
both (2-c), predation benefits one at the expense of the
prey (3-d), and parasitism also benefits one organism 39. Match the following terms with their description:
while harming the host (4-a). These interactions shape Column I Column II
population dynamics in ecosystems.
1. Productivity a. Sequence of who eats
36. Why do parasites typically not kill their hosts quickly? whom
(A) They lack any genetic material 2. Decomposition b. Total organic matter
(B) They need the host alive to ensure a continuous produced
supply of nutrients 3. Pyramid of c. Weight of living organisms
(C) They cannot reproduce in living cells biomass at each trophic level
(D) They only rely on external vectors for survival
4. Food chain d. Breakdown of organic


Ans matter by microbes
(B) They need the host alive to ensure a continuous Options:
supply of nutrients (A) 1-d, 2-b, 3-a, 4-c
Parasites often evolve strategies to keep their hosts (B) 1-b, 2-d, 3-c, 4-a
alive and functioning since their survival, growth, and (C) 1-a, 2-c, 3-d, 4-b
reproduction depend on extracting resources from (D) 1-c, 2-a, 3-b, 4-d
the host. Rapid killing would limit the parasite’s own

Ans
propagation, so a delicate balance typically evolves.
(B) 1-b, 2-d, 3-c, 4-a
37. What does “age distribution” in a population describe?

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 PRACTICE PAPER 15

Productivity (1-b) is the total organic matter formed importance of masks and hygiene measures to limit
by producers. Decomposition (2-d) involves microbial disease transmission.
breakdown of dead organic matter. A pyramid of
42. Which protective measure is emphasized to prevent the
biomass (3-c) represents the weight of organisms at
each trophic level. A food chain (4-a) shows the feeding spread of this virus?
sequence. (A) Avoiding vegetables
(B) Maintaining good hygiene
40. Which best explains why energy pyramids typically (C) Increasing sugar intake
narrow at the top? (D) Obtaining genetic counseling
(A) There is a sudden increase in predator populations

Ans
(B) Energy is stored equally in each level
(C) Significant energy is lost as heat in metabolic (B) Maintaining good hygiene
processes Medical professionals highlight the significance of
(D) Primary consumers assimilate all producer energy hygiene practices (like handwashing and sanitizing)
to reduce viral spread. Such preventive measures are


Ans especially important when facing droplet-transmitted
(C) Significant energy is lost as heat in metabolic illnesses, as they lower the likelihood of contact with
processes infected respiratory secretions.
At each trophic level, organisms use a portion of the
43. Why did researchers use inactivated viral particles in
energy for metabolic activities, releasing heat and
reducing the energy available to higher levels. This vaccine trials?
progressive loss of usable energy results in pyramids (A) To enhance virus replication
that are broad at the base (producers) and narrow (B) To ensure a safer immune response without causing
toward apex consumers. the actual disease
(C) To maximize the virus’s ability to mutate


Direction :Carefully read the case study provided and then (D) To eliminate any immune response in recipients
thoroughly answer the subsequent five questions.

Ans
A research team investigated a new viral disease affecting
the human respiratory system. They observed that the (B) To ensure a safer immune response without causing
virus spreads through droplets and attacks the lung tissue, the actual disease
leading to inflammation and reduced oxygen exchange. Inactivated viral vaccines contain viruses that have
Vaccination trials used inactivated viral particles to been killed or rendered non-infectious while retaining
stimulate immune response. Patients receiving the vaccine antigenic properties. This approach helps the immune
showed fewer symptoms and faster recovery. However, system recognize key viral proteins and develop
some participants displayed mild side effects, prompting protective antibodies, reducing the risk of inducing the
further safety evaluations. Medical professionals stress actual disease in vaccine recipients.
that vigilance and proper hygiene are vital to contain 44. What is the primary clinical benefit observed in
viral outbreaks and protect vulnerable populations. vaccinated individuals?
41. What is the main mode of transmission of this viral (A) Complete eradication of all viral strains
disease? (B) Zero risk of any infection
(A) Contaminated food (C) Fewer symptoms and faster recovery
(B) Insect vectors (D) Inability to transmit the virus to others
(C) Droplet spread

Ans
(D) Sexual contact (C) Fewer symptoms and faster recovery


Ans Vaccinated participants in the trials exhibited milder
(C) Droplet spread illness and recovered more swiftly. Vaccines generally
Based on the case study, the virus primarily transmits reduce disease severity and hospitalization rates,
through respiratory droplets. When infected individuals although they may not always prevent infections
cough or sneeze, these droplets can carry viral particles entirely. They also curtail transmission and safeguard
to others. This method of spread underscores the at-risk populations by promoting community-level
immunity.

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45. Why did some participants experience mild side effects nearby crops
after vaccination? (D) Inability to control weed growth
(A) Because the vaccine caused a severe active infection

Ans
(B) Due to general immune responses to introduced
antigens (C) Potential adverse effects on soil microbes and
(C) Because the virus was incompletely inactivated nearby crops
(D) Due to absolute lack of any immune mechanism Critics worry that introducing GM crops could
disrupt soil microbial communities and potentially


Ans cross-pollinate with non-GM varieties. Such concerns
(B) Due to general immune responses to introduced underscore the need for comprehensive environmental
antigens risk assessments and management strategies to
Vaccination often triggers temporary side effects (e.g., safeguard ecological balance.
fever, soreness) as the immune system recognizes and
48. Why did scientists recommend buffer zones around GM
responds to antigens. These mild symptoms indicate a
protective immunological process. They are typically cotton fields?
short-lived and far less dangerous than the actual (A) To increase the cost of seeds
disease. (B) To promote insect pollination in all fields
(C) To isolate GM plants from neighboring crops and


Direction :Carefully read the case study provided and then reduce unintended spread
thoroughly answer the subsequent five questions. (D) To reduce legal restrictions on farmers
A local agricultural extension program introduced

Ans
genetically modified (GM) cotton seeds resistant to a
common fungal pathogen. Over one season, farmers (C) To isolate GM plants from neighboring crops and
observed higher yields and less fungal damage. However, reduce unintended spread
environmental groups raised concerns about potential Buffer zones physically separate GM fields from non-
effects on beneficial soil microbes and neighboring non- GM fields, minimizing cross-pollination and seed
GM crops. Scientists recommended monitoring soil health dispersal. This measure also helps protect organic and
indicators and implementing buffer zones. Farmers conventional farming interests while maintaining
welcomed the enhanced protection, yet remained cautious biodiversity and addressing concerns about genetic
about the long-term ecological impact of GM technology. contamination of surrounding areas.

49. In what way did farmers respond to the new GM seeds?

46. What was the primary benefit observed by farmers
growing the new GM cotton? (A) They completely refused to try them
(A) Increase in predator insect populations (B) They embraced them for higher protection but
(B) Enhanced fungal resistance leading to higher yields stayed aware of ecological risks
(C) Elimination of all ecological concerns (C) They replaced the seeds with non-GM varieties
(D) Shift from cotton to other cash crops (D) They requested government bans on GM crops

Ans

Ans

(B) Enhanced fungal resistance leading to higher yields (B) They embraced them for higher protection but
The GM cotton seeds are designed to resist a damaging stayed aware of ecological risks
fungal pathogen, which reduces crop losses. Farmers Farmers appreciated the enhanced disease resistance
reported improved yields, indicating that the genetic and resulting yield gains, but they also recognized
modification successfully mitigated the fungal potential environmental implications. Their measured
disease impact, thereby enhancing overall production acceptance underscores how economic benefits must be
performance. balanced with prudent environmental stewardship and
regulatory compliance to ensure sustainable farming
47. Which major concern did environmental groups practices.
express?
50. Why is continuous monitoring of soil health indicators
(A) Rapid human population growth
(B) Sudden decline in cotton market prices important in GM crop fields?
(C) Potential adverse effects on soil microbes and (A) To ensure mandatory doubling of fertilizer inputs
(B) To guarantee no legal compliance is ever required

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 PRACTICE PAPER 15

(C) To detect any negative changes in microbial

populations or nutrient cycles
(D) To prohibit all future GMO trials


Ans
(C) To detect any negative changes in microbial
populations or nutrient cycles
Ongoing assessment of soil composition, microbial
diversity, and nutrient cycles is critical to identify any
unintended consequences of GM crop cultivation. Early
detection of ecological disruptions allows for timely
mitigation measures, ensuring the sustainability of both
GM and non-GM agricultural systems.

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PRACTICE PAPER 16

1. Which one of the following is a pollination adaptation in pollination unless other mechanisms exist, making this
wind-pollinated flowers? the exception in preventing it.
(A) Bright petals to attract insects
4. Select the correct set of statements regarding
(B) Sticky pollen grains
(C) Production of large quantities of light pollen spermatogenesis:
(D) Nectar production for bats 1. It begins at birth in males
2. It occurs in the seminiferous tubules of the testes


Ans 3. FSH and testosterone are important hormones
(C) Production of large quantities of light pollen 4. Four functional sperm cells result from one primary
Wind-pollinated flowers typically release abundant spermatocyte
lightweight pollen grains. This characteristic helps pollen (A) 2, 3, and 4 only
travel long distances by air currents to ensure successful (B) 1, 2, and 4 only
fertilization, compensating for the randomness of wind (C) 1, 3, and 4 only
dispersal. (D) 1, 2, and 3 only

2. Why is polyembryony advantageous in some plant

Ans

species? (A) 2, 3, and 4 only
(A) It reduces genetic variability Spermatogenesis starts at puberty (not birth), occurs
(B) It ensures multiple embryos from a single seed in the seminiferous tubules (2), and depends heavily
(C) It always produces non-viable offspring on FSH and testosterone (3). Meiosis of one primary
(D) It impedes embryo formation entirely spermatocyte yields four functional sperm cells (4).


Ans Therefore, statement 1 is incorrect.

(B) It ensures multiple embryos from a single seed 5. Which best explains why the testes are located in the
Polyembryony is the formation of more than one embryo scrotum rather than inside the abdomen?
within the same seed. This can enhance the chances of (A) To decrease blood supply
survival by producing multiple seedlings, especially (B) To maintain an optimal temperature for
under uncertain environmental conditions, offering a spermatogenesis
built-in redundancy for the plant’s reproductive success. (C) To protect them from minor injuries
(D) To allow them to develop after birth
3. Which of the following does NOT help prevent self-
pollination in flowering plants?

Ans
(A) Anther and stigma maturing at different times (B) To maintain an optimal temperature for
(B) Presence of self-incompatibility genes spermatogenesis
(C) Monoecious arrangement with closely located The scrotal sac holds the testes at a slightly lower
anther and stigma temperature than the body’s core. This cooler
(D) Structural barriers like herkogamy environment is crucial for efficient sperm production.


Ans Higher internal body temperatures can impair
spermatogenesis and reduce fertility.
(C) Monoecious arrangement with closely located
anther and stigma 6. What does “implantation” refer to in human
Spatial or temporal separation (e.g., herkogamy reproduction?
or differing maturation times) and genetic self- (A) Fusion of sperm with ovum in the fallopian tube
incompatibility prevent self-pollination. A monoecious (B) Release of the secondary oocyte from the ovary
plant with anther and stigma nearby may promote self- (C) Attachment of the blastocyst to the uterine wall

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(D) Rupture of the mature follicle

Ans

Ans (B) Both A and R are true, but R is not the correct
explanation of A
(C) Attachment of the blastocyst to the uterine wall
Protected sex via condoms significantly lowers STD
Implantation occurs when the blastocyst, formed
transmission rates, so raising awareness helps. Complete
after fertilization and early cell divisions, attaches and
abstinence indeed ensures no pregnancy occurs, but it
embeds into the endometrial lining. This event is critical
is not the explanation behind reduced STD prevalence.
for establishing the nutrient supply from the maternal
Safer-sex practices directly reduce infection risks.
blood, enabling the embryo to develop successfully.
10. Which is NOT typically a feature of Mendelian
7. How do intrauterine devices (IUDs) differ from oral
inheritance?
contraceptive pills?
(A) Segregation of alleles during gamete formation
(A) IUDs prevent ovulation, while pills block
(B) Independent assortment in dihybrid crosses
implantation
(C) Equal expression of both alleles in the heterozygote
(B) IUDs are inserted in the uterus, while pills are taken
(D) Dominant allele masking the recessive allele in
orally
heterozygotes
(C) Both rely on daily dosage routines
(D) Pills reduce the risk of STDs, whereas IUDs do not

Ans

Ans (C) Equal expression of both alleles in the heterozygote

In classic Mendelian inheritance, the dominant allele
(B) IUDs are inserted in the uterus, while pills are taken
masks the recessive one in heterozygotes. Equal
orally
expression of both alleles refers to co-dominance,
IUDs are physical or hormonal devices placed inside
which is a deviation from strict Mendelian dominance-
the uterus, often providing long-term contraception.
recessive patterns.
Oral contraceptive pills are ingested daily to regulate
hormones and prevent ovulation. Hence, their route of 11. What does the term “linkage” refer to in genetics?
administration and mechanism vary substantially. (A) Unrelated genes randomly assorting
(B) Genes located on different chromosomes
8. Which of the following is a common sexually transmitted
(C) Tendency of genes on the same chromosome to be
disease caused by a bacterium?
inherited together
(A) Genital warts
(D) Complete dominance of one gene over another
(B) Gonorrhea
(C) HIV/AIDS

Ans
(D) Hepatitis B (C) Tendency of genes on the same chromosome to be


Ans inherited together
Linkage occurs because genes present on the same
(B) Gonorrhea
chromosome do not assort independently if they are
Gonorrhea is an STD caused by the bacterium Neisseria
close together, reducing recombination frequency. The
gonorrhoeae. Other STDs mentioned are caused by
phenomenon helps explain exceptions to Mendel’s law
viruses. Early detection and antibiotic treatment are
of independent assortment in dihybrid or multihybrid
critical for preventing complications such as pelvic
crosses.
inflammatory disease or infertility.
12. Match the genetic disorders in Column I with the type
9. Assertion (A) : Awareness programs promoting
of inheritance in Column II:
protected sex can reduce the prevalence of STDs.
Reason (R) : Complete abstinence is the only guaranteed Column I Column II
method to prevent pregnancy. 1. Haemophilia a. Autosomal recessive
(A) Both A and R are true, and R is the correct 2. Thalassemia b. X-linked recessive
explanation of A
3. Down’s syndrome c. Trisomy 21
(B) Both A and R are true, but R is not the correct
explanation of A 4. Klinefelter’s d. XXY condition
(C) A is true, but R is false syndrome
(D) A is false, but R is true Options:

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(A) 1-a, 2-b, 3-d, 4-c (C) Deoxyribose and phosphate

(B) 1-b, 2-c, 3-a, 4-d (D) Deoxyribose and uracil
(C) 1-b, 2-a, 3-c, 4-d

Ans
(D) 1-d, 2-a, 3-b, 4-c
(C) Deoxyribose and phosphate


Ans The sugar-phosphate backbone of DNA is composed
(C) 1-b, 2-a, 3-c, 4-d of deoxyribose sugars linked via phosphate groups.
Haemophilia (1-b) is commonly X-linked recessive. Nitrogenous bases (A, T, G, C) extend from this backbone,
Thalassemia (2-a) is frequently autosomal recessive. forming hydrogen bonds with complementary bases on
Down’s syndrome (3-c) involves trisomy of chromosome the opposite strand.
21. Klinefelter’s syndrome (4-d) arises from the XXY
16. What is “genetic drift”?
chromosomal pattern.
(A) Selection favoring the most adapted phenotypes
13. How does DNA differ from RNA in most organisms? (B) Random changes in allele frequencies in small
(A) DNA contains uracil, while RNA contains thymine populations
(B) DNA typically remains single-stranded, while RNA (C) Directional change in a trait due to environmental
is double-stranded pressure
(C) DNA contains deoxyribose sugar, while RNA (D) Transfer of alleles between populations
contains ribose

Ans
(D) Both are identical except for length
(B) Random changes in allele frequencies in small


Ans populations
(C) DNA contains deoxyribose sugar, while RNA Genetic drift is a stochastic process whereby chance
contains ribose events can significantly alter allele frequencies,
DNA has deoxyribose sugar and thymine, whereas particularly in small populations. It is not driven by
RNA contains ribose sugar and uracil. These structural natural selection but by random sampling of alleles from
differences account for their distinct roles in genetic one generation to the next.
storage (DNA) versus protein synthesis and regulation
17. Why did Darwin’s finches provide strong evidence for
(RNA).
natural selection?
14. Which best describes the outcome of the Meselson and (A) They displayed no variation in beak shapes
Stahl experiment? (B) They were found in identical habitats around the
(A) They disproved DNA replication world
(B) They established conservative replication in (C) Their beak variations were closely related to their
bacteria diets
(C) They provided evidence for semi-conservative (D) They did not reproduce in the wild
replication of DNA

Ans
(D) They confirmed a universal code for all proteins
(C) Their beak variations were closely related to their


Ans diets
(C) They provided evidence for semi-conservative Darwin observed that finches on different Galápagos
replication of DNA Islands had beaks adapted to specific food sources.
Meselson and Stahl labeled bacterial DNA with heavy This correlation between beak form and feeding habits
nitrogen, demonstrating that each new DNA double exemplified how environmental pressures could shape
helix contains one old strand and one newly synthesized physical traits, supporting his theory of natural selection.
strand. This provided strong experimental proof for
18. Choose the correct combination of statements about the
semi-conservative replication in prokaryotes, a model
later confirmed in eukaryotes. Hardy-Weinberg principle:
1. It describes genetic equilibrium in a large
15. Which component forms the “backbone” of a DNA population with random mating
strand? 2. Mutation and gene flow must be absent for
(A) Ribose and phosphate equilibrium
(B) Adenine and thymine bases 3. Frequency of recessive allele is always constant,

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 PRACTICE PAPER 16

even if selection occurs (D) Primary sludge is formed during aeration, while
4. No natural selection is assumed activated sludge settles in clarifiers
5. Genetic drift has no impact on large populations

Ans
(A) 1, 2, 4, and 5 only
(B) 1, 2, 3, and 5 only (B) Activated sludge is rich in microbes, while primary
(C) 2, 3, 4, and 5 only sludge is mostly settled solids
(D) 1, 3, 4, and 5 only Primary sludge forms during primary sedimentation,
containing large solid particles. Activated sludge is


Ans produced after aeration, where microbial populations
(A) 1, 2, 4, and 5 only aggregate to form flocs. These flocs break down organic
The Hardy-Weinberg principle states that in a large, matter more effectively, reducing pollution load in
randomly mating population with no mutation, no sewage treatment.
migration, and no natural selection, allele frequencies
22. Which best describes why Lactobacillus species are used
remain constant (1, 2, 4). Genetic drift is negligible in
very large populations (5). If selection occurs, allele in curd production?
frequencies can change, so statement 3 is incorrect. (A) They require intense light to ferment lactose
(B) They are parasites that feed on milk proteins
19. Which pathogen is primarily responsible for causing (C) They convert lactose into lactic acid, coagulating
typhoid fever? milk proteins
(A) Salmonella typhi (D) They produce strong alcohol from milk sugar
(B) Vibrio cholerae

Ans
(C) Plasmodium falciparum
(D) Trypanosoma gambiense (C) They convert lactose into lactic acid, coagulating
milk proteins


Ans Lactobacillus ferments the lactose in milk, generating
(A) Salmonella typhi lactic acid. The acidic environment coagulates milk
Typhoid fever is caused by the bacterium Salmonella proteins, transforming fluid milk into thicker curd.
typhi, usually transmitted through contaminated food This fermentation imparts the characteristic taste and
or water. Prompt diagnosis and antibiotic treatment are texture that define traditional curd products.
essential to prevent severe systemic complications.
23. Match the microbes in Column I with their applications
20. Which immune cells are primarily responsible for in Column II:
antibody production?
Column I Column II
(A) Macrophages
(B) Neutrophils 1. Penicillium notatum a. Bread and beverage
(C) B-lymphocytes fermentation
(D) Erythrocytes 2. Saccharomyces b. Vinegar production
cerevisiae


Ans
3. Methanobacterium c. Biogas generation
(C) B-lymphocytes
4. Acetobacter aceti d. Antibiotic penicillin
B-lymphocytes differentiate into plasma cells
that synthesize and secrete antibodies. These Options:
immunoglobulins bind specifically to antigens, marking (A) 1-a, 2-d, 3-b, 4-c
pathogens for destruction or neutralizing toxins, (B) 1-d, 2-a, 3-c, 4-b
forming a critical component of humoral immunity. (C) 1-d, 2-b, 3-a, 4-c
(D) 1-c, 2-a, 3-d, 4-b
21. How does primary sludge differ from activated sludge in


Ans
sewage treatment?
(A) Primary sludge is highly biodegradable, while (B) 1-d, 2-a, 3-c, 4-b
activated sludge is not Penicillium notatum (1-d) produces penicillin.
(B) Activated sludge is rich in microbes, while primary Saccharomyces cerevisiae (2-a) is the yeast used in
sludge is mostly settled solids baking and alcohol fermentation. Methanobacterium
(C) Both undergo no further processing (3-c) is involved in biogas (methane) production.

