ALL KERALA BHAVAN’S MODEL EXAMINATION 2023-2024
BIOLOGY( 044)
SET III
Std: XII
Max.marks:70
Time : 3hrs
General Instructions:
(i) All questions are compulsory.
(ii) The question paper has five sections and 33 questions. All questions are compulsory.
(iii) 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.
(iv) 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.
(v) Wherever necessary, neat and properly labeled diagrams should be drawn.
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Qno Question AR Mark
SECTION A
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1. The cells of endosperm have 24 chromosomes. What will be the number of chromosomes in 1
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the gametes?
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a) 8 b) 16 c) 23 d) 32
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2. Plants with ovaries having only one or a few ovules , are generally pollinated by 1
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a) Bee b) Butterfly c) Birds d) Wind
3. There are three genes a, b, c. Percentage of crossing over between a and b is 20%, b and c is 1
28% and a and c is 8%. Analyse the percentage of crossing over between different genes
and choose the correct option of the sequence of genes on chromosomes.
a) b, a, c b) a, b, c c) a, c, b d) none of these
4. DNA consists of two complementary polynucleotide chains. If the sequence of nucleotides 1
in one of the chains is AGCTTCGA, then the nucleotide sequence in the other chain shall
be
a) TAGCATAT b) TCGAAGCT c) GATCCTAG d) GCTAAGCT
5. Given below are the events that are observed in an artificial hybridization programme. 1
Arrange them in the correct sequential order and select the correct option .
i. Rebagging.
ii. Selection of parents .
iii. Bagging.
iv. Dusting the pollen on stigma
v. Emasculation
vi. Collection of pollen from male parent.
a) 2- 3- 5- 6- 4- 1. b) 2- 5- 3- 6- 4- 1
c) 5- 2- 3- 6- 1- 4 d) 2- 3- 6- 4- 5- 1
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6. AR
The fact that a purine base always paired through Hydrogen bonds with a pyrimidine base 1
leads to…….. in the DNA double helix.
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a) The antiparallel nature.
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b) The semiconservative nature
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c) Uniform width throughout DNA
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d) Uniform length in all DNA
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7. In a population of 1000 individuals 360 belong to genotype AA, 480 to Aa and the 1
remaining 160 to aa . Based on this data, the frequency of allele A in the population is
a) 0.4 b) 0.5 c) 0.7 d) 0.6
8. Dinosaurs were present during: 1
a) Palaeozoic era b) Mesozoic era c) Cenozoic era d) Proterozoic era
9. Given below is the diagram of human lymphatic system where A, B, C and D are lymphoid 1
organs .Select incorrect option regarding the lymphoid organs labeled as A, B, C and D
a) T cells mature in B.
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b) B and T cells undergo maturation in C. AR
c) B and T cells undergo proliferation and differentiation in A.
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d) B cells mature in D.
α-1 antitrypsin is
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10. 1
a) an antacid b) used to treat arthritis
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c) an enzyme d) Used to treat emphysema
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11. Match column I with column II and select the correct codes from the options given below: 1
Column I Column II
A. Rosie i) High yield pest resistant
B. Bt.cotton ii) Safety of polio vaccine
C. Transgenic mice iii) Protein enriched milk
D. ADA deficiency iv) Gene therapy
a) A-iii, B-ii, C-i, D-iv b) A-iii, B-i, C-iv, D-ii
c) A-i, B-ii, C-iii, D-iv d) A-iii, B-i, C-ii, D-iv
12. What kind of pyramid is represented by the given figure ? 1
a) Pyramid of numbers in forest ecosystem.
b) Pyramid of numbers in a parasitic food chain
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c) Pyramid of biomass in forest ecosystem. AR
d) It is a wrong pyramid.
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Question no 13 to 16 consists of two statements Assertion (A) and Reason (R). Choose
the correct options for the following questions:
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a) Assertion and reason both are correct and reason is the correct explanation of
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assertion.
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b) Assertion and reason both are correct but reason is not the correct explanation of
assertion.
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c) Assertion is correct and reason is wrong.
d) Assertion is wrong but reason is correct
13. Assertion : Organisations like GEAC are necessary to monitor GM researches and test the 1
safety of introducing GM organisms for public services.
Reason : GM researches can have unpredictable results which even can be disastrous when
genetically modified organisms are introduced into the ecosystem
14. Assertion: Exalbuminous seeds do not possess any residual endosperm, as it is completely 1
cosumed during embryo development.
Reason : Wheat, castor,pea and groundnut are all examples of ex-albuminous seeds.
15. Assertion: DNA is considered to be a better genetic material than RNA for most organisms. 1
Reason: 2’- OH group present in DNA makes it labile and less reactive .
16. Assertion: Opioids help to enhance respiratory activity. 1
Reason: Opioids are the drugs which binds to the specific opioids receptors present in
central nervous system.
SECTION B
17. Study the table given below in regard to population interactions and answer the questions
that follow:
Species A Species B Name of
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interaction
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_ 0 (A)
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+ _ (B)
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_ _ (C) 2
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+ + (D)
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a) Identify the interactions (A) to (D).
b) Explain interaction (A)
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There are many animals that have become extinct in the wild but continue to be maintained
in zoological parks.
a) What type of biodiversity conservation is observed in this case?
b) Explain any other two ways which help in this type of conservation.
