NODIA APP Sample Paper 20 Page 1
Sample Paper 20
Class XII 2024-25
Biology (044)
Time: 3 Hours Max. Marks: 70
General Instructions:
1. All questions are compulsory.
2. The question paper has five sections and 33 questions. All questions are compulsory.
3. Section—A has 16 questions of 1 mark each; Section—B has 5 questions of 2 marks each; Section—C
has 7 questions of 3 marks each: Section—D has 2 case-based questions of 4 marks each; and Section—E
has 3 questions of 5 marks each.
4. There is no overall choice. However, internal choices have been provided in some questions. A student
has to attempt only one of the alternatives in such questions.
5. Wherever necessary, neat and properly labeled diagrams should be drawn.
SECTION - A
Q. No. 1 to 12 are multiple choice questions. Only one of the choices is correct. Select and write the correct
choice as well as the answer to these questions.
1. Big holes in Swiss cheese are made by a
(a) a machine
(b) a bacterium that produces methane gas
(c) a bacterium producing a large amount of carbon dioxide
(d) a fungus that releases a lot of gases during its metabolic activities.
2. Reema and Ajay are exploring contraceptive options. They learned that while some methods prevent
fertilization directly, others act differently. They want to know which approach does not follow the usual
contraceptive action. Which of the following approaches does not give the defined action of contraceptive?
(a) Hormonal contraceptives Prevent/retard entry of sperms, prevent ovulation and fertilisation
(b) Vasectomy Prevents spermatogenesis
(c) Barrier methods Prevent fertilisation
(d) Intra uterine devices Increase phagocytosis of sperms, suppress sperm motility and
fertilising capacity of sperms
Continue on next page.....
Page 2 Sample Paper 20 CBSE Biology Class 12
3. The age pyramid with broad base indicates
(a) high percentage of old individuals
(b) low percentage of young individuals
(c) a stable population
(d) high percentage of young individuals
4. Two closely related different species cannot live for long duration in the same niche or habitat. This law
is called
(a) Allen’s law (b) Gloger rule
(c) Competitive exclusion principle (d) Weismann’s theory
5. The feature of some structures of male reproductive system is given below. Identify the structure on the
basis of the characteristics which surrounds the primary sex organ of male reproductive system.
(a) It is responsible for maintaining the low temperature by about 2 - 2.5° C from normal body temperature
to mature sperm.
(b) It travels through the penis and carry semen as well as urine.
(c) Its enlarged end is called glans penis.
(d) Stores sperms prior to ejaculation.
6. Progestogens in the contraceptive pill
(a) checks attachment of zygote endometrium (b) inhibits estrogen
(c) prevents ovulation (d) All of the above
7. Which of the following crosses will give tall and dwarf pea plants in same proportions?
(a) TT × tt (b) tt × tt
(c) TT × Tt (d) Tt × tt
8. A sewage treatment process in which a part of decomposer bacteria present in the wastes is recycled into
the starting of the process is called
(a) primary treatment (b) activated sludge treatment
(c) tertiary treatment (d) none of these.
9. Which of the following is a plasmid?
(a) Sal I (b) Barn HI
(c) pBR322 (d) Eco RI
Continue on next page.....
NODIA APP Sample Paper 20 Page 3
10. A population has more young individuals compared to the older individuals. What would be the status
of the population after some years?
(a) It will decline. (b) It will stabilise.
(c) It will increase. (d) It will first decline and then stabilise.
11. Embryo with more than 16 blastomere formed due to in vitro fertilisation is transferred into
(a) uterus (b) fallopian tube
(c) fimbriae (d) cervix.
12. A foreign DNA and plasmid cut by the same restriction endonuclease can be joined to form a recombinant
plasmid using
(a) EcoR I (b) Taq polymerase
(c) DNA polymerase III (d) ligase
13. Assertion : Water constitutes a major mode of pollination in most of the aquatic angiospermous plants.
Reason : Vallisneria and Zostera are examples of water pollinated plants.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true and R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
14. Assertion : UAA, UAG and UGA terminate protein synthesis.
Reason : They are not recognised by tRNA.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true and R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is False but R is true.
15. Assertion : Tropical regions have got a long evolutionary time for species diversification as compared to
temperate regions.
Reason : Temperate regions have undergone frequent glaciations in the past whereas tropical regions have
remained relatively undisturbed for millions of years.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true and R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
16. Assertion : Myometrium is an important component of uterus.
Reason : Myometrium produces strong contractions during parturition.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true and R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Continue on next page.....
Page 4 Sample Paper 20 CBSE Biology Class 12
SECTION-B
17. Draw a diagram of the structure of a human ovum surrounded by corona radiata. Label the following
parts :
(i) Ovum
(ii) Plasma membrane
(iii) Zona pellucida
O
What is the function of corpus luteum ?
18. Study the graph given below and answer the questions that follows:
The curve ‘b’ is described by the following equation:
dN = K−N
dt rN & K 0
What does ‘K’ stand for in this equation? Mention its significance.
O
Which curve represent the human population growth at present? Do you think such a curve is sustainable?
Give reason in support of your answer.
19. How is genetic engineering used in molecular diagnosis of disease ?
20. How does EcoRI specifically act on DNA molecule? Explain.
Continue on next page.....