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Acetobacter aceti (4-b) oxidizes ethanol to acetic acid (A) Bacillus thuringiensis
for vinegar. (B) Escherichia coli
(C) Rhizobium leguminosarum
24. Which is the role of restriction endonucleases in genetic (D) Salmonella typhi
engineering?
(A) To amplify DNA segments

Ans
(B) To form phosphodiester bonds (A) Bacillus thuringiensis
(C) To cut DNA at specific recognition sites Bacillus thuringiensis is a soil bacterium that synthesizes
(D) To denature proteins protein crystals toxic to certain insects. This gene, when


Ans transferred to crops (e.g., Bt cotton), provides inherent
pest resistance and reduces the need for chemical
(C) To cut DNA at specific recognition sites insecticides.
Restriction endonucleases, often called “molecular
scissors,” recognize short, specific DNA sequences and 28. Why is gene therapy still largely experimental for human
cleave the sugar-phosphate backbone. This precise disease treatment?
cutting is essential for cloning, allowing insertion of (A) Many diseases are cured exclusively by antibiotics
foreign DNA fragments into vectors for recombinant (B) Ethical and technical challenges, like gene delivery
DNA creation. methods, remain unresolved
(C) Gene therapy is cheaper and more common than
25. Which step is NOT typically part of the Polymerase standard medicine
Chain Reaction (PCR)? (D) It only works in plants, not humans
(A) Denaturation of DNA strands
(B) Annealing of primers

Ans
(C) Extension by Taq DNA polymerase (B) Ethical and technical challenges, like gene delivery
(D) Introduction of rRNA genes to degrade product methods, remain unresolved


Ans Gene therapy faces hurdles in ensuring safe and
efficient delivery of genes into human cells without
(D) Introduction of rRNA genes to degrade product adverse immune reactions or off-target effects. Ethical
PCR involves denaturing the double-stranded DNA, considerations regarding modifying the human genome
annealing primers, and extending the new DNA strands also hinder widespread clinical application.
using Taq polymerase in repeated cycles. There is no
addition of rRNA genes to degrade the product in 29. Why is population density an important ecological
standard PCR protocols. parameter?
(A) It shows the exact genetic makeup of the population
26. What is “biopiracy”? (B) It represents how the species interacts with
(A) The legal patenting of indigenous knowledge resources and competitors
(B) Unauthorized commercial exploitation of biological (C) It solely indicates the number of offspring produced
resources (D) It measures only the predator population size
(C) Government-led conservation of biodiversity
(D) Official licensing of GM crop exports

Ans

Ans (B) It represents how the species interacts with resources

and competitors
(B) Unauthorized commercial exploitation of biological Population density indicates how many individuals
resources occupy a given area or volume. High densities can
Biopiracy is the practice of patenting or using genetic intensify competition for resources or increase disease
resources and traditional knowledge from one region spread, while low densities might hinder mating
without compensating or acknowledging local opportunities. This measure is central to understanding
communities. It often involves multinational companies population ecology.
capitalizing on native plant or microbial properties
without sharing benefits. 30. Assertion (A) : In parasitism, the host is harmed.
Reason (R) : The parasite extracts resources from the
27. Which organism produces the Bt toxin gene used in host, sometimes reducing the host’s fitness.
some genetically modified crops?

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 PRACTICE PAPER 16

(A) Both A and R are true, and R is the correct 33. Match the levels of an energy pyramid in Column I with
explanation of A appropriate examples in Column II:
(B) Both A and R are true, but R is not the correct
Column I Column II
explanation of A
(C) A is true, but R is false 1. Tertiary consumers a. Grass
(D) A is false, but R is true 2. Primary consumers b. Grasshopper


Ans 3. Producers c. Snake
4. Secondary consumers d. Hawk
(A) Both A and R are true, and R is the correct
explanation of A Options:
Parasitism inherently harms the host because the (A) 1-b, 2-a, 3-d, 4-c
parasite draws nutrients or resources. This can weaken (B) 1-c, 2-b, 3-a, 4-d
or reduce host survival and reproductive potential. The (C) 1-d, 2-b, 3-a, 4-c
reason directly clarifies the causal link between the (D) 1-a, 2-d, 3-b, 4-c
parasite’s activity and the harm inflicted.

Ans

31. Which statement describes “productivity” in an (C) 1-d, 2-b, 3-a, 4-c
ecosystem? Producers (3-a) are plants like grass. Primary consumers
(A) Rate of water evaporation by plants (2-b) are herbivores such as grasshoppers. Secondary
(B) Rate of biomass generation per unit area over time consumers (4-c) can be carnivores like snakes, which
(C) Number of predators in the food web feed on primary consumers. Tertiary consumers (1-d),
(D) Amount of seasonal migration in an area such as hawks, may feed on secondary consumers.


Ans 34. Identify the correct combination of statements about
(B) Rate of biomass generation per unit area over time biodiversity conservation:
Ecosystem productivity, expressed as primary 1. Biodiversity hotspots have high endemism
productivity for producers, measures how much organic 2. Sacred groves are culturally protected forest patches
matter is synthesized. It reflects energy fixation from 3. Red Data Book lists extinct species only
sunlight (in photosynthetic ecosystems) into biomass, 4. In situ conservation protects species in their natural
fundamental to supporting higher trophic levels. habitats
5. Ex situ conservation involves creating natural
32. How does primary productivity differ from secondary corridors for wildlife
productivity? (A) 1, 2, and 4 only
(A) Both refer to photosynthetic organisms (B) 1, 3, and 5 only
(B) Primary productivity occurs in consumers, (C) 2, 4, and 5 only
secondary in producers (D) 1, 2, 4, and 5 only
(C) Primary productivity is by autotrophs, secondary


Ans
productivity is by heterotrophs
(D) They are the same process observed at different (A) 1, 2, and 4 only
seasons Biodiversity hotspots have exceptional species richness
and endemism (1). Sacred groves are protected due to


Ans
cultural and religious values (2). In situ conservation
(C) Primary productivity is by autotrophs, secondary maintains organisms in their natural surroundings (4).
productivity is by heterotrophs The Red Data Book also includes endangered species,
Primary productivity is the synthesis of organic not just extinct; corridors are part of in situ strategies,
compounds by producers (autotrophs). Secondary not ex situ.
productivity encompasses the biomass gained by
consumers (heterotrophs) from feeding on primary 35. Which is a primary reason for the loss of biodiversity?
producers or other organisms. These distinct processes (A) Overexploitation and habitat destruction
sustain the flow of energy in ecosystems. (B) Expanded gene banks
(C) Strict wildlife protection laws
(D) Scientific research on micropropagation

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Ans
3. Sacred Groves c. Large protected areas
(A) Overexploitation and habitat destruction maintained primarily for
Human-driven activities like deforestation, pollution, wildlife protection and
overhunting, and unsustainable resource use are ecosystem preservation
major factors depleting species diversity worldwide. In 4. Ramsar Sites d. Protected areas where
contrast, protective legislation and research can enhance some regulated human
conservation efforts. activity is permitted
36. Which best describes a biosphere reserve? Options:
(A) A small fenced area for selective breeding (A) 1-d, 2-c, 3-b, 4-a
(B) A model for integrated conservation, combining (B) 1-c, 2-d, 3-b, 4-a
core, buffer, and transition zones (C) 1-b, 2-a, 3-c, 4-d
(C) A single-species captive breeding program (D) 1-a, 2-c, 3-d, 4-b
(D) A commercial farmland for genetically modified

Ans
crops
(B) 1-c, 2-d, 3-b, 4-a


Ans National Parks (1-c) prohibit most human interventions,
(B) A model for integrated conservation, combining focusing on total habitat protection. Wildlife Sanctuaries
core, buffer, and transition zones (2-d) allow certain controlled activities. Sacred Groves
Biosphere reserves aim to reconcile conservation with (3-b) are forest patches protected by local communities
sustainable resource use. They typically have strictly for religious reasons. Ramsar Sites (4-a) designate
protected core areas, a surrounding buffer for limited wetlands of global ecological importance.
human activity, and an outer transition zone where
39. Which best explains the term “endemic species”?
sustainable practices and settlements occur, preserving
biodiversity while supporting local livelihoods. (A) Species widely distributed worldwide
(B) Species that migrate seasonally across continents
37. What is “parthenocarpy” in the context of fruit (C) Species restricted to a particular region or habitat
formation? (D) Species with unlimited genetic variability
(A) Development of fruits after fertilization

Ans
(B) Production of seeds without fertilization
(C) Formation of seedless fruits without fertilization (C) Species restricted to a particular region or habitat
(D) Fusion of multiple ovules into one seed Endemic species occur only in specific geographic
locales, often due to unique evolutionary histories or


Ans environmental constraints. Their limited distribution
(C) Formation of seedless fruits without fertilization makes them particularly vulnerable to habitat loss and
Parthenocarpy is the process in which fruits form other anthropogenic pressures.
without the occurrence of fertilization, resulting in
40. Why is ex situ conservation (e.g., seed banks) important
seedless varieties. This phenomenon can be induced
hormonally or occur naturally in certain species, for rare plant species?
offering consumer advantages like easy consumption. (A) It ensures species remain in the wild exclusively
(B) It eliminates all need for in situ conservation
38. Match the following conservation strategies in Column (C) It preserves genetic material in controlled facilities,
I with their descriptions in Column II: safeguarding against extinction
(D) It halts reproduction of those species entirely
Column I Column II
1. National Parks a. Wetland areas of

Ans
international importance (C) It preserves genetic material in controlled facilities,
2. Wildlife b. Privately or communally safeguarding against extinction
Sanctuaries protected forest patches Ex situ conservation measures, such as seed banks or
with religious significance botanical gardens, maintain living specimens or genetic
resources outside natural habitats. This provides a safety

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 PRACTICE PAPER 16

net in case in situ populations collapse, helping protect (A) It limits the variety of species that can coexist
rare or threatened species from permanent loss. (B) It reduces the plant’s chance of successful
reproduction


Direction :Carefully read the case study provided and then (C) It increases the probability of seeds reaching
thoroughly answer the subsequent five questions. favorable sites
A group of environmental scientists studied fruit dispersal (D) It prevents pollination altogether
mechanisms in a tropical forest. They noticed certain
plant species produced brightly colored, fleshy fruits with

Ans
sweet pulp. These fruits attracted birds and mammals (C) It increases the probability of seeds reaching
that consumed them, dispersing seeds through droppings favorable sites
away from the parent plant. Meanwhile, other species When many plant species compete for space and
developed lightweight, winged seeds for wind dispersal. resources, employing different dispersal mechanisms
The researchers concluded that diverse strategies evolved (animal ingestion or wind dispersal) helps seeds avoid
to maximize reproductive success in crowded habitats. overcrowding near the parent. It raises the odds that
Conservationists emphasized protecting these forests to some seeds will find optimal conditions for germination
safeguard ecological interactions critical for regeneration and survival.
and biodiversity maintenance.
44. How do lightweight, winged seeds assist wind dispersal?
41. What was the primary animal-mediated seed dispersal (A) By sinking to the bottom of the forest floor
method described? (B) By attaching to large herbivores
(A) Bursting pods scattering seeds (C) By floating in rivers to distant shores
(B) Seeds clinging to passing insects (D) By enabling seeds to be carried by air currents
(C) Birds and mammals eating fleshy fruits and

Ans
dispersing seeds in droppings
(D) Seeds sinking in water to germinate underwater (D) By enabling seeds to be carried by air currents
Wing-like appendages or lightweight structures help


Ans seeds ride air currents, often traveling considerable
(C) Birds and mammals eating fleshy fruits and distances before landing. This type of dispersal ensures
dispersing seeds in droppings genetic mixing across broader geographic ranges and
The passage highlights frugivory, where animals ingest lowers seedling competition near the parent.
fleshy fruits and later excrete seeds elsewhere. This
45. Why do conservationists emphasize protecting these
mutualistic interaction helps plants colonize new areas
while providing food resources for animals, sustaining tropical forests for seed dispersal?
forest biodiversity. (A) Because the fruits are unpalatable to wildlife
(B) To maintain the essential ecological interactions
42. Why do bright colors and sweet pulp help certain fruits that support regeneration
in tropical forests? (C) To discourage any animal involvement in seed
(A) They deter herbivores movement
(B) They ensure seeds remain near the parent plant (D) To accelerate deforestation for urban development
(C) They attract seed-eating animals for dispersal

Ans
(D) They hasten seed desiccation
(B) To maintain the essential ecological interactions that


Ans support regeneration
(C) They attract seed-eating animals for dispersal Protecting the habitat preserves the natural relationships
Eye-catching colors and sweet pulp entice animals to between plants and dispersal agents. These interactions
consume the fruits. As these animals travel, seeds are are vital for forest renewal, biodiversity, and resilience
deposited at distant sites, improving the plant’s chances against environmental changes. Disruption of these
of finding suitable habitats and reducing competition processes can dramatically affect ecological balance.
with the parent plant.


Direction :Carefully read the case study provided and then
43. What is the advantage of having multiple dispersal thoroughly answer the subsequent five questions.
strategies in a crowded tropical habitat? In a region plagued by repeated mosquito-borne
infections, local health authorities introduced biological

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controls by releasing a particular fish species known

Ans

to feed on mosquito larvae in standing water bodies. (C) Eliminating stagnant water sources around homes
Within months, the incidence of mosquito-related Public campaigns aim to reduce mosquito breeding
diseases declined. However, ecologists cautioned that habitats. By discouraging stagnant water collection
the introduced fish could disrupt native aquatic life if (for example in containers or open drains), residents
not carefully managed. They recommended continuous help curb mosquito populations. This complementary
monitoring of fish population levels, water quality, and approach boosts the efficacy of the biological control
disease prevalence. Public awareness campaigns were measures.
also launched to reduce stagnant water accumulation,
tackling the root cause of mosquito breeding. 49. Why is continuous monitoring of fish population levels
critical?
46. What was the main purpose of introducing the fish (A) To encourage the fish to switch diets
species? (B) To ensure the fish can rapidly adapt to land
(A) To enhance local fish markets for profit (C) To prevent the fish from becoming overabundant
(B) To feed on aquatic plants exclusively and harming native species
(C) To reduce mosquito larvae and lower disease (D) To guarantee the fish remain inactive during
occurrence disease outbreaks
(D) To compete with native insect predators


Ans


Ans
(C) To prevent the fish from becoming overabundant
(C) To reduce mosquito larvae and lower disease and harming native species
occurrence A balanced fish population prevents ecological
Releasing larvivorous fish is a biocontrol strategy aimed disruptions. If the introduced fish species proliferates
at minimizing mosquito populations. By consuming uncontrollably, it may deplete resources for native
larval stages, these fish help break the life cycle of species, disrupt food webs, or cause unforeseen
mosquitoes, thus reducing vector-borne diseases in ecological shifts, reversing the benefits of biological
affected communities. control.
47. Why do ecologists urge caution regarding the introduced 50. How does tackling mosquito breeding sites at the root
fish species? address disease prevention?
(A) They believe mosquito populations should increase (A) It forces mosquitoes to shift to new vectors
(B) They fear the fish might become a new snack for (B) It removes the environment needed for mosquito
local predators larvae to develop
(C) The fish could outcompete or disrupt native aquatic (C) It directly kills adult mosquitoes
life (D) It only helps in cold climates
(D) The fish may refuse to feed on mosquito larvae


Ans


Ans
(B) It removes the environment needed for mosquito
(C) The fish could outcompete or disrupt native aquatic larvae to develop
life Mosquitoes require stagnant water to lay eggs and
Introducing non-native species can lead to ecological nurture larvae. Eliminating such water sources disrupts
imbalances if they overconsume resources or prey on the life cycle early, significantly reducing adult mosquito
local species. Monitoring ensures that while controlling populations. This approach, combined with other
mosquito populations, these fish do not harm indigenous control measures, effectively lowers disease incidence.
aquatic organisms or degrade ecosystem stability.


*************
48. Which additional strategy did health authorities
promote alongside biological control?
(A) Widespread introduction of exotic bird species
(B) Creating more stagnant water for fish breeding
(C) Eliminating stagnant water sources around homes
(D) Banning the use of mosquito nets

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 PRACTICE PAPER 17

PRACTICE PAPER 17

1. Which part of a flower typically encloses the female source for the developing embryo. This unique process,
gametophyte during development? exclusive to angiosperms, supports effective embryo
(A) Filament growth, contributing to the evolutionary success of
(B) Style flowering plants.
(C) Ovule
4. Which of the following is NOT part of the male
(D) Petal
reproductive system in humans?