18. a) A specific gene from Bacillus thurengensis was introduced in a plant to control 2
infestation by corn borer. Name
i) the gene introduced
ii) the resultant plant after successful insertion of the desired gene
b) What are transposons?
19. The histogram given below represents the data for the annual shark harvest in the Great 2
Barrier reef / coral reef located on the east coast of Queensland, Australia. Study the
histogram and answer the questions that follow:
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a) Write your interpretation of the data given.
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b) Write the impact on the biodiversity of the area that you can interpret on the basis of
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the data.
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20. Carefully observe the given structure and answer questions that follows: 2
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a) Name the compound obtained from the given plant.
b) Which part of the plant is used to obtain the drug.?
c) What are the major effects of the compound obtained from the given plant?
21. a) Select the analogous structures from the combinations given below:
i) Forelimbs of whales and bats.
ii) Eyes of octopus and mammals.
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iii) Tubes of sweet potato and potato
iv) Thorns of Bougainvillea and tendrils of cucurbita
b) State the kind of evolution they represent.
SECTION C
22. List three strategies that a bisexual chasmogamous flower can evolve to prevent self 3
pollination.
23. a) Draw a labelled diagram of the embryonic stage that gets implanted in the human uterus. 3
b) State the functions of the two parts labelled.
Or
Construct a flow chart exhibiting sequential events of oogenesis.
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24. Illustration given below is a DNA segment which constitute a gene. 3
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BR
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i) Name the shaded and unshaded regions of the gene.
ii) Explain how these genes are expressed?
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iii) How are these genes different from prokaryotic gene in its expressions?
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a) “Complete lactation is a natural method of contraception.” Justify this statement.
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25. 3
b) A proper understanding of menstrual cycle can help immensely in family planning. Do
you agree with this statement? Provide reasons for your answer.
26. a) Identify the figure given below: 3
b) Name the initial cell from which the structure has developed.
c) Draw the next mature stage.
d) Endosperm development precedes embryo development. Explain the reason.
27. In the given figure A and B represent different forms of proteinaceous hormone secreted by 3
pancreas in mammals.
a) Name the hormone. What type of bonding is present between chains of this hormone?
b) How do these two forms differ from each other?
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c) Explain how this hormone was produced by Eli lily an American company, using rDNA
technology.
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28. Carefully observe the image given below that illustrates secondary treatment of sewage 3
water and answer the questions:
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a) what is represented by A and B in the diagram?
b) Why is air pumped through A? When is the effluent passed from A to B?
c) What is activated sludge and how is the surplus sludge further treated?
SECTION D
29. In this autoradiograph, the ladder sequence measures approximately 1200 base pairs, which 4
band will correspond to 600 bp?
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ii) On what basis the fragments get separated like this during gel electrophoresis? Mention
one significance of this technique while conducting a recombinant experiment.
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iii) Elaborate the step followed to visualize the DNA bands.
Or
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Why does DNA move towards the anode in gel electrophoresis? Which is the commonly
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used matrix in this process of separation?
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30. Given below is a diagrammatic representation of the experimental set up used by S L Miller 4
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for his experiment.
i) Write the names of different gases contained and the conditions set for the reaction in the
flask A.
ii) State the type of organic molecule he collected in water at B.
iii) Write the conclusion he arrived at.
SECTION E
31. a) Cancer is one of the most dreaded diseases of humans. Explain ‘contact inhibition’
and ‘Metastasis’ with respect to the disease.
b) Name the group of genes which have been identified in normal cells that could lead
to cancer and how they do so? 5
c) Name any two techniques which are useful to detect cancers of internal organs.
d) Give reason why cancer patients are often given α- interferon as part of the
treatment.
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Malarial parasite ‘Plasmodium’ completes its life cycle in two hosts. Draw its
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complete life cycle and explain various stages it follows through out its life.
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32. Following the collision of two trains a large number of passengers are killed. A majority of 5
them were severely burnt beyond recognition. Authorities want to hand over the dead to
their relatives.
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a) Name a modern scientific method and write the procedure that would help in the
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identification of kinship.
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b) Mention the scientist who developed this procedure.
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c) List any two applications of this procedure other than mentioned above.
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a) Draw a labelled diagram of a “replicating fork” showing the polarity. Why does
DNA replication occur within such ‘forks’?
b) Name two enzymes involved in the process of DNA replication, along with their
properties.
33. The graphs (X) and (Y) below depict the diurnal variations in the solar radiations in the 5
month of June (summer) and in December (winters):
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a) Which of the two graphs depict tropical region and temperate regions
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respectively?
b) Which of the two regions (X) or (Y) will show high biological diversity and why?
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c) How is the presently occurring sixth episode of mass extinction different from the
previous five episodes? Also state the reason for it.
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Or
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a) Draw a ‘pyramid of numbers’of a situation where a large population of insects
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feed upon a very big tree, the insects in turn are eaten by small birds which in
turn are fed upon by big birds.
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b) Differentiate giving reason, between the pyramid of biomass of the above
situation and the pyramid of numbers that you have drawn.
c) Mention any two shortcomings of ecological pyramids in the study of ecosystem.
