class 12 cbse biology sample paper model 1 - http://cbse.edurite.com/cbse-sample-papers/cbse-sample-papers-for-class-12.html

1. Sample Question Paper
Biology
Class – XII
Time: 3 hrs.
M.M.: 70
General Instructions:
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(i) All questions are compulsory.
(ii) This question paper consists of four sections A, B, C and D. Section A contains 8
questions of one mark each, Section B is of 10 questions of two marks each, Section C is
of 9 questions of three marks each and Section D is of 3 questions of five marks each.
(iii) There is no overall choice. However, an internal choice has been provided in one
question of 2 marks, one question of 3 marks and two questions of 5 marks weightage. A
student has to attempt only one of the alternatives in such questions.
(iv) Whenever necessary. The diagrams should be neat and properly labeled.
(1x 8 = 8)
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Section-A
1. “Tanmay suffered from measles at the age of 10 years. There are rare chances of his getting
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infected with the same disease for the rest of his life.” Give reason for the statement.
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2. The meiocyte of an onion plant contains 32 chromosomes. Workout the number of
chromosomes found in its endosperm.
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3. What is Baer’s law?
4. In the Whiptail lizards only females are born generations after generation. There are no
males. How is this possible?
5. Mention any two measures for prevention and control of alcohol and drug abuse among
adolescents.
6. Name the world’s most problematic aquatic weed. What is the nature of the water-body in
which weeds grow abundantly?
7. Name the embryonic stage that gets implanted in the uterine wall of a human female.
8. Write the difference between net primary productivity and gross productivity.

2. Section-B
(2x 10 =20)
9. The cell division involved in gamete formation is not of the same type in different
organisms. Justify.
10. Differentiate between benign and malignant tumors.
11. What is emasculation? Explain its importance in hybridization?
12. Differentiate between euchromatin and heterochromatin.
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13. In which technique we use Taq polymerase enzyme and why?
14. How do Darwin’s finches illustrate adaptive radiation?
15. Name the blank spaces a, b, c and d from the table given below:
Type of Microbe
Scientific Name
Commercial Product
Bacterium
a
Lactic acid
Fungus
b
c
Monascus purpureus
Statin
Fungus
Penicillium notatum
d
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Cyclosporin A
16. Draw a vertical section of maize grain and label.
(i) Pericarp, (ii) Scutellum, (iii) Coleoptile, and (iv) Radicle.
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17. When a red flowered Antirrhinum plant was crossed with a white flowered Antirrhinum
plant, the F1 – offspring had pink flowers. Mention –
(a) Genotype of F1 plant.
(b) The reason why it did not beat the parental red or white flower colors?
18. Explain the dual function of AUG codon. Give the sequence of bases it is transcribed from
and its anticodon.

3. Section-C
(3x9=27)
19. A non-haemophilic couple was informed by their doctor that there is possibility of a
haemophilic child be born to them. Explain the basis on which the doctor conveyed this
information. Give the genotypes and the phenotypes of all the possible children who could
not be born.
20. Draw a diagram of a male gametophyte of an angiosperm. Label any four parts. Why
sporopollenin is considered the most resistant organic material?
to them?
22. Explain briefly the types of thalassemias.
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21. How do you explain to the farmers that apiculture is both easy and economically beneficial
23. How does a plant breeder ensure cross-pollination in economically important bisexual
flower?
24. Name the malaria parasite. Where do the gametocytes of this parasite develop? Give a flow
chart of its life-cycle in this host.
the embryos of vertebrates?
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25. Plasmid is a boon to biotechnology and conclusions made by Baer Ernst Haeckel on studying
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26. Describe different types of natural selection that causes allele frequencies of a population
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to change.
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27. Explain the causes of Global Warming? Why is it a warning to mankind?
Section-D
28. (a) Mention the role of vectors in Recombination DNA technology. Give two examples.
(c) With the help of diagrammatically representation only, show the steps of Recombinant
DNA technology.
[5]
29. If a desired gene is identified in an organism for some experiments, explain the process of
the following:
(i)
Cutting this gene at specific location.
(ii)
Synthesis of multiple copies of this desired gene.

4. 30. Modern scientists accept evolution and natural selection as natural phenomena. The
mechanism of evolution under modern concept has been explained n the basis of
(Value based Question)
“Population dynamics”.
What is population dynamics?
[1]
(ii)
What is the ultimate source of organic variation?
[1]
(iii)
How evolution is explained in terms of modern scientists?
[2]
(iv)
How a new species is formed?
[1]
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(i)