Ans (A) Epididymis
(C) Ovule (B) Vas deferens
The ovule is the specialized structure within the ovary (C) Prostate gland
where the female gametophyte (embryo sac) forms. (D) Fallopian tube
It houses the egg cell and accessory cells, providing

Ans
protection and nourishment. Following fertilization,
it matures into a seed, ensuring propagation and (D) Fallopian tube
continuity of the flowering plant species. The Fallopian tube is found exclusively in the female
reproductive system, where it allows passage of the
2. Which term describes the fusion of two polar nuclei and ovum from the ovary to the uterus. Male structures
a male gamete that gives rise to the endosperm? include the epididymis for sperm maturation, the vas
(A) Double fertilization deferens for sperm transport, and accessory glands such
(B) Triple fusion as the prostate gland.
(C) Syngamy
5. Where does spermatogenesis primarily occur?
(D) Micropyle fusion
(A) Seminal vesicle


Ans (B) Testicular lobules
(B) Triple fusion (C) Seminiferous tubules
Triple fusion is the process in which the male gamete (D) Epididymis head
fuses with two polar nuclei located in the central cell of

Ans
the embryo sac. This event occurs simultaneously with
syngamy in flowering plants. The result is the triploid (C) Seminiferous tubules
endosperm, which provides essential nutrients for the Spermatogenesis is the process of sperm production,
developing embryo. which begins in the seminiferous tubules of the
testes. These tubules provide the environment where
3. In flowering plants, which structure forms immediately spermatogonia proliferate, undergo meiosis, and
after double fertilization and eventually nourishes the differentiate into mature spermatozoa. The epididymis
embryo? later stores and further matures these sperm cells before
(A) Zygote they move along the reproductive tract.
(B) Endosperm
6. Which hormone from the anterior pituitary primarily
(C) Seed coat
(D) Cotyledon stimulates Leydig cells to produce testosterone?
(A) Oxytocin


Ans (B) FSH
(B) Endosperm (C) LH
Double fertilization produces two key products: the (D) Prolactin
zygote and the triploid endosperm. The endosperm

Ans
forms within the embryo sac and serves as a rich nutrient

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(C) LH (D) Copper-T

Luteinizing hormone (LH) targets the Leydig cells

Ans
in the testes, prompting them to synthesize and
secrete testosterone. This androgen is crucial for (C) Condoms
spermatogenesis, masculine secondary sexual While many contraceptive approaches prevent
characteristics, and overall male reproductive function. unintended pregnancies, condoms are uniquely
Follicle-stimulating hormone (FSH) mainly acts on positioned to reduce the transmission risk of sexually
Sertoli cells, while oxytocin and prolactin serve different transmitted infections by physically blocking pathogens.
physiological roles. Methods such as diaphragms, oral pills, and intrauterine
devices primarily prevent conception but do not reliably
7. Arrange the following events of the menstrual cycle in shield against viral or bacterial agents causing STIs.
correct chronological order:
10. Which comparison between Mendelian inheritance and
1. LH surge
2. Menstruation incomplete dominance is CORRECT?
3. Ovulation (A) Mendelian traits always blend, incomplete traits
4. Proliferative phase never do
(A) 2 → 4 → 1 → 3 (B) Mendelian traits show intermediate offspring in F2,
(B) 4 → 2 → 1 → 3 incomplete traits do not
(C) 2 → 1 → 4 → 3 (C) Mendelian traits have distinct phenotypes,
(D) 2 → 3 → 4 → 1 incomplete traits form intermediate phenotypes
(D) Mendelian has 1:1 ratio, incomplete has 2:1 ratio


Ans


Ans
(A) 2 → 4 → 1 → 3
The cycle begins with menstruation (day 1), followed (C) Mendelian traits have distinct phenotypes,
by the proliferative phase as the endometrium incomplete traits form intermediate phenotypes
rebuilds. Rising estrogen levels lead to the LH surge, In typical Mendelian inheritance, dominant and
which triggers ovulation. Thus, the correct order is: recessive traits remain clearly distinguishable. In
Menstruation, Proliferative phase, LH surge, and incomplete dominance, neither allele fully masks the
finally Ovulation. This sequence underlies the typical other, producing an intermediate phenotype. A classic
menstrual cycle pattern. example is the pink F1 flowers from crossing red and
white snapdragons, confirming partial expression of
8. Which structure implants into the uterine wall to both parental allele effects.
establish pregnancy?
11. Which combination of statements about codominance
(A) Morula
(B) Zygote is CORRECT?
(C) Blastocyst 1. Both alleles express fully
(D) Germinal disc 2. One allele completely masks the other
3. ABO blood group inheritance exemplifies


Ans codominance
(C) Blastocyst 4. Codominance produces blended phenotypes
Approximately a week after fertilization, the blastocyst, (A) 1 and 4
a hollow ball of cells with an inner cell mass, attaches (B) 2 and 4
and embeds itself into the endometrium. This process, (C) 1 and 3
known as implantation, initiates the formation of the (D) 2 and 3
placenta and other essential tissues needed to support

Ans
the developing embryo throughout pregnancy.
(C) 1 and 3
9. Which method is most effective in preventing Codominance involves both alleles being equally
transmission of sexually transmitted infections? expressed, as seen with human ABO blood groups,
(A) Diaphragms where IA and IB alleles each manifest in the phenotype
(B) Oral contraceptive pills (type AB). By contrast, incomplete dominance yields
(C) Condoms a blend, and simple dominance involves one allele

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 PRACTICE PAPER 17

overshadowing the other. Thus, statements 1 and 3 are 15. Which triplet codon serves as the START signal in most
correct. organisms?
(A) UAA
12. A female with Turner’s syndrome has which (B) UAG
chromosomal constitution? (C) AUG
(A) XXY (D) UGA
(B) XXX
(C) XO

Ans
(D) XYY (C) AUG


Ans AUG codes for methionine in eukaryotes and serves as
the universal start codon in mRNA, initiating translation
(C) XO at the ribosome. The other codons listed (UAA, UAG,
Turner’s syndrome results from the partial or complete UGA) are stop codons, which signal termination.
absence of one X chromosome in females, leading This strict initiation codon system helps to maintain
to an XO configuration. Affected individuals may consistent open reading frames in protein synthesis.
show short stature, underdeveloped ovaries, and
other characteristic features. Karyotypes such as XXY 16. Which term refers to the evolutionary process leading
(Klinefelter’s), XXX (Triple X), and XYY are distinct to the formation of new species?
chromosomal abnormalities in humans. (A) Speciation
(B) Gene pool
13. Which molecule carries the genetic code from DNA to (C) Genetic drift
the ribosome? (D) Hybrid vigour
(A) rRNA
(B) mRNA

Ans
(C) tRNA (A) Speciation
(D) snRNA Speciation is the process by which distinct lineages


Ans split from a common ancestral population, forming
genetically separate species. Reproductive isolation,
(B) mRNA genetic variations, and evolutionary forces such as
Messenger RNA (mRNA) is synthesized during natural selection or drift contribute to this divergence.
transcription in the nucleus, carrying the genetic Over time, newly formed populations become incapable
instructions from DNA. It travels to the ribosome, of interbreeding with their ancestral group.
where it guides amino acid sequence assembly through
translation. Ribosomal RNA (rRNA) composes 17. Which comparison of gene flow and genetic drift is
ribosomes, while tRNA delivers amino acids. Small CORRECT?
nuclear RNA (snRNA) assists in RNA processing. (A) Both are random processes influencing allele
frequencies
14. Which of the following is NOT directly involved in (B) Gene flow is random, drift is directional
eukaryotic DNA replication? (C) Gene flow is directional, drift is random
(A) DNA helicase (D) Both are directional processes in large populations
(B) RNA polymerase II
(C) DNA polymerase

Ans
(D) Single-strand binding proteins (A) Both are random processes influencing allele


Ans frequencies
Gene flow, the movement of genes between populations,
(B) RNA polymerase II can introduce or remove alleles unpredictably. Genetic
DNA replication involves enzymes such as DNA helicase drift, especially in smaller populations, randomly shifts
to unwind the helix, DNA polymerase to synthesize allele frequencies through chance events. While natural
new strands, and single-strand binding proteins to selection can be directional, gene flow and drift are
stabilize unwound DNA. RNA polymerase II primarily typically random regarding which alleles increase or
transcribes mRNA during gene expression, making decrease in frequency.
it unnecessary for the core mechanism of copying the
eukaryotic genome.

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18. Which set of statements is CORRECT about the Hardy- 21. Which cells in the body are primarily targeted by HIV?
Weinberg principle? (A) Neurons
1. p + q = 1 (B) T-helper lymphocytes
2. p² + 2pq + q² = 1 (C) Erythrocytes
3. Large population size is assumed (D) Platelets
4. Migration regularly disrupts equilibrium

Ans
5. No mutation or selection is assumed
(A) 1, 2, 3, 5 (B) T-helper lymphocytes
(B) 1, 2, 4, 5 HIV targets CD4⁺ T-helper cells, crippling the adaptive
(C) 2, 3, 4, 5 immune response by disrupting cytokine signaling
(D) 1, 3, 4, 5 and overall immunity. This depletion paves the way
for opportunistic pathogens to flourish, progressing


Ans to acquired immunodeficiency syndrome (AIDS).
(A) 1, 2, 3, 5 Neurons, red blood cells, and platelets are not the
The Hardy-Weinberg principle assumes random principal target for HIV’s viral binding.
mating, no migration, no mutation, no selection, and
22. Match each microbe with its application:
large population size. Its core equations are p + q = 1
(allele frequencies) and p² + 2pq + q² = 1 (genotype Column I Column II
frequencies). Migration disrupts equilibrium, but under a. Yeast 1. Biogas production
Hardy-Weinberg, it is ideally assumed absent.
b. Methanogen 2. Bread fermentation
19. Which pathogen causes malaria in humans? c. Aspergillus 3. Citric acid production
(A) Plasmodium vivax d. Azotobacter 4. Nitrogen fixation
(B) Entamoeba histolytica
Options:
(C) Trypanosoma gambiense
(A) a-2, b-1, c-3, d-4
(D) Giardia lamblia
(B) a-1, b-2, c-3, d-4


Ans (C) a-3, b-4, c-2, d-1
(A) Plasmodium vivax (D) a-2, b-4, c-1, d-3
Malaria is commonly caused by various Plasmodium

Ans
species, including P. vivax, P. falciparum, and P.
(A) a-2, b-1, c-3, d-4
malariae. Among these, P. vivax is widespread. It invades
Yeast (Saccharomyces) is widely used for bread
human red blood cells, leading to cyclical fever, anemia,
fermentation. Methanogens generate methane in
and other clinical manifestations. Mosquito vectors
biogas plants. Aspergillus niger produces citric acid
(Anopheles) transmit the parasite between infected and
on an industrial scale. Azotobacter fixes atmospheric
susceptible individuals.
nitrogen, enriching soil fertility. Thus, the correct
20. Which of the following is NOT a viral disease? matching is: yeast → bread fermentation, methanogen
(A) Dengue → biogas, Aspergillus → citric acid, Azotobacter →
(B) Chikungunya nitrogen fixation.
(C) Pneumonia (typical bacterial form)
23. Which microbe is commonly used for producing the
(D) AIDS
antibiotic Penicillin?


Ans (A) Penicillium notatum
(C) Pneumonia (typical bacterial form) (B) Rhizopus stolonifer
Pneumonia in its most classic bacterial presentation (C) Clostridium botulinum
is caused by organisms such as Streptococcus (D) Saccharomyces cerevisiae
pneumoniae, not by viruses. Dengue and chikungunya

Ans
are viral diseases transmitted by mosquitoes. AIDS
(A) Penicillium notatum
results from HIV infection, also viral in origin, affecting
Penicillin, the first major antibiotic discovered by
the immune system and leaving individuals vulnerable
Alexander Fleming, is produced by Penicillium notatum
to opportunistic infections.
molds. This fungus secretes compounds that inhibit

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 PRACTICE PAPER 17

bacterial cell wall synthesis. Other microbes listed serve In agarose gel electrophoresis, DNA fragments
different roles: Rhizopus for bread spoilage, Clostridium (negatively charged because of phosphate groups) travel
botulinum for toxin production, and Saccharomyces toward the positive electrode. Smaller fragments move
cerevisiae for fermentation in baking and brewing. faster through the gel matrix, leading to separation
based on size. Neither gravity, centrifugal force, nor
24. How do biofertilizers help enhance soil fertility? evaporation is relevant to the directional movement of
(A) Secrete root exudates the DNA segments.
(B) Fix atmospheric nitrogen
(C) Absorb surplus nitrates 27. Which combination is TRUE regarding polymerase
(D) Oxidize soil minerals chain reaction (PCR)?


Ans 1. Amplifies specific DNA sequences
2. Requires RNA polymerase
(B) Fix atmospheric nitrogen 3. Uses heat-stable Taq DNA polymerase
Biofertilizers contain microorganisms, such as 4. Operates through repeated cycles of denaturation,
Rhizobium, Azotobacter, and Azospirillum, capable annealing, extension
of converting atmospheric nitrogen into usable forms. (A) 1 and 2
This process enriches soil fertility without the overuse (B) 2 and 4
of chemical fertilizers. Enhanced nutrient levels (C) 1, 3, and 4
improve plant growth and sustainability. Root exudates (D) 1, 2, and 3
and mineral oxidation are different mechanisms not
primarily classified as biofertilization.

Ans
(C) 1, 3, and 4
25. Assertion (A) : Restriction enzymes cut DNA at specific PCR amplifies targeted DNA fragments using Taq DNA
sites. polymerase, a heat-stable enzyme. The reaction involves
Reason (R) : They are also called molecular scissors cyclic steps: denaturation at high temperature, primer
used in recombinant DNA technology. annealing at lower temperature, and extension. RNA
(A) Both Assertion and Reason are true, and Reason is polymerase is not typically involved in PCR, as it is
the correct explanation of Assertion. used for transcribing RNA rather than amplifying DNA
(B) Both Assertion and Reason are true, but Reason is sequences.
not the correct explanation.
(C) Assertion is true, Reason is false. 28. Which of the following is NOT a typical benefit of
(D) Assertion is false, Reason is true. genetically modified (GM) crops?


Ans (A) Enhanced pest resistance
(B) Increased yields
(A) Both Assertion and Reason are true, and Reason is (C) Reduced pesticide usage
the correct explanation of Assertion. (D) Spontaneous generation of new species
Restriction enzymes recognize short palindromic DNA
sequences and cleave precisely, acting like molecular

Ans
scissors. Their specificity and controlled cutting of DNA (D) Spontaneous generation of new species
fragments make them indispensable for recombinant GM crops are engineered to boost pest resistance,
DNA technology. Consequently, the Reason directly tolerance to environmental stresses, and often
explains why they are often termed molecular scissors higher yields. Consequently, pesticide requirements
in genetic engineering applications. can sometimes decrease. However, “spontaneous
generation” of new species is not an established effect of
26. During the separation of DNA fragments in agarose gel genetic modification. New crop varieties arise through
electrophoresis, fragments move primarily due to: breeding or engineering, not spontaneous evolutionary
(A) Charge differences jumps.
(B) Gravity
(C) Centrifugal force 29. Which organism is engineered to produce the Bt toxin
(D) Evaporation rates for pest-resistant crops?


Ans (A) Bacillus subtilis
(B) Bacillus thuringiensis
(A) Charge differences

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(C) Agrobacterium tumefaciens 32. In a population growth curve, which phase immediately
(D) Escherichia coli follows the lag phase in an ideal environment?


Ans (A) Stationary phase
(B) Exponential phase
(B) Bacillus thuringiensis (C) Decline phase
Bacillus thuringiensis synthesizes proteins toxic to (D) Equilibrium phase
certain insect larvae. These genes, known as Bt genes,
are introduced into plants to confer insect resistance.

Ans
Agrobacterium tumefaciens is frequently used as a (B) Exponential phase
vector for plant gene transfer, but Bt toxins specifically After acclimatizing during the lag phase, populations
come from Bacillus thuringiensis, not from other enter a rapid expansion known as the exponential or
bacterial species. log phase, where resources are plentiful and growth
rate is maximal. Eventually, limiting factors slow the
30. Which of these biotechnological interventions is used to rate, leading to a stationary phase. If conditions worsen,
correct a genetic defect by replacing a faulty gene with a population decline occurs. Equilibrium implies stable
functional one? population conditions.
(A) Gene therapy
(B) Stem cell therapy 33. Which statements about population attributes are
(C) Tissue culture TRUE?
(D) Clonal propagation 1. Birth rate affects population size


Ans 2. Age distribution describes proportions of age
groups
(A) Gene therapy 3. Carrying capacity is negligible
Gene therapy targets the genetic root cause of inherited 4. Death rate influences population size
disorders by introducing or replacing dysfunctional (A) 1, 2, and 4
genes with functional equivalents. It can use viral or (B) 1, 3, and 4
non-viral vectors to deliver healthy copies into the (C) 2, 3, and 4
patient’s cells. Stem cell therapy, tissue culture, and clonal (D) 1 and 2 only
propagation are distinct but separate biotechnological
techniques.

Ans
(A) 1, 2, and 4
31. Match each term with the correct description: Population attributes include birth rate, death rate, and
Column I Column II age distribution, each shaping overall demographics.
a. Mutualism 1. One benefits, other harmed Birth rate and death rate directly influence population
size, and the age structure reveals reproduction
b. Parasitism 2. Both benefit
potential. Carrying capacity is not negligible; rather, it
c. Competition 3. Both harmed limits population growth. Thus, statements 1, 2, and 4
d. Predation 4. One benefits, other killed are correct.
Options:
34. Match each term with the correct description:
(A) a-2, b-1, c-3, d-4
(B) a-3, b-4, c-1, d-2 Column I Column II
(C) a-2, b-3, c-1, d-4 a. Primary 1. Breakdown of complex
(D) a-1, b-2, c-4, d-3 productivity organic matter


Ans b. Decomposition 2. Amount of energy fixed
(A) a-2, b-1, c-3, d-4 by producers
In mutualism, both partners benefit. Parasitism benefits c. Biomass 3. Graphical representation
the parasite at the host’s expense. Competition often pyramid of mass
harms both species involved as resources become Options:
limited. Predation benefits the predator, which kills and (A) a-1, b-2, c-3
consumes the prey. Thus, the correct matches are a-2, (B) a-2, b-1, c-3
b-1, c-3, and d-4. (C) a-3, b-1, c-2

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 PRACTICE PAPER 17

(D) a-2, b-3, c-1 c. National 3. Large wildlife protection

Ans parks areas
(B) a-2, b-1, c-3 Options:
Primary productivity is the rate at which producers (A) a-1, b-2, c-3
fix energy as biomass. Decomposition refers to the (B) a-2, b-1, c-3
breakdown of complex organic materials into simpler (C) a-3, b-1, c-2
substances by decomposers. A biomass pyramid visually (D) a-1, b-3, c-2
depicts the mass of living organisms at each trophic

Ans
level. Thus, a-2, b-1, c-3 is the correct match.
(B) a-2, b-1, c-3
35. Which of the following is NOT a typical trophic level in Sacred groves are patches of forest or natural habitats
an ecosystem? preserved by communities for religious or cultural
(A) Primary producers reasons. The Red Data Book compiles lists of threatened
(B) Primary consumers species. National parks are designated areas for wildlife
(C) Secondary consumers conservation and habitat protection. Hence, a-2, b-1,
(D) Parasites as apex decomposers and c-3 accurately match each measure’s description.


Ans 38. Which combination accurately represents major causes
(D) Parasites as apex decomposers of biodiversity loss?
Ecosystems typically include producers (plants), 1. Habitat destruction
primary consumers (herbivores), secondary consumers 2. Overexploitation
(carnivores), and sometimes tertiary consumers. 3. Pollinator increase
Parasites feed on hosts but do not form the apex 4. Introduction of invasive species
decomposer level. Decomposers (fungi, bacteria) 5. Climate change
recycle nutrients, while parasites represent a separate (A) 1, 2, 3, 4
ecological niche. Hence, the idea of parasites as apex (B) 1, 2, 4, 5
decomposers is incorrect. (C) 2, 3, 4, 5
(D) 1, 3, 4, 5
36. Energy flow in an ecosystem is described as:


Ans
(A) Cyclic and reversible
(B) One-way and non-cyclic (B) 1, 2, 4, 5
(C) Primarily stored in top consumers Biodiversity loss stems from habitat destruction,
(D) Mostly lost at producer level overexploitation of species for resources, alien species
invasions that disrupt native ecosystems, and changes


Ans
in climate that alter habitats. Increasing pollinators
(B) One-way and non-cyclic typically supports biodiversity rather than endangering
Energy captured by producers from sunlight moves it. Thus, the correct causes of biodiversity decline are
unidirectionally through consumers to decomposers, habitat destruction, overuse, invasives, and climate
with most lost as heat at each trophic transfer. This path change.
is non-cyclic because energy cannot be reused once
lost to the environment. Nutrients, in contrast, cycle 39. Arrange these conservation methods from older to
through ecosystems, but energy follows a one-way, more recent adoption:
diminishing flow. 1. Sacred groves
2. Biosphere reserves
37. Match the conservation measure with its description: 3. Wildlife sanctuaries
Column I Column II 4. Biodiversity hotspots concept
(A) 1 → 3 → 2 → 4
a. Sacred groves 1. Document endangered
(B) 3 → 1 → 4 → 2
species
(C) 1 → 2 → 3 → 4
b. Red Data 2. Traditional community- (D) 1 → 4 → 3 → 2
Book protected areas


Ans

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page 172 CUET UG Biology

(A) 1 → 3 → 2 → 4 41. Which contraceptive method discussed is most effective

Sacred groves are ancient community traditions. at reducing STI transmission?
Wildlife sanctuaries emerged under formal conservation (A) Oral pills
policies. Biosphere reserves gained traction later, (B) Contraceptive patch
incorporating scientific management and human (C) Intrauterine device
involvement. The biodiversity hotspot concept was (D) Condom
popularized even more recently. Thus, from oldest to

Ans
newest: sacred groves, wildlife sanctuaries, biosphere
reserves, and hotspot identification. (D) Condom
Condoms offer a physical barrier, reducing the exchange
40. Assertion (A) : Vaccination stimulates the immune of infectious fluids during intercourse. Consequently,
system to produce memory cells. they provide dual protection—against both unintended
Reason (R) : Memory cells help in faster secondary pregnancy and sexually transmitted infections. While
immune responses. other contraceptive methods may effectively prevent
(A) Both Assertion and Reason are true, and Reason is pregnancy, they do not typically shield against viral or
the correct explanation. bacterial STIs, making condoms a unique option.
(B) Both Assertion and Reason are true, but Reason is
42. According to the scenario, why is collaborative
not the explanation.
(C) Assertion is true, Reason is false. awareness essential?
(D) Assertion is false, Reason is true. (A) Promotes reliance on myths
(B) Increases confusion among users


Ans (C) Leads to more informed decisions
(A) Both Assertion and Reason are true, and Reason is (D) Reduces community health resources
the correct explanation.

