ARWACHIN INDIA SCHOOL
BIOLOGY 22OCTOBER 2023
Class 12 - Biology
Time Allowed: 3 hours Maximum Marks: 70
General Instructions:
All questions are compulsory.
Section A
1. One of the most resistant biological material is: [1]
a) Lignin b) Lignocellulose
c) Sporopollenin d) Hemicellulose
2. During Hybridization process anther of the bisexual flower is removed before it dehisces is called ________. [1]
a) Thrastication b) Dissection
c) Mastication d) Emasculation
3. In human males, some recessive genes express their effect because: [1]
a) Only two sex chromosome b) Only one Y-chromosome
c) Single genome d) Only one X-chromosome
4. Linkage is the: [1]
a) Generation of non-parental gene b) Generation of parental gene combination
combination
c) Physical association of two genes present on d) Physical association of two genes present on
a different chromosome the same chromosome
5. Human genome project can leads to revolutionary new ways to: [1]
a) Study the mechanism of disease b) Diagnose, treat, and prevents thousands of
development. disorder that affect human beings.
c) Study HIV disease development. d) Developing genome project of other
animals.
6. In E.coli, the lac operon gets switched on when: [1]
a) Lactose is present and it binds to the b) Lactose is present and it binds to RNA
repressor polymerase
c) Repressor binds to operator d) RNA polymerase binds to the operator
7. Animal husbandry and plant breeding programmes are the examples of: [1]
a) Mutation b) Artificial selection
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c) Reverse evolution d) Natural selection
8. Natural selection is a process in which heritable variations enabling better survival are enabled to: [1]
a) Grow faster in a new habitat b) Reproduce and leave a greater number of
progeny
c) Grow slower in a new habitat d) Reproduce and leaves less number of
progeny
9. Colostrum is rich in: [1]
a) IgA b) IgZ
c) IgF d) IgD
10. A tumor enclosed within a capsule is termed: [1]
a) Basophils b) Malignant
c) Benign d) Metastasis
11. The microbes commonly used in kitchens are: [1]
a) Lactobacillus and Yeast b) Rhizopus and Lactobacillus
c) Penicillium and Yeast d) Microspora and E. coli
12. Which one of the following is not a nitrogen-fixing organism? [1]
a) Azotobacter b) Pseudomonas
c) Nostoc d) Anabaena
13. Rop genes in pBR322 codes for: [1]
a) Ampicillin resistance b) Antibiotic resistance
c) Tetracycline resistance d) Proteins involved in replication of plasmid
14. Molecular scissors is the name given to: [1]
a) Polymerase b) Restriction enzymes
c) Ligase d) Phosphatase
15. Which out of the following is advantage of chemical safety testing on transgenic animals? [1]
a) Obtain results in less time b) Testing is long process.
c) Testing can be performed easily. d) Testing is very cost effective.
16. Bt cotton is not: [1]
a) A GM plant b) A bacterial gene expressing system
c) Insect resistant d) Resistant to all pesticides
Section B
17. Mention two strategies evolved to prevent self pollination in flowers. [2]
18. When a red flowered. Antirrhinum plant was crossed with a white flowered Antirrhinum plant, the F offspring
1 [2]
had pink flowers. Mention (a) the genotype of F plant, and (b) the reason why it did not bear the parental red or
1
white flower colours?
19. What is meant by R cells and S cells with which Frederick Griffith carried out this experiments on Streptococcus [2]
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pneumoniae? What did he prove from these experiments?
20. Are the thorns of Bougainvillea and tendrils of cucurbita homologous or analogous? What type of evolution has [2]
brought such a similarity in them?
21. State the impact of constant mechanical agitation and pumping of air in the aeration tank on the sewage during [2]
the biological treatment.
Section C
22. Draw the diagram of a microsporangium and label its wall layers. Write briefly on the role of the endothecium. [3]
23. When a cross in made between tall plant with yellow seeds (TtYy) and tall plant with green seed (Ttyy), what [3]
proportions of phenotype in the offspring could be expected to be
i. Tall and green
ii. Dwarf and green
24. Mention the role of ribosome in peptide bond formation. How does ATP facilitate it? [3]
25. What are the various routes by which transmission of human immunodeficiency virus takes place? [3]
26. Name the two different categories of microbes naturally occurring in sewage water. Explain their role in [3]
cleaning sewage water into usable water.