NODIA APP Sample Paper 20 Page 5
21. Given figure shows karyotype of a child who is suffering from a sex chromosomal abnormality which occurs
during failure of segregation of chromatids during cell division cycle. This results in the gain or loss of a
chromosome (s), called aneuploidy.
(i) Identify the disease from the given karyotype.
(ii) Mention the diagnostic features of this disease.
SECTION-C
22. Mention any six differences between active immunity and passive immunity.
23. The following figure shows a fetus within the uterus. On the basis of the given figure, answer the questions
that follow:
(i) Mention the role of B in the development of the embryo.
(ii) Name the fluid surrounding the developing embryo.
(iii) Identify A.
24. A person is suffering from ringworm disease. Mention the pathogen. Give the symptoms of the disease
along with the mode of transmission.
Continue on next page.....
Page 6 Sample Paper 20 CBSE Biology Class 12
25. Observe the diagram of gel electrophoresis and answer the questions which follow:
(i) Name the substance used as a medium/matrix in gel electrophoresis along with its source.
(ii) Why does DNA move towards the anode in gel electrophoresis?
(iii) How one can observe DNA in the gel after electrophoresis?
26. A decade ago, the Abingdon tortoises were abundant on the Galapagos Islands, but now this species has
become extinct.
(i) What caused their extinction?
(ii) How would you describe this kind of relationship?
O
Name and describe different hierarchial levels of biological diversity
27. (i) Identify the structure shown below.
(ii) Mention the difference in the synthesis based on the polarity of the two template strands.
28. How is detritus decomposed step-by-step by different agents and made available as nutrients to the
plants? Explain.
O
(i) Describe the events during humification and mineralisation during decomposition in the soil.
(ii) Enlist the conditions affecting the rate of decomposition.
Continue on next page.....
NODIA APP Sample Paper 20 Page 7
SECTION-D
29. Read the following and answer any four questions from 29(i) to 29 (iv) given below:
The data below shows the concentration of nicotine smoked by a smoker taking 10 puffs/ minute.
(i) With reference to the above graph explain the concentration of nicotine in blood at 10 minutes.
(ii) How will this affect the concentration of carbon monoxide and haem-bound oxygen at 10 minutes?
(iii) How does cigarette smoking result in high blood pressure and increase in heart rate?
O
How does cigarette smoking result in lung cancer and emphysema?
30. Read the following and answer any four questions from 30(i) to 30 (iv) given below:
Refer to the given figure of antibody and answer the following questions.
(i) Identify a, b and c in the given diagram.
(ii) Write the chemical nature of an antibody.
(iii) Mention the type of immune response provided by an antibody.
O
Name the cells that produce antibodies in humans.
Continue on next page.....
Page 8 Sample Paper 20 CBSE Biology Class 12
SECTION-E
31. According to Chargaff, almost all DNA-no matter what organism or tissue type it comes from maintains
certain properties, even as its composition varies. In particular, the amount of adenine (A) is usually
similar to the amount of thymine (T) and the amount of guanine (G) usually approximates the amount
of cytosine (C).
(i) A sample of DNA having 5375 nucleotides was analysed, out of which the propagation of different
bases were : Adenine = 33%, Guanine 18%, Cytosine = 33%, Thymine = 17%. What can be
concluded from this data?
(ii) If one strand of DNA has the following percentage.
A = 26%, T = 23%, C = 24%, G = 27%
What percentage will be found in the complementary strand?
(iii) If a sample of DNA has a cytosine content of 26%, what proportion of thymine do you expect?
O
Pea seeds with BB alleles have round seeds and large starch grains, while seeds with bb alleles have
wrinkled seeds with small starch grains. Work out the cross between these two parents. Explain the
phenotypic ratio of the progeny with respect to seed shape and the starch grain size of the progeny
produced.
32. Some restriction enzymes break a phosphodiester bond on both the DNA strands, such that only one end
of each molecule is cut and these ends have regions of single stranded DNA. BamHI is one such restriction
enzyme which binds at the recognition sequence, 5l -GGATCC- 3l and cleaves these sequences just after
the 5l - guanine on each strand.
(i) What is the objective of this action?
(ii) Explain how the gene of interest is introduced into a vector.
(iii) You are given the DNA shown below.
5l ATTTTGAGGATCCGTAATGTCCT 3l
3l TAAAACTCCTAGGCATTACAGGA 5l
If this DNA was cut with BamHI, how many DNA fragments would you expect? Write the sequence of
these double-stranded DNA fragments with their respective polarity.
(iv) A gene M was introduced into E.coli cloning vector pBR322 at BamHI site. What will be its impact
on the recombinant plasmids? Give a possible way by which you could differentiate non-recombinant
from recombinant plasmids.
O
(i) Write the palindromic nucleotide for the following DNA segment : 5l -GAATTC- 3l
(ii) Name the restriction endonuclease that recognises this sequence.
(iii) How are ‘sticky-ends’ produced? Mention their role.
33. Describe the role of heat, primers and the bacterium Therm us aquaticus in the process of PCR.
O
Why is a recombinant protein so called? How can it be harvested on a large scale? Write two precautions
to maintain a higher yield.
******