Ans
Vaccines contain attenuated or inactivated antigens,
priming the immune system to create memory cells. (C) Leads to more informed decisions
These cells recognize re-exposure to the same pathogen Community collaboration dispels misconceptions and
and generate a faster, more robust defense. Hence, ensures accurate information on reproductive health
the production of memory cells directly explains is shared consistently. Informed decisions result when
how vaccination leads to quicker secondary immune individuals understand contraceptive options, STI
responses. prevention measures, and the importance of regular
medical guidance. This teamwork fosters responsible


Direction :Carefully read the case study provided and then family planning and better overall health outcomes,
thoroughly answer the subsequent five questions. rather than confusion or resource depletion.
Raj and Priya are final-year college students engaged in
community health work. They visit a local clinic where 43. Which statement best reflects the role of workshops in
many young couples inquire about birth control methods. this context?
Observing widespread uncertainty, Raj and Priya (A) They discourage communication
decide to conduct workshops on contraception, sexually (B) They promote isolation
transmitted infections (STIs), and general reproductive (C) They spread unreliable data
well-being. In collaboration with healthcare professionals, (D) They enhance understanding of reproductive
they emphasize the importance of safe sexual practices, health
the correct use of condoms, and the need for regular

Ans
check-ups. They also discuss myths surrounding oral (D) They enhance understanding of reproductive health
contraceptives and highlight the significance of preventing Workshops bring professionals and community
STIs like HIV. Additionally, they encourage both men members together, providing verified information and
and women to actively participate in family planning interactive learning on contraception, STIs, and overall
decisions, demonstrating how collective awareness can reproductive care. This environment boosts clarity,
significantly enhance reproductive health outcomes in dispels harmful myths, and enables open discussion.
their community. Consequently, workshop participants gain practical

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 PRACTICE PAPER 17

knowledge and motivation to adopt safe, effective health waste management while producing environmentally
practices for themselves and others. friendly energy and enhancing soil fertility, exemplifying
how microbes can revolutionize agricultural practices.
44. What was one identified benefit of encouraging joint
participation of men and women in family planning? 46. Which group of bacteria is primarily responsible for
(A) Causes increased gender tension methane production in the biogas plant?
(B) Promotes mutual responsibility (A) Sulfur bacteria
(C) Diminishes women’s decision-making (B) Nitrogen-fixing bacteria
(D) Eliminates medical requirements (C) Methanogens


Ans (D) Thermophiles

(B) Promotes mutual responsibility

Ans

Involving both partners in reproductive planning (C) Methanogens
can balance decision-making and ensure shared Methanogenic bacteria, such as Methanobacterium,
accountability. Men and women who equally degrade organic matter under anaerobic conditions.
comprehend methods and needs are more likely to They produce methane as a metabolic byproduct. Sulfur
adopt healthy behaviors, reduce gender disparities, and bacteria, nitrogen-fixers, and thermophiles function
support each other’s well-being. This partnership fosters differently. For instance, nitrogen-fixers incorporate
greater satisfaction and effectiveness in family planning atmospheric nitrogen, and thermophiles thrive at
measures. high temperatures but are not necessarily methane-
producers, making methanogens unique in biogas
45. Which rationale supports discussing myths regarding generation.
oral contraceptives?
(A) To reinforce misconceptions 47. What environmental benefit is achieved by using the
(B) To limit patient autonomy resulting slurry as a biofertilizer?
(C) To clarify side effects and accuracy (A) Increases chemical runoff
(D) To promote secrecy in usage (B) Reduces soil nutrient levels


Ans (C) Enhances soil fertility
(D) Raises greenhouse gas emissions
(C) To clarify side effects and accuracy
Myths around oral contraceptives can deter proper

Ans
usage or fuel fears about nonexistent risks. Educating (C) Enhances soil fertility
individuals on actual mechanisms, side effects, and The digested slurry from anaerobic fermentation retains
overall reliability helps them make sound, confident valuable nutrients and organic matter. When applied
decisions. Eliminating confusion promotes adherence to fields, it enriches soil structure, improves water
and safe use, ensuring that misinformation does not retention, and provides essential nutrients for plants.
overshadow the true benefits of contraceptive pills. This eco-friendly option replaces or reduces synthetic
fertilizers, thus limiting chemical runoff and promoting


Direction :Carefully read the case study provided and then sustainable, circular farming practices.
thoroughly answer the subsequent five questions.
At the Green Valley Dairy Farm, a pilot biogas plant was 48. How does utilizing methane as a fuel at the dairy farm
installed to manage the farm’s organic waste and generate promote sustainability?
renewable energy. Cattle dung, along with leftover (A) It relies solely on synthetic inputs
feed, is fed into a large fermentation tank populated by (B) It emits excessive carbon monoxide
methanogenic bacteria. These microorganisms break (C) It diverts organic waste from landfills
down the waste anaerobically, producing a mixture of (D) It prevents oxygen from reaching the soil
methane and carbon dioxide. The methane is collected

Ans
and utilized as a clean-burning fuel for heating and
cooking. Farm workers notice that the digested slurry (C) It diverts organic waste from landfills
from the tank also works as a potent biofertilizer. Surplus Converting farm waste to biogas prevents organic
gas is occasionally sold to nearby facilities, boosting local material from decomposing in landfills, where it would
sustainability efforts. This integrated approach addresses release methane into the atmosphere without energy
recovery. Harnessing methane as fuel efficiently captures

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page 174 CUET UG Biology

and utilizes this greenhouse gas, reducing reliance on

fossil fuels while offering a cleaner, renewable resource
that supports sustainable operations.

49. Which statement best explains why surplus gas sales

benefit local facilities?
(A) It severely pollutes local water sources
(B) It supplies an additional clean energy source
(C) It creates an unregulated market for fertilizers
(D) It undermines local sustainability


Ans
(B) It supplies an additional clean energy source
Excess biogas delivered to nearby facilities presents an
economical, eco-friendly alternative to conventional
fuels like coal or oil. This extends the positive
environmental impact beyond the farm, supporting a
regional shift toward renewable energy. Moreover, local
establishments benefit from reduced costs and fewer
harmful emissions linked to fossil fuels.

50. Why is this integrated biogas model an example of eco-

friendly waste management?
(A) It promotes continuous deforestation
(B) It relies on untested chemicals
(C) It combines waste disposal with energy production
(D) It discards nutrient recycling


Ans
(C) It combines waste disposal with energy production
Converting farm waste into biogas not only manages
organic byproducts but also produces a renewable fuel,
cutting reliance on non-renewable energy. This closed-
loop approach recycles nutrients back to the soil in
the form of slurry, minimizing environmental impact.
Consequently, it is an effective synergy of waste control
and energy generation.

*************

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 PRACTICE PAPER 18

PRACTICE PAPER 18

1. Which structure in angiosperms houses the male wall can thicken, forming the pericarp that protects the
gametophyte? seeds. The style and stigma facilitate pollen reception
(A) Petal but do not directly develop into fruits.
(B) Stamen
4. Which of the following does NOT secrete a fluid
(C) Ovary
(D) Sepal component that becomes part of semen?
(A) Seminal vesicle


Ans (B) Prostate gland
(B) Stamen (C) Bulbourethral gland
In flowering plants, the stamen is the male reproductive (D) Epididymis
organ consisting of anthers and filaments. Pollen grains

Ans
develop in the anthers, each pollen grain containing the
male gametophyte. Petals and sepals are floral whorls (D) Epididymis
assisting pollinator attraction and protection, while the The epididymis primarily stores and matures sperm
ovary encloses the female gametophyte. but does not significantly contribute fluid secretions.
Seminal vesicles, prostate gland, and bulbourethral
2. Which term describes plants that produce seeds without (Cowper’s) glands release fluids that nourish and
fertilization? protect sperm, forming semen. While the epididymis
(A) Parthenogenesis produces minor secretions for sperm maturation, it is
(B) Apomixis not recognized as a main fluid contributor.
(C) Polyembryony
5. Which comparison of spermatogenesis and oogenesis is
(D) Androecium
CORRECT?


Ans (A) Both produce four viable gametes
(B) Apomixis (B) Oogenesis occurs continuously, spermatogenesis is
Apomixis is a form of asexual seed formation bypassing cyclical
traditional fertilization. The resulting progeny are (C) Spermatogenesis produces many sperm, oogenesis
genetically identical to the parent. Parthenogenesis yields one ovum
refers to development of an egg without fertilization in (D) Neither process involves hormonal control
certain animals, while polyembryony involves multiple

Ans
embryos in one seed. Androecium designates the
collective male parts of a flower. (C) Spermatogenesis produces many sperm, oogenesis
yields one ovum
3. Which structure typically develops into the fruit after In human males, one primary spermatocyte typically
fertilization? yields four haploid spermatozoa, whereas one primary
(A) Ovary oocyte ultimately produces one mature ovum due to
(B) Ovule unequal cytoplasmic divisions. Spermatogenesis is
(C) Style continuous, while oogenesis proceeds with significant
(D) Stigma pauses. Both are controlled by hormones, so the correct


Ans distinction pertains to gamete quantity per meiotic
event.
(A) Ovary
In angiosperms, the ovary encloses the ovules and 6. Which process releases the ovum from the ovary into
matures into the fruit following fertilization. Each the Fallopian tube?
fertilized ovule transforms into a seed, while the ovary (A) Implantation

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page 176 CUET UG Biology

(B) Ovulation

Ans

(C) Fertilization (C) Syphilis
(D) Cleavage Syphilis is caused by the bacterium Treponema


Ans pallidum, transmitted primarily through sexual contact.
Characterized by distinct stages, its early presentation
(B) Ovulation
may include painless ulcers (chancres). Gonorrhea
Ovulation is the process wherein a mature ovarian
is caused by Neisseria gonorrhoeae, chlamydia by
follicle ruptures, releasing a secondary oocyte into the
Chlamydia trachomatis, and herpes typically by Herpes
Fallopian tube. If fertilization follows, cleavage occurs to
simplex virus types 1 or 2.
form an embryo, which may later implant in the uterine
lining. The process is orchestrated by rising LH levels 10. Assertion (A) : Haemophilia is more common in males.
during the menstrual cycle. Reason (R) : Females require two copies of the mutant
allele, while males need only one on the X chromosome.
7. Which term refers to the voluntary termination of a
(A) Both true, Reason is correct explanation
pregnancy for medical or personal reasons?
(B) Both true, but Reason is not correct explanation
(A) Infertility
(C) Assertion true, Reason false
(B) Miscarriage
(D) Assertion false, Reason true
(C) Medical termination of pregnancy (MTP)
(D) Abstinence

Ans

Ans (A) Both true, Reason is correct explanation

Haemophilia is an X-linked recessive disorder, so a male
(C) Medical termination of pregnancy (MTP)
with one defective allele on his X chromosome expresses
MTP, commonly known as abortion, is the deliberate
the condition. In contrast, females must inherit two
ending of a pregnancy through medical or surgical
defective alleles (one on each X) to manifest symptoms.
means. Miscarriage is an unintentional loss of
Consequently, the disorder is statistically more frequent
pregnancy. Infertility indicates the inability to conceive
in males, precisely matching the stated reason.
or carry a pregnancy. Abstinence involves refraining
from sexual activity. Thus, MTP specifically addresses 11. Which of the following does NOT align with Mendel’s
intentional pregnancy termination. laws?
(A) Independent assortment
8. Which is the safest recommended way to prevent both
(B) Dominance
pregnancy and STIs?
(C) Segregation
(A) Rhythm method
(D) Blending inheritance
(B) Surgical sterilization
(C) Condom use

Ans
(D) Oral contraceptives (D) Blending inheritance


Ans Mendelian genetics emphasizes discrete inheritance
of traits via dominant and recessive alleles. Traits
(C) Condom use
do not irreversibly blend but segregate and assort
Condoms block sperm entry into the reproductive tract
independently. Mendel’s laws include dominance,
and create a barrier against pathogens that cause sexually
segregation, and independent assortment, rejecting
transmitted infections. Oral contraceptives, sterilization,
the blending inheritance concept that postulates
or timing-based methods primarily prevent pregnancy
partial, irreversible fusion of parental characteristics in
but offer limited or no STI protection. Correct and
offspring.
consistent condom use remains the best dual-protection
method. 12. Question 12. Which cross outcome illustrates
codominance in human ABO blood groups?
9. Which infection is a common sexually transmitted
(A) IAIO × IBIO producing type O offspring
disease caused by Treponema pallidum?
(B) IAIO × IAIO producing all type A offspring
(A) Gonorrhea
(C) IAIB × IAIB producing type AB offspring
(B) Chlamydia
(D) IOIO × IOIO producing type A offspring
(C) Syphilis
(D) Herpes

Ans

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 PRACTICE PAPER 18

(C) IAIB × IAIB producing type AB offspring DNA helicase unwinds the double helix, separating
In codominance, both alleles fully express in the the two strands by breaking hydrogen bonds between
phenotype, as seen in the AB blood group (IA and base pairs. DNA polymerase then builds new strands.
IB). Two IAIB parents can produce IAIB offspring, DNA ligase joins Okazaki fragments on the lagging
who display both antigen A and antigen B. Other strand, and topoisomerase relieves supercoiling tension.
combinations represent different ABO outcomes but Helicase’s unwinding action initiates replication forks
may not demonstrate codominant expression as AB for replication progression.
does.
16. Arrange the events of gene expression in eukaryotes in
13. Which type of RNA brings amino acids to the ribosome correct order:
during protein synthesis? 1. mRNA processing
(A) mRNA 2. Transcription
(B) tRNA 3. Translation
(C) rRNA 4. Protein folding
(D) hnRNA (A) 2 → 1 → 3 → 4


Ans (B) 1 → 2 → 3 → 4
(C) 3 → 2 → 1 → 4
(B) tRNA (D) 2 → 3 → 1 → 4
Transfer RNA (tRNA) ferries specific amino acids to the
ribosome, matching codons on mRNA via its anticodon

Ans
loop. Messenger RNA (mRNA) provides the genetic (A) 2 → 1 → 3 → 4
template, ribosomal RNA (rRNA) forms the core of the Gene expression starts with transcription of DNA into a
ribosome, and heterogeneous nuclear RNA (hnRNA) is primary RNA transcript, followed by mRNA processing
the precursor to mature mRNA in eukaryotes. (splicing, capping, polyadenylation). The mature mRNA
is then translated into a polypeptide at ribosomes.
14. Which comparison of DNA and RNA is CORRECT? Finally, post-translational protein folding occurs,
(A) DNA is mostly single-stranded, RNA is double- generating a functional protein. Thus, transcription →
stranded mRNA processing → translation → protein folding.
(B) DNA has thymine, RNA has uracil
(C) DNA is found only in cytoplasm, RNA only in 17. What term describes a group of interbreeding
nucleus individuals occupying a particular area?
(D) Both contain ribose sugar (A) Community


Ans (B) Population
(C) Ecosystem
(B) DNA has thymine, RNA has uracil (D) Biosphere
Deoxyribonucleic acid (DNA) uses thymine, whereas
ribonucleic acid (RNA) employs uracil in place of

Ans
thymine. Generally, DNA is double-stranded and (B) Population
primarily resides in the nucleus, while RNA is often A population comprises members of a single species
single-stranded and can be found in both cytoplasm inhabiting a defined area, sharing a common gene pool.
and nucleus. DNA contains deoxyribose, whereas RNA Communities include multiple populations, ecosystems
contains ribose sugar. encompass communities and their abiotic environment,
and the biosphere is the global sum of all ecosystems.
15. Which enzyme is responsible for unzipping the DNA Thus, a population is a distinct level of biological
double helix during replication? organization.
(A) DNA ligase
(B) DNA polymerase 18. Assertion (A) : Natural selection favors traits increasing
(C) DNA helicase survival.
(D) Topoisomerase Reason (R) : Beneficial traits tend to proliferate in


Ans subsequent generations.
(A) Both true, Reason is correct explanation
(C) DNA helicase (B) Both true, but Reason not correct explanation

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page 178 CUET UG Biology

(C) Assertion true, Reason false (D) Plasmodium falciparum

(D) Assertion false, Reason true

Ans


Ans (A) Rhinovirus
(A) Both true, Reason is correct explanation The common cold is most frequently caused by
Natural selection acts on heritable variations that rhinoviruses, targeting the upper respiratory tract.
enhance fitness. Individuals possessing advantageous Although other viruses (like coronaviruses) can cause
traits are more likely to survive and reproduce, thus similar symptoms, rhinoviruses remain the predominant
passing on those beneficial genes. Over multiple culprits. HIV causes AIDS, Varicella-zoster virus leads
generations, these traits become more prevalent. Hence, to chickenpox/shingles, and Plasmodium falciparum is
the Reason directly explains why natural selection a parasitic protozoan responsible for malaria.
ultimately favors certain traits.
22. Which type of immune response involves T-lymphocytes
19. Which event is a classic example of adaptive radiation? directly attacking infected cells?
(A) Hardy-Weinberg equilibrium (A) Humoral immunity
(B) Variation in codominance (B) Innate immunity
(C) Darwin’s finches on Galápagos Islands (C) Cell-mediated immunity
(D) Gradual changes in population size (D) Passive immunity


Ans

Ans
(C) Darwin’s finches on Galápagos Islands (C) Cell-mediated immunity
Adaptive radiation occurs when a single ancestral species Cell-mediated immunity is driven by T-cells,
diversifies into multiple specialized forms. Darwin’s which recognize and destroy virus-infected or
finches exemplify this, with beaks adapted to different aberrant cells. This differs from humoral immunity,
food sources on the Galápagos. Hardy-Weinberg mediated by antibodies produced by B-cells. Innate
equilibrium concerns constant allele frequencies, immunity includes nonspecific defenses present
codominance pertains to gene expression, and gradual from birth, and passive immunity involves receiving
population changes lack the rapid divergence typical of preformed antibodies through maternal transfer or
adaptive radiations. immunoglobulin injections.

20. Which statements accurately describe genetic drift? 23. Which comparison of active and passive immunity is
1. Happens by chance CORRECT?
2. Stronger in large populations (A) Active immunity is immediate, passive immunity
3. Can cause allele fixation takes time
4. Always enhances fitness (B) Active immunity is short-lived, passive immunity
(A) 1 and 3 is long-lived
(B) 2 and 4 (C) Active immunity often arises from vaccination,
(C) 1, 3, and 4 passive immunity from antibody transfer
(D) 1 and 2 (D) Both forms require direct pathogen contact


Ans

Ans
(A) 1 and 3 (C) Active immunity often arises from vaccination,
Genetic drift is a random fluctuation of allele passive immunity from antibody transfer
frequencies, most pronounced in small populations, Active immunity develops when the body generates
not large ones. It can lead to fixation or loss of alleles its own antibodies upon exposure to an antigen (e.g.,
by chance, irrespective of their impact on fitness. Thus, via vaccine or natural infection). In passive immunity,
while it happens by chance (1) and can cause fixation externally produced antibodies are administered (e.g.,
(3), it does not guarantee fitness. maternal IgG, immunoglobulin injections). Active
immunity tends to be longer-lasting, whereas passive
21. Which infectious agent primarily causes common cold? immunity confers immediate but temporary protection.
(A) Rhinovirus
(B) HIV 24. Which term denotes microorganisms that increase soil
(C) Varicella-zoster virus nutrients by fixing atmospheric nitrogen?

