Saturday, December 22, 2007

SAMPLE PAPER-Class: XII Sub: Biology


Instructions: As usual

The discovery of an enzyme revolutionized the field of genetic engineering and changed the central dogma of molecular biology in 1975. Name the enzyme and the reaction catalyzed by it?
Name the process of rupture of Graffian follicle and the subsequent release of egg from the ovary.
What name is given to the type of growth that assumes a sigmoid curve?
Which type of immunity is provided by vaccination?
Mention the two key concepts of Darwinism?
What do the oral contraceptive pills contain?
How is maize plant adapted for anemophily?
Name the two richest zones of biodiversity in India.


9. What are sacred groves? What is their role in conservation of biodiversity?
10. How is phosphorus cycle different from carbon cycle?
11. The gene for Hemophilia doesn’t pass from father to son or from mother to daughter. Name the type of inheritance and explain the mechanism.
12. What is the processing of hnRNA? Why is it necessary in eukaryotes?
13. Name the two types of cells present in the inner lining of seminiferous tubule. What are their functions?
14. What are the drawbacks of conventional insulin? How does transgenic insulin overcome these?
15. What is tapetum? What is its role in the developing anther?
16. Workout the possible genotypes and phenotypes in the offspring produced in a cross between a red flowered (homozygous) and a white flowered (homozygous) 4O’clock plant. Name the type of inheritance shown by the cross.
17. What are the characteristics of acquired immunity? Which of these is exploited in vaccination?
The base sequence on one of the strands of DNA is-
(a). Write the base sequence of its complementary strand.
(b). What will be the sequence of mRNA transcribed on it?
18. Name the labeled parts of the given diagram.


19. What are Cry proteins? Name an organism that produces them. How is it being used in
crop protection?
20. What are the exceptions of Mendel’s law of Independent assortment? Why were these
not detected by Mendel?
21. Bring out the salient features of Genetic code. Why is the code said to be degenerate?
(a). What are methanogens?
(b). How are biofertilizers more advantageous over traditional fertilizers?
23. How can one prove Darvinian theory of Natural selection true by putting forward an
example? Explain.
24.What are statins? Where are they produced? How are they useful to man?
25. What is corpus luteum? Mention its role as an endocrine gland?
26.What are the activities included in ex situ strategies of conservation of biodiversity?
27. How are the autoimmune diseases different from immunodeficiency diseases? Give
examples of each.
What are interferons? Which type of immunity do they provided? Explain.


28. Where do the transcription and translation occur in a cell? Explain the process of
translation in eukaryotic cell.

What is Lac oparon? How is the operator switched on or off in the expression of genes in
this oparon?
29. (a).What are algal blooms? How are they formed?Give two harm ful effects of it in a
water body.
(b). Why does biomagnification occur with some substances? Give example
(a).What is Jhum cultivation? Explain how it is responsible for deforestation.
Describe organic farming.
Name the most common method of removal of particulate air pollutants.
30.(a) Why is autogamy discouraged in plants? Memtion any four adaptations to ensure xenogamy.
(b).Draw a labeled diagram of V.S. of a maize grain.
Where and when does oogenesis take place in human female? Describe the events of female reproductive cycle.