27. What is Biotechnology? Describe the different types of biotechnology. [3]
28. PCR is a useful tool for early diagnosis of an infectious disease. Elaborate. [3]
Section D
29. Read the following and answer any four questions: [4]
A relevant portion of β-chain of haemoglobin of a normal human is as follows
The codon for the sixth amino acid is GAG. The sixth codon GAG mutates to GAA as a result of mutation X
and into GUG as a result of mutation Y.
i. Which of the following is incorrect statement?
a. Mutation X carries no change in shape of red blood cells.
b. Mutation Y causes change in shape of red blood cell shape.
c. Both mutations X and Y causes change in shape of red blood cell shape.
d. Both Mutation X carries no change in shape of red blood cells and Mutation Y causes change in shape of
red blood cell shape.
ii. Due to mutation Y the shape of RBCs under oxygen tension will be
a. biconcave disc like
b. elongated and curve
c. circular
d. spherical.
iii. GUG is code for
a. valine
b. proline
c. glutamic acid
d. leucine
iv. Which of the following genotype shows diseased phenotype due to mutation Y?
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a. Hbs Hbs
b. HbAHbs
c. HbA HbA
d. Both Hbs Hbs and HbAHbs
v. Study the given pedigree chart for sickle-cell anaemia and select the most appropriate option for the
genotypes.
a. Genotypes of parents - HbA Hbs, HbA HbA
Genotypes of 1st and 3rd child in F1 - HbA HbA, HbA Hbs
b. Genotypes of parents - HbA Hbs, HbA Hbs
Genotypes of 1st and 3rd child in F1 - HbA HbA, HbA Hbs
c. Genotypes of parents - HbA HbA, HbA Hbs
Genotypes of 1st and 3rd child in F1 - HbA HbA, Hbs Hbs
d. Genotypes of parents - HbA Hbs, HbA Hbs
Genotypes of 1st and 3rd child in F1 - HbA Hbs, Hbs Hbs
vi. Assertion: The substitution of amino acid in the globin protein results due to the single base substitution at
the sixth codon of the beta-globin gene from GAG to GUG
Reason: The disease is controlled by a single pair of alleles, HbA and HbS.
a. Both A and R are true and R is the correct explanation of A.
b. Both A and R are true but R is not the correct explanation of A.
c. A is true but R is false.
d. Both A and R are false.
30. Read the following and answer any four questions: [4]
The DNA, which is transferred from one organism into another by joining it with the vehicle DNA is called
passenger or foreign DNA. Generally, three types of passenger DNAs are used. These are complementary DNA
(cDNA), synthetic DNA (sDNA) and random DNA. Complementary DNA (cDNA) is synthesized on RNA
template (usually mRNA) with the help of reverse transcriptase. Synthetic DNA (sDNA) is synthesized on DNA
template or without a template. Random DNA are small fragments formed by breaking a chromosome of an
organism in the presence of restriction endonucleases.
i. Reverse transcriptase enzyme was discovered by
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a. Temin and Baltimore
b. Cohen and Boyer
c. Arber and Nathan
d. Paul Berg
ii. what would happen if DNA formed by reverse transcriptase is not treated with the alkali?
a. c DNA will not be digested
b. m RNA will not be digested
c. Hydrogen bonds will not form between base pairs
d. m RNA will not be formed.
iii. An enzyme that helps in the formation of double-stranded cDNA is
a. DNA synthetase
b. ligase
c. DNA polymerase
d. helicase
iv. DNA polymerase can be obtained from
a. retrovirus
b. Agrobacterium
c. tobacco mosaic virus
d. Thermus aquaticus
v. DNA synthesised without a template is referred to as
a. complementary DNA
b. random DNA
c. synthetic DNA
d. Z-DNA
Section E
31. What background information did Watson and Crick have made available for developing a model of DNA? [5]
What was their contribution?
32. Fill in the table with appropriate term [5]
Disease Microbe Target Organ Mode of Transmission
Meningitis Virus _ (i) _ Faecal contamination
Hepatitis _ (ii) _ _ (iii) _ Contaminated water
_ (iv) _ Bacteria Lungs _ (v) _
Ringworm Fungus _ (vi) _ Indirect contact
_ (vii) _ Virus Lungs _ (Viii) _
Dengue fever _ (ix) _ Whole body _ (x) _
33. Name the nematode that damages the roots of tobacco plants. How is a transgenic tobacco plant made resistant [5]
to nematode using biotechnology?
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