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 PRACTICE PAPER 18

(A) Biocontrol agents (B) Restriction endonuclease

(B) Nitrogen fixers (C) DNA polymerase
(C) Pathogens (D) RNA polymerase
(D) Fermenters

Ans


Ans (A) Reverse transcriptase
(B) Nitrogen fixers Reverse transcriptase transcribes RNA back into DNA,
Nitrogen-fixing microbes, like Rhizobium or a critical step when constructing complementary DNA
Azotobacter, convert inert atmospheric nitrogen into (cDNA) libraries from eukaryotic mRNA. Restriction
ammonia or related compounds, thereby enriching endonucleases cut DNA at specific sites, while standard
soil. Biocontrol agents combat pests, pathogens cause DNA polymerases replicate DNA from a DNA template.
diseases, and fermenters transform substrates into acids RNA polymerase synthesizes RNA from DNA, not the
or alcohol. Hence, microbes that capture atmospheric reverse.
nitrogen for plants are collectively referred to as nitrogen
28. Which term describes the process of introducing
fixers.
recombinant DNA into a host cell?
25. Which is NOT a typical application of microbes in (A) Transcription
industry? (B) Transformation
(A) Antibiotic production (C) Translation
(B) Yogurt formation (D) Conjugation
(C) Sewage treatment

Ans
(D) Creating nuclear fuels
(B) Transformation


Ans Transformation involves the uptake of external DNA—
(D) Creating nuclear fuels often a plasmid—by a host cell, allowing the newly
Microbes commonly yield antibiotics (e.g., penicillin), introduced genetic material to replicate and express.
ferment dairy products (e.g., yogurt), and aid in sewage Transcription is the creation of RNA from DNA,
treatment by decomposing organic waste. However, translation synthesizes proteins from mRNA, and
producing nuclear fuels is entirely different and involves conjugation is a bacterial process of direct DNA transfer
processes unrelated to microbial fermentation or between cells.
enzymatic pathways. Microorganisms play no direct
29. Assertion (A) : Plasmids are widely used as cloning
role in generating nuclear-based energy sources.
vectors.
26. Which method is used in sewage treatment to reduce Reason (R) : Plasmids can carry large fragments of
the biological oxygen demand (BOD)? DNA, exceeding 200 kilobases.
(A) Excess chlorine addition (A) Both true, Reason correct explanation
(B) Microbial digestion in aeration tanks (B) Both true, but Reason not correct explanation
(C) Only filtration through sand (C) Assertion true, Reason false
(D) Thermal incineration (D) Assertion false, Reason true


Ans

Ans
(B) Microbial digestion in aeration tanks (C) Assertion true, Reason false
During secondary treatment, bacteria in aeration Plasmids make effective cloning vectors due to their
tanks consume organic matter in wastewater, thereby ability to replicate independently and carry selectable
lowering BOD. Chlorination serves disinfection, while markers. However, standard plasmid vectors do not
sand filtration removes larger particulates. Thermal typically accommodate extremely large DNA inserts
incineration is more relevant for solid waste. Thus, (only tens of kilobases). Larger DNA fragments may
microbes in aeration tanks significantly reduce organic require specialized vectors (cosmids, BACs). Therefore,
pollutants responsible for elevated BOD levels. the assertion is correct, but the reason is false.

27. Which enzyme synthesizes DNA from an RNA template, 30. Bt toxin in GM crops primarily helps control:
used in cDNA library construction? (A) Pathogenic viruses
(A) Reverse transcriptase (B) Insect pests

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(C) Weed overgrowth these modified cells through tissue culture yields a
(D) Fungal spores complete transgenic plant. Thus, the steps are: gene


Ans isolation, vector insertion, transformation, plant
regeneration.
(B) Insect pests
Bacillus thuringiensis (Bt) toxin is lethal to specific 33. Which statements about GM crops are TRUE?
insects, particularly caterpillars and beetle larvae, by 1. Require fewer chemical pesticides
disrupting their gut lining. Viruses, weeds, and fungi 2. 35. Always reduce yields
may require other control measures. Bt-engineered 3. Undergo biosafety checks
crops produce the toxin within their tissues, reducing 4. Enable possible nutritional enhancements
the need for chemical insecticides and lowering (A) 1 and 3
environmental impact. (B) 2 and 4
(C) 1, 3, and 4
31. Match each biotechnology application with its example: (D) 1, 2, and 3
Column I Column II

Ans
a. Gene therapy 1. Curing hereditary disorders (C) 1, 3, and 4
b. Transgenic 2. Producing human proteins Genetically modified crops frequently lower insecticide
animals in livestock usage (1) and pass stringent biosafety testing (3). They
c. Bt crops 3. Insect resistance can also be nutritionally enhanced (Golden Rice,
Options: for instance) (4). However, they do not inherently
(A) a-1, b-3, c-2 reduce yields; some improve productivity under
(B) a-2, b-1, c-3 specific conditions. Therefore, statement 2 is generally
(C) a-1, b-2, c-3 inaccurate for GM technology.
(D) a-3, b-2, c-1 34. Which interaction involves one species benefiting while


Ans the other is unaffected?
(C) a-1, b-2, c-3 (A) Commensalism
Gene therapy focuses on treating or curing hereditary (B) Mutualism
disorders by correcting faulty genes. Transgenic animals, (C) Parasitism
such as cows or sheep, can be engineered to produce (D) Competition
therapeutic proteins in milk. Bt crops, containing

Ans
Bacillus thuringiensis genes, resist insect pests. Hence, (A) Commensalism
a-1, b-2, c-3 accurately matches these biotechnology Commensalism occurs when one organism benefits
applications. from the relationship, while the other remains neither
32. Arrange these biotechnology steps in correct sequence harmed nor helped. Mutualism benefits both, parasitism
for creating a transgenic plant: benefits one at the expense of the other, and competition
1. Isolate desired gene often negatively impacts both species competing for
2. Insert gene into vector limited resources. Commensalism thus represents a
3. Transform host plant cells neutral-positive ecological interaction.
4. Regenerate plant 35. Which of the following is NOT a population attribute?
(A) 2 → 1 → 3 → 4 (A) Birth rate
(B) 3 → 4 → 1 → 2 (B) Age distribution
(C) 1 → 2 → 3 → 4 (C) Ecosystem trophic level
(D) 1 → 3 → 4 → 2 (D) Death rate


Ans

Ans
(C) 1 → 2 → 3 → 4 (C) Ecosystem trophic level
The process begins by isolating the target gene, cloning Population attributes include birth and death rates, sex
it into a suitable vector, and transferring it into the plant ratios, and age structures. These parameters specifically
cells (often via Agrobacterium). Lastly, regenerating relate to a single species living in a defined region. In

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 PRACTICE PAPER 18

contrast, an “ecosystem trophic level” describes a (A) 1 and 3

broader ecological concept dealing with energy flow and (B) 2 and 4
feeding positions, not an attribute of one population. (C) 1, 2, and 4
(D) 1, 3, and 4
36. Assertion (A) : Predation regulates prey population
sizes.

Ans
Reason (R) : Predators remove only the weakest (A) 1 and 3
individuals, leaving the stronger to thrive. Ecological pyramids illustrate the relationships among
(A) Both true, Reason correct explanation trophic levels by representing biomass, energy, or
(B) Both true, Reason not correct explanation numbers. They are often upright, although some can
(C) Assertion true, Reason false be inverted in special cases. Multiple apex predators
(D) Both false may exist, but it is not mandatory. Hence, statements 1


Ans and 3 precisely define the general nature of ecological
pyramids.
(B) Both true, but Reason is not the correct explanation.
Predators indeed limit prey abundance by consuming 39. In an ecosystem’s energy flow, which level typically has
individuals. The statement that they remove “only the the highest energy content?
weakest” is an oversimplification; while weaker or more (A) Primary consumers
vulnerable individuals are often targeted, predator-prey (B) Secondary consumers
dynamics are more complex. Thus, while predation does (C) Tertiary consumers
regulate populations, focusing solely on removing the (D) Producers
weakest is not a complete explanation.

Ans
37. Match each term with its general meaning: (D) Producers
Producers (plants, algae) trap solar energy, initiating
Column I Column II
the food chain. Each subsequent trophic transfer loses
a. Biomass 1. Total living matter in an area energy mainly as heat, resulting in diminishing energy
b. Decomposer 2. Breaks down dead organic availability at higher trophic levels. Therefore, producers
matter typically contain the greatest energy content, forming
c. Food chain 3. Transfer of energy from one the broad base of the energy pyramid in ecosystems.
trophic level to another
40. Which region is characterized by exceptionally high
Options: levels of biodiversity and endemism but faces severe
(A) a-1, b-2, c-3 threat?
(B) a-2, b-3, c-1 (A) Tundra zone
(C) a-3, b-1, c-2 (B) Biodiversity hotspot
(D) a-1, b-3, c-2 (C) Coral atoll


Ans (D) Mangrove swamp
(A) a-1, b-2, c-3

Ans
Biomass is the total mass of organisms in a defined (B) Biodiversity hotspot
area or volume. Decomposers, like bacteria and fungi, Biodiversity hotspots are regions with extraordinary
break down dead and decaying organic matter, recycling species richness and high numbers of endemic
nutrients. A food chain depicts the flow of energy from organisms but are under considerable threat of habitat
producers to higher trophic levels. Thus, a-1, b-2, c-3 is loss and other anthropogenic factors. Tundras, coral
correct. atolls, and mangroves are unique ecological zones,
38. Which statements accurately describe ecological yet the term “hotspot” specifically denotes areas both
pyramids? immensely diverse and critically endangered.
1. Show trophic levels

Direction :Carefully read the case study provided and then
2. Always inverted thoroughly answer the subsequent five questions.
3. Depict biomass or energy Sneha volunteered at a healthcare camp organized in a
4. Must have multiple apex predators remote village grappling with a sudden increase in dengue

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page 182 CUET UG Biology

cases. Working alongside a medical team, she observed (C) Blurred vision
inadequate sanitation and abundant mosquito breeding (D) Ear discharge
grounds. People lacked awareness about draining

Ans
stagnant water and disposing of containers that could
serve as larval habitats. Sneha collaborated with local (B) Joint pain and high fever
authorities, leading an initiative for mass clean-up drives, Dengue commonly presents with high fever, severe
insecticide sprays, and distribution of mosquito nets. headache, joint and muscle pain, and sometimes
She also arranged educational sessions on early dengue a characteristic rash. Early identification of these
symptoms, emphasizing hydration and immediate symptoms, alongside immediate medical consultation,
medical consultation. Over weeks, reported cases dropped helps prevent complications like hemorrhagic fever or
significantly, highlighting how vector control and public shock. Mild cough, blurred vision, or ear discharge are
awareness directly cut disease transmission rates. The not typical initial features of dengue infection.
village’s experience showcased the power of preventive 44. Why did reported dengue cases drop significantly in the
measures in curbing vector-borne diseases. village?
41. Which primary factor contributed to the spread of (A) Complete elimination of all viruses
dengue in this village? (B) Coordinated vector control and public education
(A) Contaminated food sources (C) Mass closure of water sources
(B) Overuse of antibiotics (D) Ban on any healthcare visits
(C) Improper disposal of stagnant water

Ans
(D) Lack of vaccination (B) Coordinated vector control and public education


Ans The decrease in cases stemmed from comprehensive
(C) Improper disposal of stagnant water measures: cleaning up mosquito breeding sites, spraying
Aedes mosquitoes, which transmit dengue, often breed insecticides, and educating residents on symptom
in standing water found in containers, discarded tires, or recognition and prevention. Collective involvement
trash. Without proper water disposal, these mosquitoes helped interrupt the disease’s transmission cycle.
thrive and facilitate rapid disease spread. Vaccination Eliminating water sources entirely is unrealistic, while
for dengue is limited in many regions, so controlling banning healthcare visits would worsen public health,
breeding sites remains the first line of preventive action. not improve it.

45. What is the broader lesson from this outbreak

42. Which strategy did Sneha and the local authorities
implement to reduce mosquito breeding? management?
(A) Relying solely on herbal remedies (A) Vector-borne diseases cannot be controlled
(B) Spraying insecticides and removing stagnant water (B) Preventive measures and awareness greatly reduce
(C) Stopping all local transport infection rates
(D) Enforcing strict curfews (C) Only vaccines can halt dengue spread
(D) Antibiotics are critical for dengue care


Ans


Ans
(B) Spraying insecticides and removing stagnant water
Effective vector control in dengue-endemic areas hinges (B) Preventive measures and awareness greatly reduce
on eliminating possible breeding sites and reducing adult infection rates
mosquito populations through insecticide spraying. The village’s success story underlines how early
Herbal remedies might provide supplementary relief, detection, sanitation improvements, and active
but they do not eradicate mosquitoes. Restricting community participation can significantly lower
transport or imposing curfews is unrelated to directly transmission of dengue. Targeted interventions such
halting mosquito breeding cycles. as draining stagnant water, personal protection, and
prompt treatment collectively curtailed the outbreak.
43. Which symptom of dengue would the sessions most Vaccines and antibiotics are not the primary solutions
likely emphasize for early detection? for typical dengue management.
(A) Mild cough
(B) Joint pain and high fever

Direction :Carefully read the case study provided and then
thoroughly answer the subsequent five questions.

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 PRACTICE PAPER 18

Anya is a research student studying how genetically 48. Which process likely assists in purifying the produced
modified bacteria can produce insulin. She cultivates insulin from bacterial cultures?
bacterial strains modified to contain the human insulin (A) Gel electrophoresis
gene within a plasmid vector. By providing optimal (B) Southern blotting
nutrient media and maintaining sterile conditions, (C) Chromatography
Anya encourages bacterial growth. The recombinant (D) Gram staining
bacteria express insulin, which she then isolates using

Ans
chromatographic techniques. To ensure product safety,
Anya conducts purity checks verifying that no bacterial (C) Chromatography
contaminants remain. She also compares the structure Chromatography encompasses a set of techniques
of the lab-produced insulin to its natural human (e.g., affinity, ion-exchange) for separating compounds
counterpart. The results reveal correct folding and based on chemical properties. Researchers commonly
bioactivity, matching pharmaceutical standards. This use affinity chromatography to isolate recombinant
success highlights how recombinant DNA technology can proteins like insulin. Gel electrophoresis separates
address health challenges by efficiently manufacturing nucleic acids or proteins mainly for analysis, whereas
important biomolecules, benefiting patients worldwide Southern blotting and Gram staining are diagnostic, not
with safer, mass-produced therapeutic proteins. purification, methods.

49. Why does Anya compare the lab-produced insulin

46. Which genetic component ensures bacteria can produce
human insulin? structure to natural insulin?
(A) Viral capsid proteins (A) To confirm identical functional properties
(B) Plasmid carrying the insulin gene (B) To show it lacks all amino acids
(C) Bacterial ribosomal subunits (C) To produce an unrelated antigen
(D) Restriction enzyme sites (D) To detect bacterial toxins

Ans

Ans

(B) Plasmid carrying the insulin gene (A) To confirm identical functional properties
In recombinant DNA technology, a plasmid vector Matching the recombinant insulin’s structure and
harboring the human insulin gene is introduced activity to naturally occurring human insulin ensures
into the bacterial host. The host’s protein synthesis it functions properly and safely for therapeutic use. If
machinery then translates this gene into insulin. Viral structural or folding discrepancies existed, the protein
capsid proteins and restriction enzyme sites are tools in might not bind insulin receptors effectively. Verifying its
cloning, but the actual production depends on a plasmid similarity confirms it can regulate blood glucose levels
with the insulin gene. like endogenous insulin.

50. What broader impact does this technology demonstrate?

47. What critical factor must be maintained to prevent
contamination during bacterial growth? (A) It limits medical innovation
(A) Elevated oxygen levels (B) It solely benefits bacterial research
(B) Sterile culture conditions (C) It offers scalable production of therapeutic proteins
(C) Use of antibiotic-free media only (D) It replaces all diagnostic procedures
(D) Keeping cultures exposed to open air

Ans


Ans (C) It offers scalable production of therapeutic proteins
(B) Sterile culture conditions Recombinant DNA technology allows mass production
Maintaining sterility is essential for recombinant of critical human proteins, such as insulin, in microbial
bacteria to thrive without interference from competing systems. This capability expands access to life-
microorganisms. Controlled laboratory environments saving medications, improving global healthcare. It
ensure minimal contaminants, preserving product supplements rather than replaces diagnostics or other
integrity. Antibiotic-free media isn’t always appropriate medical advances. Overall, it illustrates how genetic
because selecting for antibiotic resistance markers engineering addresses major treatment needs effectively
helps confirm plasmid retention. Exposed cultures risk and affordably.
contamination and compromise results.

*************

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page 184 CUET UG Biology

PRACTICE PAPER 19

1. Which process describes pollination occurring within Double fertilization involves one sperm fusing with the
the same flower on a plant? egg, forming the zygote, while the other sperm fuses
(A) Autogamy with the polar nuclei to form the triploid endosperm.
(B) Xenogamy This concurrent formation of embryo and nourishing
(C) Geitonogamy endosperm is unique to angiosperms, ensuring
(D) Allogamy synchronized resource allocation and proper seed


Ans development for successful germination.

(A) Autogamy 4. Which structure in the male reproductive system is the

Autogamy is the process in which pollen is transferred primary site of sperm maturation?
from the anther to the stigma of the same flower, (A) Epididymis
enabling self-fertilization. This contrasts with xenogamy, (B) Vas deferens
which involves different plants, and geitonogamy, which (C) Seminal vesicle
involves different flowers on the same plant. Allogamy (D) Prostate gland
specifically denotes cross-pollination between separate

Ans
individuals.
(A) Epididymis
2. Which part of the flower develops into the seed after The epididymis provides an environment for sperm to
fertilization? acquire motility and the ability to fertilize an ovum.
(A) Ovary After production in the seminiferous tubules, sperm
(B) Ovule travel to the epididymis, where they undergo crucial
(C) Stigma physiological changes. This process prepares the sperm
(D) Style for their subsequent journey through the vas deferens


Ans and beyond.

(B) Ovule 5. Which of the following does NOT occur during the
After successful fertilization, the ovule matures into the proliferative phase of the menstrual cycle?
seed containing the embryonic plant and stored food. (A) Repair of the endometrium
The ovary, meanwhile, grows into the fruit that encloses (B) Rising estrogen levels
the seed. The stigma and style facilitate pollen reception (C) Follicular development in the ovary
and transfer but do not themselves develop into seeds (D) Massive shedding of the uterine lining
after fertilization.

Ans
3. Which statement best explains the significance of (D) Massive shedding of the uterine lining
double fertilization in flowering plants? During the proliferative phase, the uterine lining
(A) It produces twins regenerates under rising estrogen levels, and ovarian
(B) It forms two pollen tubes follicles mature. The shedding of the uterine lining
(C) It ensures coordinated embryo and endosperm characterizes the menstrual phase, not the proliferative
development phase. Thus, heavy endometrial disintegration occurs
(D) It leads to seed coat formation alone earlier, making option (D) the exception for this specific


Ans stage of the cycle.

(C) It ensures coordinated embryo and endosperm 6. Which statement correctly contrasts spermatogenesis
development with oogenesis in humans?
(A) Spermatogenesis forms one motile gamete per

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 PRACTICE PAPER 19

cycle, while oogenesis forms four 9. Which assisted reproductive technology is best for a
(B) Spermatogenesis begins at birth, while oogenesis woman with blocked fallopian tubes but healthy ovaries?
begins at puberty (A) Gamete intrafallopian transfer (GIFT)
(C) Spermatogenesis continues throughout life, while (B) In vitro fertilization (IVF)
oogenesis is cyclical after menarche (C) Zygote intrafallopian transfer (ZIFT)
(D) Spermatogenesis produces millions of sperm, while (D) Artificial insemination (AI)
oogenesis releases one ovum per cycle

Ans


Ans (B) In vitro fertilization (IVF)
(D) Spermatogenesis produces millions of sperm, while IVF bypasses fallopian tubes entirely by fertilizing the
oogenesis releases one ovum per cycle extracted eggs with sperm in a laboratory setting. Once
In males, spermatogenesis constantly generates vast the embryos form, they are transferred to the uterus for
numbers of sperm once puberty starts, continuing implantation. GIFT and ZIFT involve placing gametes
well into older age. By contrast, in females, oogenesis or zygotes in the fallopian tubes, whereas AI only
typically results in the release of a single mature ovum introduces sperm into the female tract.
per menstrual cycle. This difference underlines the
10. Which term defines the phenomenon where a single
distinct reproductive strategies employed by each sex.
gene influences multiple phenotypic traits?
7. What is the primary benefit of using contraceptive (A) Co-dominance
methods for birth control? (B) Pleiotropy
(A) Preventing gamete maturation (C) Epistasis
(B) Avoiding genetically modified offspring (D) Polygenic inheritance
(C) Regulating the timing of fertilization

Ans
(D) Preventing unwanted pregnancies
(B) Pleiotropy


Ans Pleiotropy occurs when one gene controls several distinct
(D) Preventing unwanted pregnancies and sometimes seemingly unrelated phenotypic effects
The main purpose of contraceptive methods is to in an organism. In contrast, co-dominance involves
provide reliable means of family planning by preventing the simultaneous expression of two alleles, epistasis
unintended pregnancies. Various strategies such as describes gene interactions affecting phenotypes,
barriers, pills, or devices accomplish this goal. Additional and polygenic inheritance arises from multiple genes
advantages include spacing births and reducing health contributing collectively to a single trait.
risks, though they do not directly influence genetic
11. How does incomplete dominance differ from co-
modifications or gamete maturation processes.
dominance in genetic inheritance?
8. Which sexually transmitted disease is caused by the (A) Incomplete dominance shows a blended phenotype;
Human Immunodeficiency Virus (HIV)? co-dominance shows separate phenotypic
(A) Syphilis expression
(B) Gonorrhea (B) Incomplete dominance shows only the dominant
(C) AIDS trait; co-dominance shows both traits recessively
(D) Genital herpes (C) Incomplete dominance and co-dominance are


Ans identical processes
(D) Incomplete dominance involves multiple alleles;
(C) AIDS co-dominance requires exactly two alleles
Acquired Immunodeficiency Syndrome (AIDS) arises
from infection by HIV, which compromises the immune

Ans
system over time. Syphilis is caused by Treponema (A) Incomplete dominance shows a blended phenotype;
pallidum, gonorrhea by Neisseria gonorrhoeae, and co-dominance shows separate phenotypic expression
genital herpes by the Herpes simplex virus. Thus, HIV In incomplete dominance, neither allele is fully
specifically leads to AIDS rather than the other listed dominant, producing an intermediate phenotype (such
conditions. as pink flowers from red and white parents). In co-
dominance, both alleles manifest distinctly, resulting

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page 186 CUET UG Biology

in separate phenotypic expressions (like red and white Hershey and Chase conducted experiments with
spots). Thus, they differ significantly in how the alleles radioactive phosphorus-labeled DNA and sulfur-
are exhibited. labeled proteins in bacteriophages, proving that DNA
enters bacterial cells and directs viral replication.
12. Which combination of statements is correct regarding Watson and Crick elucidated DNA’s structure, Avery
Mendelian inheritance patterns? and colleagues identified DNA as the transforming
1. The law of dominance states that one factor may principle, and Meselson and Stahl investigated DNA
mask the expression of another replication mechanisms.
2. The law of segregation refers to the separation of
alleles during gamete formation 15. Assertion (A) : In eukaryotes, mRNA is monocistronic.
3. The law of independent assortment applies to Reason (R) : Eukaryotic genes commonly contain
linked genes introns and exons.
4. Mendel performed his experiments on garden peas (A) Both (A) and (R) are true, and (R) is the correct
(A) 1 and 2 explanation of (A)
(B) 1, 2, and 3 (B) Both (A) and (R) are true, but (R) is not the correct
(C) 1, 2, and 4 explanation of (A)
(D) 2, 3, and 4 (C) (A) is true, but (R) is false


Ans (D) (A) is false, but (R) is true

(C) 1, 2, and 4

Ans

Mendel used garden peas (Pisum sativum) to propose (B) Both (A) and (R) are true, but (R) is not the correct
his laws, making statement 4 correct. Statements explanation of (A)
1 and 2 accurately describe the laws of dominance Eukaryotic mRNAs generally code for a single
and segregation. However, the law of independent polypeptide chain (monocistronic), whereas
assortment holds true primarily for unlinked genes, so prokaryotic mRNAs can be polycistronic. This property
statement 3 is incorrect regarding linked traits. is not directly attributed to the presence of introns and
exons, which primarily affect transcript processing, but
13. What role does the enzyme DNA ligase play in DNA do not themselves mandate mono- or polycistronic
replication? arrangement in the final mRNA product.
(A) It breaks hydrogen bonds between bases
(B) It joins Okazaki fragments on the lagging strand 16. Arrange the following events in the correct chronological
(C) It synthesizes new DNA strands sequence according to Darwin’s theory of evolution by
(D) It unwinds the double helix natural selection:


Ans 1. Variation occurs in populations
2. Individuals with favorable traits survive
(B) It joins Okazaki fragments on the lagging strand 3. Overproduction of offspring takes place
During replication, short stretches of DNA (Okazaki 4. Traits are passed to subsequent generations
fragments) are formed on the lagging strand. DNA (A) 3 → 1 → 2 → 4
ligase then seals these fragments into a continuous (B) 1 → 2 → 3 → 4
strand by forming phosphodiester bonds. It does not (C) 3 → 1 → 4 → 2
perform strand unwinding (helicase), hydrogen bond (D) 1 → 3 → 2 → 4
disruption, or polymerization (DNA polymerase). Thus,
its key function is strand joining.

Ans
(A) 3 → 1 → 2 → 4
14. Which scientists demonstrated that DNA is the genetic Darwin’s concept starts with overproduction, where
material using bacteriophages? more offspring are produced than can survive. Variation
(A) Hershey and Chase then emerges among individuals, enabling some to
(B) Watson and Crick survive better than others. Those with advantageous
(C) Avery, MacLeod, and McCarty traits outcompete others, ensuring survival and
(D) Meselson and Stahl reproduction. Finally, these traits are inherited, shaping


Ans future generations through natural selection.
(A) Hershey and Chase

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 PRACTICE PAPER 19

17. Which of the following is NOT a fossil-based evidence passive immunity does
for evolution? (B) Active immunity uses pre-formed antibodies;
(A) Transitional forms passive immunity requires direct infection
(B) Homologous structures in fossils (C) Active immunity is long-lasting; passive immunity
(C) Molecular clocks provides temporary protection
(D) Imprints in sedimentary rock (D) Active immunity occurs only through vaccination;


Ans passive immunity arises from natural infections

(C) Molecular clocks

Ans

Fossil evidence centers on physical remains or imprints (C) Active immunity is long-lasting; passive immunity
in geological formations, including transitional forms provides temporary protection
and morphological structures like homologous traits. Active immunity emerges when an individual’s immune
Molecular clocks, however, are based on genetic system generates antibodies following exposure to
mutation rates over time and do not rely on fossilized antigens through infection or vaccination, offering
remnants, making them a different category of prolonged defense. Passive immunity involves
evolutionary evidence. receiving ready-made antibodies, such as through
maternal transfer or immunoglobulin injections, which
18. Which is NOT a factor influencing genetic drift in a provide immediate but transient protection, as no
population? immunological memory develops.
(A) Small population size
(B) Random mating in large populations 21. Which combination of statements correctly addresses
(C) Founder effect cancer biology?
(D) Bottleneck effect 1. Cancer cells undergo uncontrolled proliferation


Ans 2. Oncogenes are mutated forms of proto-oncogenes
3. All cancers are inherited
(B) Random mating in large populations 4. Tumor suppressor genes help regulate the cell cycle
Genetic drift refers to random changes in allele (A) 1, 2, and 4
frequencies, typically more pronounced in small (B) 2, 3, and 4
populations, founder events, or bottlenecks. Large (C) 1, 3, and 4
populations with random mating exhibit stable allele (D) 1, 2, and 3
frequencies governed more by natural selection or gene
flow, rather than random fluctuations, making option

Ans
(B) the least related factor. (A) 1, 2, and 4
Cancer involves unregulated cell division, driven by
19. Which organism causes malaria in humans? oncogenes that arise from mutated proto-oncogenes,
(A) Plasmodium falciparum and partially prevented by tumor suppressor genes
(B) Trypanosoma brucei regulating growth. While some predispositions are
(C) Entamoeba histolytica inherited, not all cancers result from heritable mutations,
(D) Ascaris lumbricoides making statement 3 incorrect. Therefore, statements 1,


Ans 2, and 4 are accurate.
(A) Plasmodium falciparum 22. Match each microbe with its application in human
Malaria is primarily caused by Plasmodium species— welfare:
particularly Plasmodium falciparum, which triggers
the most serious and severe cases. Trypanosoma brucei Column I Column II
causes African sleeping sickness, Entamoeba histolytica A. Saccharomyces 1. Antibiotic
leads to amoebic dysentery, and Ascaris lumbricoides cerevisiae production
causes ascariasis. Thus, only Plasmodium falciparum is B. Penicillium 2. Bread fermentation
responsible for malaria in human hosts. notatum
20. How does active immunity differ from passive C. Methanobacterium 3. Biogas generation
immunity? D. Rhizobium 4. Nitrogen fixation
(A) Active immunity does not involve antibodies;

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Options: 25. Which term describes joining DNA from two different
(A) A-2, B-1, C-3, D-4 sources, producing a new genetic combination?
(B) A-1, B-2, C-4, D-3 (A) Hybridization
(C) A-2, B-3, C-4, D-1 (B) Recombinant DNA
(D) A-4, B-1, C-2, D-3 (C) Polymerization


Ans (D) Transformation

(A) A-2, B-1, C-3, D-4

Ans

Saccharomyces cerevisiae is yeast employed in baking (B) Recombinant DNA
and fermentation, Penicillium notatum produces the Recombinant DNA technology involves cutting DNA
antibiotic penicillin, Methanobacterium helps generate from different organisms with restriction enzymes
biogas (methane), and Rhizobium fixes atmospheric and ligating them to create novel genetic constructs.
nitrogen in legumes. Each microbe contributes uniquely Hybridization typically refers to crossing different
to human welfare through its specific biological activity species or varieties, polymerization describes the
or metabolic product. These roles collectively impact formation of polymers, and transformation involves
industries such as food and medicine. introducing foreign DNA into a cell without necessarily
creating hybrid molecules.
23. Which microbe is crucial for the commercial production
of citric acid? 26. Which statements regarding restriction enzymes are
(A) Aspergillus niger correct?
(B) Lactobacillus acidophilus 1. They recognize specific palindromic DNA
(C) Streptococcus thermophilus sequences
(D) Acetobacter aceti 2. They cut RNA for protein synthesis


Ans 3. They generate sticky or blunt ends
4. They are used in recombinant DNA procedures
(A) Aspergillus niger (A) 1, 2, and 4
Aspergillus niger, a filamentous fungus, is extensively (B) 1, 3, and 4
used for citric acid production through fermentation (C) 2, 3, and 4
processes. Lactobacillus acidophilus and Streptococcus (D) 1 and 3 only
thermophilus are primarily involved in dairy
fermentations, while Acetobacter aceti is linked

Ans
to vinegar production. Thus, Aspergillus niger is (B) 1, 3, and 4
specifically critical for large-scale citric acid synthesis. Restriction enzymes bind to palindromic DNA sites
and cleave the DNA, producing sticky or blunt ends
24. Why are biofertilizers like Rhizobium and Azotobacter vital for molecular cloning. They do not cut RNA as
environmentally beneficial compared to chemical part of translation, so statement 2 is incorrect. Their key
fertilizers? function lies in recombinant DNA technology, enabling
(A) They enhance soil erosion gene insertion and manipulation.
(B) They fix atmospheric nitrogen naturally
(C) They eliminate the need for crop rotation 27. Match each step in recombinant DNA technology with
(D) They remain inactive in the soil its correct description:


Ans Column I Column II
(B) They fix atmospheric nitrogen naturally A. Restriction 1. Sealing DNA fragments
Biofertilizers rely on microbial activity to convert digestion
atmospheric nitrogen into forms usable by plants, B. Ligation 2. Cutting DNA at specific
reducing dependency on synthetic chemicals. This sites
sustainable approach helps maintain soil fertility, lowers C. Transformation 3. Introducing DNA into a
chemical runoff, and promotes ecological balance. host cell
Therefore, they offer an environmentally friendly
D. Screening 4. Identifying successful
alternative without increasing erosion or eliminating
recombinants
crop rotation practices.

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 PRACTICE PAPER 19

Options: providing inherent pest resistance. Since the insecticidal

(A) A-2, B-1, C-3, D-4 trait directly stems from the introduced Bt gene, the
(B) A-1, B-2, C-4, D-3 reason correctly explains the assertion.
(C) A-3, B-4, C-2, D-1
30. Match the following biotechnological products with
(D) A-4, B-3, C-1, D-2
their descriptions:


Ans
Column I Column II
(A) A-2, B-1, C-3, D-4
Restriction digestion uses restriction endonucleases to A. Gene therapy 1. Replacing defective genes
cut DNA at specific sequences, ligation merges DNA B. Stem cell 2. Generating specialized
fragments using ligase, transformation introduces technology cell types
recombinant DNA into the host cell, and screening C. Golden Rice 3. Enriched with vitamin A
identifies cells that successfully integrated the D. Biopiracy 4. Unauthorized commercial
recombinant vector. These sequential steps form the use of biological resources
cornerstone of genetic engineering protocols.
Options:
28. Which of the following is NOT an application of (A) A-1, B-2, C-3, D-4
biotechnology in agriculture? (B) A-2, B-1, C-4, D-3
(A) Development of Bt crops (C) A-4, B-3, C-2, D-1
(B) Creating pest-resistant varieties (D) A-3, B-4, C-1, D-2
(C) Generating transgenic animals for organ

Ans
transplantation
(A) A-1, B-2, C-3, D-4
(D) Engineering herbicide-tolerant plants
Gene therapy targets genetic diseases by substituting


Ans flawed genes with functional ones, stem cell technology
(C) Generating transgenic animals for organ aims to differentiate cells for medical treatments, Golden
transplantation Rice is genetically engineered to contain higher levels
Agricultural biotechnology focuses on improving crop of β-carotene (vitamin A precursor), and biopiracy
traits, like pest resistance and herbicide tolerance, or involves exploiting biological materials without proper
producing Bt crops with built-in insecticidal proteins. authorization.
Transgenic animals for organ transplantation relate more
31. Which term describes the mutually beneficial
to biomedical research than agricultural enhancement,
relationship between two species?
thus making option (C) outside the domain of direct
(A) Predation
agricultural applications.
(B) Mutualism
29. Assertion (A) : Bt cotton plants produce an insecticidal (C) Parasitism
protein toxic to bollworms. (D) Commensalism
Reason (R) : The Bt gene is derived from the bacterium

Ans
Bacillus thuringiensis.
(B) Mutualism
(A) Both (A) and (R) are true, and (R) is the correct
Mutualism is a symbiotic interaction where both species
explanation of (A)
gain direct benefits, like pollinators obtaining nectar
(B) Both (A)and (R) are true, but (R) is not the correct
while helping plants reproduce. Predation involves one
explanation of (A)
organism consuming another, parasitism benefits one
(C) (A) is true, but (R) is false
partner at the expense of the other, and commensalism
(D) (A) is false, but (R) is true
helps one species without significantly affecting the


Ans other.
(A) Both (A) and (R) are true, and (R) is the correct
32. Which statements about population attributes are
explanation of (A)
accurate?
Bt cotton expresses Cry proteins coded by genes
1. Birth rate affects population growth
extracted from Bacillus thuringiensis. These proteins are
2. Death rate cannot alter population size
very highly toxic to specific insects like bollworms, thus
3. Age distribution profiles reveal reproductive status

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4. Mutualism is the only population interaction (C) A significant portion is lost as heat or used in
(A) 1 and 3 metabolism
(B) 1, 2, and 3 Organisms expend energy for their life processes, such
(C) 2 and 4 as movement, growth, and maintenance, releasing
(D) 1, 3, and 4 much of it as heat. Only a fraction remains available for


Ans consumption by the next trophic level. Consequently,
about 10% of the energy is passed on, while the rest
(A) 1 and 3 dissipates or is utilized metabolically.
Population size changes with both birth and death rates,
making statement 2 incorrect, and multiple interactions 35. Which of the following best describes the standing crop
beyond mutualism exist, invalidating statement 4. in an ecosystem?
Age distribution data indeed provide insights into the (A) Total energy at the producer level
reproductive condition of the population, so statements (B) Dry weight of living organisms at a given time
1 and 3 accurately capture key population attributes. (C) Number of decomposers
(D) Combined mass of all non-living components
33. Match each population interaction with its general
outcome:

Ans
(B) Dry weight of living organisms at a given time
Column I Column II
Standing crop indicates the biomass of organisms,
A. Competition 1. Both species harmed usually producers, in a specific area at a specific
B. Predation 2. One benefits, one killed moment, often measured by their dry weight. It does
C. Commensalism 3. One benefits, other neutral not represent total energy content, decomposer count,
D. Parasitism 4. One benefits, other or non-living mass. This measure helps assess the
harmed but not killed ecosystem’s immediate overall productivity status.
immediately
36. Arrange the steps of decomposition in the correct
Options: sequence:
(A) A-1, B-2, C-3, D-4 1. Fragmentation
(B) A-2, B-1, C-4, D-3 2. Humification
(C) A-4, B-3, C-2, D-1 3. Catabolism
(D) A-3, B-1, C-4, D-2 4. Mineralization


Ans (A) 1 → 3 → 2 → 4
(B) 3 → 1 → 4 → 2
(A) A-1, B-2, C-3, D-4
(C) 1 → 2 → 3 → 4
Competition adversely affects both species, predation
(D) 2 → 1 → 4 → 3
eliminates one prey for the predator’s benefit,
commensalism allows one species to gain without

Ans
harming the other, and parasitism benefits the parasite (A) 1 → 3 → 2 → 4
while harming, but not immediately killing, the host. Decomposition typically begins with fragmentation of
These classifications capture the ecological impacts of detritus into smaller particles, followed by catabolism
each interaction. through microbial enzymes. Subsequently, humification
produces dark-colored humus, and mineralization
34. In an ecosystem’s energy flow, why is only about 10% of
releases inorganic nutrients from the decomposed
energy transferred to the next trophic level?
matter. Hence, the sequence is fragmentation,
(A) Energy is never lost
catabolism, humification, and finally mineralization.
(B) Most energy is stored as ATP
These processes collectively recycle organic matter in
(C) A significant portion is lost as heat or used in
ecosystems.
metabolism
(D) Primary producers capture all solar energy 37. Which term refers to species at risk of extinction if no
effectively protective measures are taken?


Ans (A) Endemic
(B) Vulnerable

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 PRACTICE PAPER 19

(C) Exotic In situ conservation safeguards species where they

(D) Domesticated naturally occur, ex situ approaches preserve them


Ans outside their habitats (e.g., seed banks), sacred groves
are community-protected forest patches, and wildlife
(B) Vulnerable sanctuaries provide habitats for wild animal populations
A vulnerable species is one facing a high risk of extinction under governmental or community oversight. This
in the medium-term future if threats persist. Endemic structure helps maintain ecological balance and protect
species are those restricted to certain regions, exotic genetic diversity.
species are introduced non-natives, and domesticated
species are tamed or cultivated by humans. Hence, 40. Which strategy best addresses the threat of biodiversity
vulnerability signals impending survival challenges. loss due to habitat destruction?
(A) Encouraging ornamental plant breeding only
38. Which statements about biodiversity hotspots are true? (B) Expanding protected areas and reserves
1. They possess high levels of endemic species (C) Introducing more invasive species
2. They have experienced minimal habitat loss (D) Eliminating wildlife corridors to restrict movement
3. They are priority regions for conservation
4. They contain mainly domesticated species

Ans
(A) 1 and 2 (B) Expanding protected areas and reserves
(B) 1 and 3 Establishing or enlarging reserves gives native species
(C) 2 and 4 room to thrive and recover from anthropogenic
(D) 1, 3, and 4 pressures, including deforestation or fragmentation.


Ans Ornamental breeding doesn’t directly address habitat
loss, invasive species often severely worsen biodiversity
(B) 1 and 3 threats, and removing wildlife corridors drastically
Biodiversity hotspots boast exceptional numbers of restricts gene flow, further harming vulnerable
endemic species and have suffered substantial habitat populations.
loss, making them urgent priorities for conservation.
They do not primarily feature domesticated species,

Direction :Carefully read the case study provided and then
and statement 2 is incorrect since these regions face thoroughly answer the subsequent five questions.
significant anthropogenic pressures that threaten their In a rural region, farmers cultivate genetically modified
unique flora and fauna. Bt cotton to combat bollworm infestation. However, over
several planting seasons, they notice declining soil fertility
39. Match each conservation approach with its main feature: and suspect inadequate crop rotation. Additionally,
Column I Column II nearby communities report an increase in pesticide-
A. In situ 1. Protection of species in resistant insects, possibly due to overuse of chemical
conservation their natural habitat sprays alongside Bt crops. Agricultural experts suggest
integrating organic manure, rotating with leguminous
B. Ex situ 2. Conservation in botanical
plants, and minimizing pesticide application. Local
conservation gardens or seed banks
scientists also propose introducing biological control
C. Sacred groves 3. Traditionally protected agents to preserve beneficial organisms in the area.
forest patches Despite these recommendations, farmers express concern
D. Wildlife 4. Protected area for wild about potential impacts on crop yield and profits. They
sanctuary animals worry that adopting more sustainable practices might
Options: require extra labor or initial investments. Still, they
(A) A-2, B-1, C-4, D-3 recognize the urgent need for a balanced approach that
(B) A-1, B-2, C-3, D-4 maintains productivity while safeguarding long-term
(C) A-3, B-4, C-1, D-2 soil health. Public awareness campaigns aim to promote
(D) A-4, B-3, C-2, D-1 responsible farming techniques.


Ans 41. Which primary concern do farmers have regarding
(B) A-1, B-2, C-3, D-4 adopting sustainable practices?
(A) That bollworms will become less resistant

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page 192 CUET UG Biology

(B) That the harvest season will shorten drastically (C) They already have pesticide-free farmland
(C) That they might face reduced immediate profits (D) They have replaced Bt cotton with traditional
(D) That Bt crops no longer produce toxins varieties


Ans

Ans
(C) That they might face reduced immediate profits (B) They are concerned about immediate yield loss
Farmers worry about the financial viability of shifting to From the case, farmers worry that fewer pesticides
more sustainable methods, including possible reduced could lead to uncontrolled pest outbreaks, thereby
yields or increased costs. The case study indicates their jeopardizing their harvests. Although sustainable
fear that adopting organic manure, crop rotation, and techniques focus on ecological balance and long-term
reduced pesticide usage might require extra labor or benefits, the fear of short-term economic damage
capital, potentially lowering immediate profitability. discourages some producers from curbing pesticide
application. This concern remains a critical barrier to
42. Why might pesticide-resistant insects be increasing in adopting ecologically safer practices.
nearby communities?
(A) Exclusive reliance on organic manure 45. Which measure could help preserve beneficial
(B) Overapplication of chemical pesticides organisms while maintaining crop health?
(C) Complete absence of legume crops (A) Using only synthetic fertilizers
(D) Use of disease-resistant crop varieties (B) Applying narrow-spectrum biological control


Ans agents
(C) Planting the same crop repeatedly
(B) Overapplication of chemical pesticides (D) Doubling chemical pesticide doses
When farmers repeatedly apply the same or excessive
pesticides, insect populations adapt genetically quite

Ans
rapidly, leading to strains with heightened resistance. (B) Applying narrow-spectrum biological control agents
The case mentions chemical sprays used alongside Biological controls like predator insects or pathogens
Bt crops, suggesting that indiscriminate pesticide target specific pests, sparing beneficial species. Narrow-
use accelerates the emergence of resistant pests in the spectrum approaches minimize collateral damage to
surrounding communities. non-target organisms. The case suggests introducing
such methods to maintain ecological balance, unlike
43. What solution do agricultural experts recommend to heavy chemical applications that harm pollinators, soil
improve soil fertility? fauna, and other beneficial life forms.
(A) Rely solely on chemical fertilizers
(B) Inject synthetic hormones into the soil

Direction :Carefully read the case study provided and then
(C) Rotate with leguminous plants and apply organic thoroughly answer the subsequent five questions.
manure A research team investigates a coastal wetland that is
(D) Eliminate all crops except Bt cotton rapidly shrinking due to urban expansion. The wetland


Ans hosts migratory birds, several fish species, and rare
mangroves adapted to brackish waters. The expansion
(C) Rotate with leguminous plants and apply organic project, aimed at building residential complexes, threatens
manure to clear large tracts of marshland. Environmentalists
Experts advocate restoring soil health through legume- warn that destroying this fragile ecosystem could
based crop rotation, which naturally fixes nitrogen and disrupt nutrient recycling, fish spawning grounds, and
enriches soil structure. Organic manure offers additional bird nesting sites. Local communities depend on these
nutrients and fosters beneficial microorganisms. This wetlands for fishing, flood protection, and eco-tourism
combined approach addresses declining fertility better income. Although a compensation plan for displaced
than depending exclusively on chemicals or growing a fishermen is proposed, critics argue it fails to address long-
single genetically modified crop. term ecological impacts. The government is considering
44. Why are some farmers hesitant to reduce pesticide designating a portion of the wetland as a protected
usage? area, but developers claim that regulations will impede
(A) They believe pests are beneficial for soil structure economic growth. Balancing conservation efforts with
(B) They are concerned about immediate yield loss ongoing development priorities remains a contentious

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 PRACTICE PAPER 19

challenge for stakeholders. fish habitats. These services highlight the marshland’s
essential role, contradicting any idea that wetlands have
46. Which aspect of the wetland primarily benefits local no value or simply raise property prices.
fishing communities?
(A) Abundance of freshwater pearls 49. What is a key criticism of the compensation plan for
(B) Presence of nutrient-rich, fish-spawning areas displaced fishermen?
(C) Unlimited aquifer recharge for farming (A) It covers entire long-term habitat restoration
(D) Year-round irrigation channels (B) It focuses too much on foreign investors


Ans (C) It ignores broader ecological impacts beyond short-
term losses
(B) Presence of nutrient-rich, fish-spawning areas (D) It guarantees fishermen permanent farmland
The wetland ecosystem provides vital breeding and ownership
feeding grounds that sustain fish populations. This
supports commercial and subsistence fishing for local

Ans
communities. The case explicitly states that fish species (C) It ignores broader ecological impacts beyond short-
use these wetlands for spawning, making it integral term losses
to the livelihoods of fishermen who rely on abundant Critics argue that direct short-term monetary
catches. compensation fails to address the quite significant
environmental consequences of wetland destruction.
47. How could mangroves be impacted by urban expansion? While fishermen might temporarily benefit financially,
(A) They will receive greater public funding the permanent loss of ecological functions—such
(B) They might thrive in newly paved areas as biodiversity support and coastal defense—poses
(C) They could be destroyed, leading to loss of coastal unaddressed risks for both local livelihoods and regional
protection sustainability.
(D) They will automatically adapt to concrete
ecosystems 50. Which compromise solution is the government


Ans exploring?
(A) Building a dam to flood the entire wetland
(C) They could be destroyed, leading to loss of coastal (B) Moving the wetland species to zoos
protection (C) Creating a protected zone within the wetland
Mangroves buffer against coastal erosion and storm (D) Offering no legal protection for the marshland
surges by stabilizing shorelines. Urban development
often removes these protective trees, jeopardizing flood

Ans
control and habitat integrity. The case highlights that (C) Creating a protected zone within the wetland
clearing marshland includes rare mangroves, suggesting The government considers designating part of the
that such destruction undermines a crucial defense wetland as a protected area, preserving its crucial
against natural calamities along the coast. ecological functions while still allowing some
development. This measure attempts to balance urban
48. Why do environmentalists oppose the rapid marshland expansion needs with conservation, highlighting the
clearance? tension between economic growth and safeguarding
(A) They prefer urban sprawl for tourism habitats. The case explicitly mentions this proposal.
(B) They claim wetlands have no practical value
(C) Wetlands provide ecosystem services like nutrient

*************
cycling and flood control
(D) Marshlands increase property costs


Ans
(C) Wetlands provide ecosystem services like nutrient
cycling and flood control
Environmentalists emphasize wetlands’ functions—
such as filtering pollutants, buffering floods, and
cycling nutrients. The case specifically cites concerns
over disrupted nutrient recycling and diminished

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page 194 CUET UG Biology

PRACTICE PAPER 20

1. Which structure in a flower is responsible for receiving tube facilitates the transport of sperm cells to the ovule
pollen during pollination? before seed formation.
(A) Style
4. Where does fertilization most commonly occur in the
(B) Stigma
(C) Ovule human female reproductive tract?
(D) Filament (A) Vagina
(B) Uterus


Ans (C) Fallopian tube
(B) Stigma (D) Cervix
The stigma is the receptive tip of the pistil where pollen

Ans
grains land and germinate. The style connects the stigma
to the ovary, the ovule later develops into the seed, and (C) Fallopian tube
the filament is part of the stamen that holds the anther. The usual site for fertilization is the ampullary region
Thus, stigmatic surfaces facilitate pollination. of the fallopian tube, where the ovum and sperm meet.
The embryo then travels to the uterus for implantation.
2. What is apomixis in flowering plants? Fertilization rarely takes place in the uterus or cervix,
(A) Formation of seeds without fertilization and the vagina primarily receives sperm but does not
(B) Pollination by water facilitate fertilization.
(C) Artificial hybridization for improved yield
5. Which statement differentiates oogenesis from
(D) Growth of seedless fruits through hormones
spermatogenesis?


Ans (A) Oogenesis begins at puberty, spermatogenesis at
(A) Formation of seeds without fertilization birth
Apomixis involves asexual seed formation, enabling (B) Oogenesis forms four ovums from each primary
seed production without the fusion of male and female oocyte, spermatogenesis forms one sperm
gametes. This phenomenon helps preserve parental (C) Oogenesis is mostly complete by birth,
traits. In contrast, pollination by water (hydrophily) spermatogenesis starts at puberty
is just a transfer mechanism, hormone-induced (D) Oogenesis produces millions of gametes daily,
parthenocarpy yields seedless fruits, and hybridization spermatogenesis does not
involves cross-fertilization processes for genetic

Ans
variation.
(C) Oogenesis is mostly complete by birth,
3. Which plant structure commonly protects seeds until spermatogenesis starts at puberty
they are ready for dispersal? Female embryos already form primary oocytes before
(A) Sepals birth, which remain arrested until puberty. By contrast,
(B) Fruit spermatogenesis commences at puberty in males and
(C) Petals continues lifelong. The quantity of sperms produced is
(D) Pollen tube vast, whereas typically only one mature ovum forms per


Ans cycle from a primary oocyte in females.

(B) Fruit 6. Which of the following is NOT part of the female

After fertilization, the ovary in angiosperms typically external genitalia (vulva)?
develops into the fruit, which encloses and safeguards (A) Labia majora
the seeds until dispersal. Sepals and petals are floral (B) Labia minora
parts that protect or attract pollinators, while the pollen (C) Clitoris

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 PRACTICE PAPER 20

(D) Cervix ICSI involves injecting a single healthy sperm directly

Ans into an ovum, making it highly effective when sperm
count or motility is severely compromised. GIFT places
(D) Cervix gametes into the fallopian tube, IUI deposits sperm into
The vulva includes structures such as the labia majora, the uterus, and tubal ligation is a sterilization procedure
labia minora, clitoris, and the vestibule. The cervix is the unrelated to overcoming male infertility.
lower narrow portion of the uterus that projects into the
vagina, making it part of the internal reproductive tract, 10. Which cross led Gregor Mendel to propose the law of
not the external genitalia. segregation?
(A) Monohybrid cross
7. Which contraceptive method involves a small T-shaped (B) Dihybrid cross
device placed in the uterus? (C) Reciprocal cross
(A) Combined oral pill (D) Test cross with two traits
(B) Copper IUD
(C) Condom

Ans
(D) Diaphragm (A) Monohybrid cross


Ans Mendel’s monohybrid crosses, involving a single pair
of contrasting traits, illustrated that alleles separate
(B) Copper IUD (segregate) during gamete formation. His dihybrid
An intrauterine device (IUD), often containing copper, crosses were instrumental for the law of independent
is a T-shaped structure inserted into the uterine cavity assortment, while reciprocal crosses helped confirm
to prevent pregnancy. Oral pills work hormonally, that trait inheritance was not influenced by the parent’s
condoms act as barriers over the penis, and diaphragms gender.
fit over the cervix. The copper IUD ensures long-term
contraception without daily dosing. 11. What is codominance?
(A) One allele completely masks another
8. Why might the use of condoms be particularly (B) Both alleles express their full effect in the phenotype
recommended to couples? (C) A third allele suppresses the other two
(A) They eliminate the need for intercourse (D) A blend occurs between two allele expressions
(B) They reduce the risk of sexually transmitted
diseases

Ans
(C) They permanently block sperm production (B) Both alleles express their full effect in the phenotype
(D) They alter hormonal cycles significantly In codominance, each allele in a heterozygous genotype


Ans is independently and fully manifested, as observed
in AB blood groups where both A and B antigens are
(B) They reduce the risk of sexually transmitted diseases present. Complete dominance masks the recessive
Condoms act as a barrier preventing direct contact of allele, incomplete dominance blends traits, and a
sexual fluids and thereby offering protection against suppressor allele would be an epistatic interaction, not
many STDs, including HIV. They do not permanently codominance.
halt sperm production or significantly affect hormonal
balance, and couples can still engage in intercourse 12. Which statements about multiple alleles are correct?
while using condoms. 1. They arise when a gene has more than two allele
forms
9. For a couple with severe male infertility (very low sperm 2. ABO blood group inheritance in humans is an
count), which assisted reproductive technology is most example
appropriate? 3. Only two alleles can be present in a diploid
(A) GIFT (Gamete intrafallopian transfer) organism at once
(B) Intrauterine insemination (IUI) 4. Each allele codes for a separate phenotype unrelated
(C) Intracytoplasmic sperm injection (ICSI) to the gene in question
(D) Tubal ligation (A) 1, 2, and 3


Ans (B) 2, 3, and 4
(C) Intracytoplasmic sperm injection (ICSI) (C) 1 and 4

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(D) 1 and 2 only (D) (A) is false, but (R) is true

Ans

Ans
(A) 1, 2, and 3 (C) (A) is true, but (R) is false
Multiple alleles exist at the population level, but any Prokaryotes lack a membrane-bound nucleus, so
diploid individual carries only two at a time. Human mRNA synthesis (transcription) and protein assembly
ABO blood groups illustrate this concept. However, (translation) can happen simultaneously in the
statement 4 is incorrect because each allele still pertains cytoplasm. The reason is incorrect because they do
to the same genetic locus, influencing variations of that not possess a true nucleus; in fact, that lack of nuclear
trait. compartment allows for coupled transcription and
translation.
13. Which component is NOT part of a typical eukaryotic
RNA processing mechanism? 16. Arrange these evolutionary milestones in chronological
(A) 5’ Capping order (oldest to most recent):
(B) 3’ Poly-A tail addition 1. Origin of prokaryotes
(C) Splicing out introns 2. Origin of eukaryotes
(D) Crossing over between mRNAs 3. Colonization of land by plants


Ans 4. Appearance of Homo sapiens
(A) 1 → 2 → 3 → 4
(D) Crossing over between mRNAs (B) 2 → 1 → 4 → 3
Eukaryotic pre-mRNA undergoes processing steps (C) 1 → 3 → 2 → 4
including 5’ capping, polyadenylation at the 3’ end, (D) 3 → 4 → 1 → 2
and splicing of introns. RNA molecules do not engage
in crossing over events analogous to chromosomes;

Ans
recombination is primarily a DNA-level phenomenon, (A) 1 → 2 → 3 → 4
not a standard step in mRNA maturation. Prokaryotes emerged first, followed by the evolution
of eukaryotic cells. Then plants adapted to terrestrial
14. How does DNA differ from RNA structurally? environments, setting the stage for complex ecosystems.
(A) DNA contains uracil; RNA contains thymine Much later, humans (Homo sapiens) appeared. This
(B) DNA is single-stranded; RNA is double-stranded sequence matches the widely accepted timeline in
(C) DNA uses deoxyribose sugar; RNA uses ribose evolutionary biology.
sugar
(D) DNA is made of amino acids; RNA is made of 17. Which of these does NOT provide evidence of evolution?
nucleotides (A) Comparative embryology


Ans (B) Fossil records
(C) Analogous organs
(C) DNA uses deoxyribose sugar; RNA uses ribose sugar (D) Random genetic drift
DNA has deoxyribose sugar and thymine, whereas
RNA has ribose sugar and uracil. DNA is typically

Ans
double-stranded, and RNA single-stranded, but the (D) Random genetic drift
sugar difference is a key structural hallmark. Both are Comparative embryology, fossils, and analogous organs
composed of nucleotides, not amino acids, so that final (when compared alongside homologous organs) help
statement is incorrect. trace evolutionary relationships. Random genetic drift
is a population-level mechanism of allele frequency
15. Assertion (A) : In prokaryotes, transcription and change, not a direct line of evidence like anatomical or
translation can occur simultaneously. fossil comparisons. Drift affects evolution but does not
Reason (R) : Prokaryotic cells contain a true nucleus to serve as morphological or historical proof.
separate these processes.
(A) Both (A) and (R) are true, and (R) is the correct 18. Which term describes the phenomenon of changes in
explanation of (A) allele frequency due to a small group starting a new
(B) Both (A) and (R) are true, but (R) is not the correct population?
explanation of (A) (A) Gene flow
(C) (A) is true, but (R) is false (B) Founder effect

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 PRACTICE PAPER 20

(C) Hardy-Weinberg equilibrium 21. Which statements about HIV/AIDS are correct?
(D) Genetic recombination 1. HIV directly attacks T-helper cells


Ans 2. AIDS compromises the body’s immune system
3. HIV is a bacterial pathogen
(B) Founder effect 4. Antiretroviral therapy can slow disease progression
The founder effect occurs when a few individuals from (A) 1, 2, and 4
a population colonize a new habitat, carrying only a (B) 1 and 3
fraction of the genetic variation. Gene flow involves (C) 2 and 3
movement of alleles among populations, Hardy- (D) 2, 3, and 4
Weinberg represents no-evolution conditions, and
recombination shuffles alleles during meiosis but does

Ans
not start a new population. (A) 1, 2, and 4
HIV, a retrovirus, infects and destroys T-helper cells,
19. What is vaccination? leading to immunodeficiency in AIDS. Statement 3 is
(A) Transfer of antibodies from mother to child false because HIV is viral, not bacterial. Antiretroviral
(B) Induction of immunity by administering a therapy helps manage viral load, thereby slowing
weakened pathogen disease progression. Consequently, 1, 2, and 4 accurately
(C) Passive immunization through serum injection describe HIV/AIDS.
(D) Initiation of autoimmune diseases for long-lasting
effects 22. Match each microbe with its primary commercial


Ans product or role:

(B) Induction of immunity by administering a weakened Column I Column II

pathogen A. Lactobacillus 1. Vinegar production
Vaccination involves exposing the immune system to B. Acetobacter aceti 2. Lactic acid formation
a weakened or inactivated pathogen (or its antigenic C. Penicillium 3. Antibiotic penicillin
components) to elicit protective memory responses. chrysogenum
Passive immunization involves pre-formed antibodies,
D. Spirulina 4. Protein-rich
and maternal antibody transfer is also passive.
supplement
Autoimmune disease is an abnormal self-reactivity,
unrelated to standard vaccination procedures. Options:
(A) A-1, B-2, C-4, D-3
20. How does a benign tumor differ from a malignant (B) A-2, B-1, C-3, D-4
tumor? (C) A-4, B-3, C-1, D-2
(A) Benign tumors spread aggressively; malignant ones (D) A-3, B-4, C-2, D-1
remain localized


Ans
(B) Benign tumors are always fatal; malignant ones are
harmless (B) A-2, B-1, C-3, D-4
(C) Benign tumors typically remain confined; Lactobacillus produces lactic acid (used in curd and
malignant ones invade other tissues cheese), Acetobacter aceti generates vinegar from
(D) Benign tumors cannot be detected; malignant ones ethanol, Penicillium chrysogenum produces the
are easily identified antibiotic penicillin, and Spirulina is valued as a protein-
rich supplement. These microbes each have a unique


Ans
role in industrial or nutritional applications.
(C) Benign tumors typically remain confined; malignant
ones invade other tissues 23. Why is yeast (Saccharomyces cerevisiae) widely
Benign tumors grow in a localized region and usually employed in baking?
do not metastasize. Malignant tumors, however, break (A) It synthesizes antibiotics during dough fermentation
tissue barriers, invade adjacent structures, and spread to (B) It releases carbon dioxide, causing dough to rise
distant sites (metastasis). Although a benign growth can (C) It forms lactic acid that creates sour flavor
cause problems based on size or location, it generally (D) It decomposes starch into toxins
lacks the invasive properties of malignancies.

Ans

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page 198 CUET UG Biology

(B) It releases carbon dioxide, causing dough to rise (B) 2, 3, and 4

Yeast ferments sugars, producing CO2 that inflates (C) 1, 2, and 4
dough, resulting in a spongy texture. Antibiotic (D) 1, 3, and 4
production and lactic acid fermentation are associated

Ans
with other microbes (Penicillium and Lactobacillus,
respectively). Toxic by products do not characterize (A) 1 and 3
standard baking yeast activity, making CO2 production PCR uses DNA primers (not RNA) and temperature
the key reason for its use. cycling steps (denaturation, annealing, extension).
Taq DNA polymerase tolerates high heat without
24. Which organism is commonly used as a biofertilizer to denaturing, which enables repeated cycles. Since the
fix nitrogen in root nodules of legumes? process involves multiple temperature changes, a single
(A) Saccharomyces cerevisiae constant temperature is insufficient for standard PCR
(B) Penicillium notatum protocols.
(C) Rhizobium
27. Match each tool of recombinant DNA technology with
(D) E. coli
its function:


Ans
Column I Column II
(C) Rhizobium
Rhizobium forms symbiotic associations with the roots A. Restriction 1. Joins DNA fragments
of leguminous plants, converting atmospheric nitrogen endonuclease
into ammonia. This helps increase soil fertility. Yeast B. DNA polymerase 2. Synthesizes new DNA
(Saccharomyces) is used in fermentation, Penicillium strands
notatum in antibiotic production, and E. coli is a model C. Ligase 3. Cuts DNA at specific
bacterium typically associated with genetic work or the recognition sites
gut microbiome. D. Host cell 4. Receives and replicates
the recombinant DNA
25. What is a plasmid?
(A) A cellular organelle that produces ATP Options:
(B) A small circular DNA molecule often used as a (A) A-2, B-1, C-4, D-3
cloning vector (B) A-1, B-2, C-3, D-4
(C) A protein-based hormone secreted by microbes (C) A-3, B-2, C-1, D-4
(D) A lipid droplet for energy storage in bacteria (D) A-4, B-3, C-2, D-1


Ans

Ans

(B) A small circular DNA molecule often used as a (C) A-3, B-2, C-1, D-4
cloning vector Restriction endonucleases recognize palindromic sites
Plasmids are extra-chromosomal, circular DNA and cut DNA. DNA polymerase extends the strand
molecules found in bacteria. They can replicate by adding nucleotides. Ligase seals nicks in the sugar-
independently and are frequently utilized as vectors phosphate backbone. A suitable host cell (often a
in genetic engineering. ATP production is linked to bacterium) takes up the recombinant construct and
mitochondria in eukaryotes, protein hormones are allows replication or expression of inserted genes.
unrelated to plasmids, and lipid droplets are for energy
28. Which application is NOT typically associated with
storage, not gene transfer.
transgenic plants?
26. Which statements about PCR (Polymerase Chain (A) Enhanced nutritional content
Reaction) are correct? (B) Vaccine production in edible parts
1. It amplifies specific DNA sequences exponentially (C) Fire-resistant genes for quick burning
2. It requires RNA primers (D) Pest-resistant traits (e.g., Bt toxin)
3. Taq DNA polymerase remains active at high

Ans
temperatures
(C) Fire-resistant genes for quick burning
4. It can be performed at a single constant temperature
Transgenic plants aim to improve nutrition, produce
(A) 1 and 3
vaccines (edible vaccines), or resist pests and diseases.

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 PRACTICE PAPER 20

Engineering plants to burn quickly is not a recognized 31. Which factor is primarily responsible for intraspecific
biotechnological goal; in fact, fire resistance might be competition within a population?
desirable to reduce agricultural losses, but deliberately (A) Different habitat requirements
promoting fast burning is not a standard objective. (B) Mating with a different species
(C) Limited availability of resources among individuals
29. Assertion (A) : Golden Rice is enriched with β-carotene. of the same species
Reason (R) : β-carotene is a precursor of vitamin B12 (D) Cooperative breeding with other species
in the human diet.
(A) Both (A) and (R) are true, and (R) is the correct

Ans
explanation of (A) (C) Limited availability of resources among individuals
(B) Both (A) and (R) are true, but (R) is not the correct of the same species
explanation of (A) Intraspecific competition occurs when members of the
(C) (A) is true, but (R) is false same species vie for identical resources like food, space,
(D) (A) is false, but (R) is true or mates. Interspecific competition involves different


Ans species, while cooperative breeding typically refers to
collaborative efforts within or across species that do not
(C) (A) is true, but (R) is false reflect resource contention.
Golden Rice is genetically engineered to contain
β-carotene, a precursor of vitamin A, not vitamin 32. Which statements about population growth are true?
B12. Hence, while the assertion is correct, the reason 1. Exponential growth occurs in unlimited resource
is incorrect. Vitamin A deficiency is the key problem conditions
targeted, and β-carotene helps address this nutritional 2. Logistic growth includes a carrying capacity
gap. 3. Zero population growth indicates equal birth and
death rates
30. Match each term with its biotechnology-related concept: 4. Emigration has no effect on population size
Column I Column II (A) 1, 2, and 4
A. Biopiracy 1. Unauthorized commercial (B) 2, 3, and 4
use of native resources (C) 1, 2, and 3
B. Biopatent 2. Legal right protecting
(D) 1 and 4 only
biotechnological

Ans
innovations
(C) 1, 2, and 3
C. Bioremediation 3. Using organisms to clean Exponential growth assumes abundant resources,
pollutants while logistic growth factors in carrying capacity. Zero
D. Bioreactor 4. Vessel for large-scale growth happens if births and deaths match. Emigration
microbial culture and immigration definitely alter population size, so
Options: statement 4 is incorrect. Hence, 1, 2, and 3 accurately
(A) A-2, B-1, C-3, D-4 capture crucial aspects of population growth.
(B) A-1, B-2, C-3, D-4
33. Match each term with the correct population interaction:
(C) A-3, B-1, C-4, D-2
(D) A-4, B-3, C-2, D-1 Column I Column II


Ans A. Commensalism 1. One benefits, the other
is unaffected
(B) A-1, B-2, C-3, D-4
Biopiracy concerns exploiting local biological materials B. Mutualism 2. Both benefit
without proper authorization, biopatents protect C. Parasitism 3. One benefits, the other
intellectual property rights, bioremediation employs is harmed
organisms (often microbes) to degrade contaminants, D. Amensalism 4. One is harmed, the
and bioreactors provide controlled environments for other is unaffected
mass culturing cells or microbes for product generation. Options:
(A) A-2, B-1, C-3, D-4

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(B) A-1, B-2, C-4, D-3 (C) 4 → 1 → 2 → 3

(C) A-1, B-2, C-3, D-4 (D) 1 → 3 → 2 → 4
(D) A-4, B-3, C-1, D-2

Ans


Ans (A) 1 → 2 → 3 → 4
(C) A-1, B-2, C-3, D-4 Producers capture solar energy via photosynthesis.
Commensalism aids one species without affecting the Herbivores consume these producers, followed by
other, mutualism helps both, parasitism benefits one carnivores preying on herbivores. Finally, decomposers
at the other’s expense, and amensalism harms one break down organic matter from all trophic levels. This
organism while having negligible effect on the other. sequence outlines the flow of energy from the sun to
These definitions differentiate ecological relationships producers, primary consumers, secondary consumers,
based on their impact on participants. and eventually decomposers.

34. What is primary productivity in an ecosystem? 37. Which global treaty focuses specifically on regulating
(A) Total biomass consumed by herbivores the international trade of endangered species?
(B) Rate of generation of organic material by producers (A) Convention on Biological Diversity (CBD)
(C) Energy gained by secondary consumers (B) Kyoto Protocol
(D) Standing crop of decomposers (C) Montreal Protocol


Ans (D) CITES

(B) Rate of generation of organic material by producers

Ans

Primary productivity measures the rate at which (D) CITES
autotrophs (e.g., plants, algae) synthesize organic The Convention on International Trade in Endangered
substances, typically tracked as biomass per unit area Species of Wild Fauna and Flora (CITES) protects
over time. It does not directly describe herbivore endangered organisms from overexploitation through
consumption, decomposer biomass, or secondary international trade controls. The CBD aims for overall
consumer energy intake. Instead, it focuses on producer- biodiversity conservation, the Kyoto Protocol addresses
level activity. greenhouse gases, and the Montreal Protocol targets
ozone-depleting substances.
35. Which pyramid can never be inverted in a terrestrial
ecosystem? 38. Which statements about protected areas (e.g., national
(A) Pyramid of numbers parks) are true?
(B) Pyramid of biomass 1. They restrict human activity to preserve habitats
(C) Pyramid of energy 2. They often help safeguard critical wildlife corridors
(D) Pyramid of competition 3. They are designed solely for recreational tourism


Ans 4. They can be integral to in situ conservation
(A) 1, 2, and 4
(C) Pyramid of energy (B) 2, 3, and 4
The energy pyramid is always upright because energy (C) 1 and 3
flow decreases at higher trophic levels due to losses (heat, (D) 2 and 4 only
metabolism). Pyramids of numbers or biomass can
sometimes invert (e.g., a small biomass of phytoplankton

Ans
supporting a large biomass of zooplankton), but energy (A) 1, 2, and 4
transfer constraints keep the energy pyramid upright. National parks and reserves limit destructive human
intervention, preserve wildlife corridors, and function
36. Arrange the following ecological processes in the typical as in situ conservation sites. Statement 3 is incorrect
order they occur during energy transfer: since their purpose is not solely tourism; they focus
1. Photosynthesis on conservation and may allow regulated tourism but
2. Herbivory primarily protect biodiversity and habitats.
3. Carnivory
4. Decomposition 39. Match each term with its conservation concept:
(A) 1 → 2 → 3 → 4
Column I Column II
(B) 2 → 1 → 4 → 3

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 PRACTICE PAPER 20

A. Sacred lakes 1. Community-protected Despite recommendations from agricultural officers

water bodies to cultivate drought-resistant varieties and implement
efficient drip irrigation, many farmers hesitate due to
B. Ramsar sites 2. Internationally important
initial setup costs and lack of awareness. Meanwhile,
wetlands
neighboring villages complain of dried-out wells, forcing
C. Biosphere 3. Large areas with core, residents to travel long distances for potable water.
reserve buffer, and transition zones Environmental groups propose rainwater harvesting and
D. Hotspots 4. Regions with high watershed management to replenish aquifers. However,
endemism and threat some landowners resist, fearing regulations may
levels limit their water usage. Balancing economic interests,
Options: community needs, and long-term sustainability presents
(A) A-1, B-2, C-3, D-4 an ongoing dilemma for regional authorities.
(B) A-4, B-3, C-2, D-1
41. What is the primary cause of groundwater depletion in
(C) A-2, B-1, C-4, D-3
this region?
(D) A-1, B-4, C-2, D-3
(A) Continuous rainfall saturating the aquifers


Ans (B) Overextraction through borewell drilling
(A) A-1, B-2, C-3, D-4 (C) Complete prohibition of irrigation
Sacred lakes are traditionally preserved by local (D) Scarcity of farmland needing water
communities, Ramsar sites are recognized as wetlands

Ans
of global significance, biosphere reserves encompass
(B) Overextraction through borewell drilling
core zones for minimal disturbance and buffer zones for
The case highlights intensive borewell drilling
research, while hotspots signify regions rich in endemic
alongside high water demand for irrigation, leading
species facing severe habitat threats.
to unsustainable withdrawal of groundwater. This
40. Which conservation strategy helps preserve the genetic practice depletes aquifers faster than natural recharge
diversity of rare plant species outside their natural rates. Rainfall saturation is not the issue; rather, water-
habitats? intensive agriculture, coupled with excessive borewell
(A) Converting forests into farmland use, accelerates depletion in the region.
(B) Captive breeding of wild animals
42. Why do farmers hesitate to adopt drip irrigation
(C) Ex situ conservation in seed banks or botanical
methods?
gardens
(A) Lack of initial capital and insufficient awareness
(D) Launching large-scale tourism in fragile habitats
(B) Absence of any recommendations from officials


Ans (C) Fear that water will become contaminated
(C) Ex situ conservation in seed banks or botanical (D) Belief that drip irrigation wastes more water
gardens

Ans
Ex situ methods maintain species away from their
(A) Lack of initial capital and insufficient awareness
original environment, often in gene banks, botanical
Drip irrigation demands upfront costs for equipment
gardens, or tissue cultures, safeguarding genetic
and installation, and farmers may be unaware of its
material. This approach is especially useful for critically
long-term water-saving benefits. The case study notes
endangered plants. Converting forests, focusing solely
that some hesitate due to initial setup expenses. There
on animal breeding, or mass tourism do not ensure
is no indication that they fear contamination or that
plant genetic preservation outside natural sites.
officials have withheld such suggestions.


Direction :Carefully read the case study provided and then
43. Which potential solution is suggested by environmental
thoroughly answer the subsequent five questions.
groups to replenish aquifers?
In a semi-arid region, local communities depend on
(A) Growing only water-intensive crops
underground aquifers for irrigation. Over the past decade,
(B) Rainwater harvesting and watershed management
borewell drilling has escalated, depleting groundwater
(C) Digging deeper borewells to find more water
faster than it can recharge. Farms grow water-intensive
(D) Releasing treated sewage into farming plots
crops like sugarcane, which further strains resources.

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Ans contaminate the river, adversely affecting aquatic life and

(B) Rainwater harvesting and watershed management farmland irrigation. The floodplain is seasonally crucial
The case states that environmental groups advocate for for fish breeding and waterfowl habitats. Critics demand
collecting and channeling rainwater, alongside holistic that the company install advanced wastewater treatment
watershed practices, to boost groundwater recharge. In systems and enforce strict safety protocols. While the firm
contrast, merely drilling deeper borewells or growing promises compliance with governmental norms, some
thirsty crops worsens depletion. Treated sewage reuse locals remain skeptical, citing past incidents of lenient
is not mentioned as a primary aquifer-replenishing oversight. Environmental agencies are debating whether
approach here. to grant approval contingent on regular site inspections
and stringent penalties for non-compliance. Balancing
44. What conflict arises due to the proposed regulations on economic growth with ecological integrity remains the
water usage? core challenge.
(A) Farmers favor the regulations because water is free
(B) Landowners fear limits on their access to 46. What is the main environmental concern about building
groundwater a pharmaceutical facility near a river floodplain?
(C) Environmentalists demand immediate ban on all (A) It might reduce job opportunities for locals
drilling (B) Potential pollution from industrial effluents
(D) No tension exists; everyone supports the measures (C) Reduced drug availability for healthcare
(D) Overabundance of fish in the river


Ans


Ans
(B) Landowners fear limits on their access to
groundwater (B) Potential pollution from industrial effluents
According to the case, some landowners worry that The case highlights possible contamination from
stricter water management policies might restrict untreated or poorly managed wastewater released by
their freedom to use borewells extensively. This the plant, posing threats to aquatic ecosystems and
reveals a tension between environmental sustainability farmland irrigation. Jobs and medication supply are
and individual control over resources, leading to separate issues; an increase in fish populations is not
disagreement about regulation enforcement. identified as a concern.

45. Which crops contribute most to the region’s water 47. Why is the floodplain described as “seasonally crucial”?
stress? (A) It experiences permanent drought conditions
(A) Drought-tolerant millets (B) It has no relevance to fish or bird populations
(B) Legume pulses requiring minimal irrigation (C) It is a vital breeding ground for fish and waterfowl
(C) Water-intensive varieties like sugarcane during certain periods
(D) Low-water sorghum and pearl millet (D) It is always frozen and inaccessible for human use


Ans

Ans
(C) Water-intensive varieties like sugarcane (C) It is a vital breeding ground for fish and waterfowl
Sugarcane is well-known for its heavy water demand, during certain periods
which quickly depletes limited groundwater in semi- Floodplains often serve as temporary wetlands,
arid zones. The case explicitly states that such high- especially during rainy or flood seasons, creating
water-requirement crops exacerbate local water scarcity. spawning sites for fish and nesting areas for migratory
Millets and pulses generally use less water and are more birds. The case clarifies that aquatic life and waterfowl
sustainable for water-limited environments. depend on these seasonal changes for reproduction,
emphasizing its ecological significance.


Direction :Carefully read the case study provided and then
thoroughly answer the subsequent five questions. 48. Which measure do local critics demand for ensuring
A large pharmaceutical company plans to establish a new safe industrial operations?
production facility near a river floodplain. Proponents (A) Complete prohibition on building any factories
argue that it will generate jobs and boost the local economy. (B) Use of advanced wastewater treatment systems
However, community members and ecologists warn that (C) Relocating the floodplain to another region
untreated or poorly managed industrial effluents could (D) Allowing unregulated effluent discharge to reduce

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 PRACTICE PAPER 20

costs


Ans
(B) Use of advanced wastewater treatment systems
Critics insist on properly managing effluents with high-
end treatment processes and strict safety protocols. The
scenario specifically mentions calls for advanced systems
to prevent river pollution. Neither total prohibition nor
relocating the natural floodplain is considered a feasible
solution, and unregulated discharge is precisely what
they oppose.

49. Why are some locals skeptical about the company’s

promises of compliance?
(A) They believe floodplains are invulnerable to
pollution
(B) They recall past incidents of lax enforcement
(C) They have no interest in environmental safety
(D) They think the factory will produce herbal
medicines only


Ans
(B) They recall past incidents of lax enforcement
The text states that previous lenient oversight fuels
doubts about whether the firm will actually adhere to
strict standards. Locals worry that official promises
or regulations might not be enforced consistently,
given past experiences of weak regulatory actions and
pollution events.

50. Which statement best summarizes the core challenge

mentioned in the case?
(A) Stopping economic expansion to preserve wildlife
completely
(B) Allowing total environmental degradation for
profit
(C) Balancing job creation and local development with
ecological protection
(D) Shifting pharmaceutical production entirely to
remote desert areas


Ans
(C) Balancing job creation and local development with
ecological protection
The final line highlights the tension between economic
growth and preserving the river’s ecosystem.
The challenge is finding a workable compromise:
implementing sustainable industrial activities that
provide livelihoods without jeopardizing the floodplain’s
biodiversity and environmental health.

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