Class XII: Biology – 2007

January 7, 2009 by  
Filed under Class XII Question Papers

SECTION-A

1. A potted plant otherwise kept in sunlight, is shifted to monochromatic red light (wave length 700nm). Will the rate of photosynthesis increase, decrease or remain the same? (1 mark)

2. Name two non-iron products of the breakdown of haemoglobin. (1 mark)

3. Flowers that bloom at night are usually small and white but give out a strong scent. Why do they do so ? (1 mark)

4. Rearrange the following levels in their correct organisational sequence : Landscape, Organism, Community, Population Ecosystem, Biosphere. (1 mark)

5. During a meristem culture some explants were kept in culture medium containing more of auxins than cytokinins. Which organ of the plant is expected to differentiate from the callus? (1 mark)

SECTION-B

6. Name the enzyme that catalyses carboxylation as well as oxygenation reaction. In which cell organelle, is this enzyme found and in what way, is that organelle different in the mesophyll and bundle sheath cells? (2 marks)

7. How do the potassium, chloride and malate ions help in opening the stomata ? (2 marks)

8. Two green potted plants were kept separately inside oxygen free bell jars, one in sunlight and the other in dark. Which of the two plants will survive for longer period and why? (2 marks)

9. A student unknowingly crushed a cockroach under his shoes. Finding that no red fluid comparable to vertebrate blood came out, he was curious to know whether the cockroaches are at any disadvantage. How will you satisfy his curiosity? (2 marks)

10. Show by a series of diagrams the manner of regeneration in a hydra if it is cut into two pieces transversely at the middle. (2 marks)

OR

Show by a series of diagrams the manner of transverse binary fission in Planaria. ( 2 marks)

11. In extreme summer and winter, certain animals like frogs and lizards abandon active life. This is popularity called summer sleep and winter sleep respectively. (2 marks)

(i) What are the technical terms for summer sleep and winter sleep?

(ii) State any two changes in the body that occur during the above-mentioned dormant states.

12. State the relationship between biotic potential and environmental resistance. (2 marks)

13. Define parthenogenesis. Give one example of parthenogenesis from plants and one from animals. (2 marks)

14.What is meant by active immunity and passive immunity? (2 marks)

15. A person was born without thymus gland but otherwise normal. Mention any four ways in which the person is likely to suffer due to its absence. (2 marks)

SECTION-C

16. Mr. ‘X’ hardly fell sick when young. As he aged and grew older he started contracting many infectious diseases. (3 marks)

(i) Name the theory of ageing which explains the above mentioned change.

(ii)What causes susceptibility to infections in old age?

17. How many pairs of ribs are found in the humans? How do you categorise these on the basis of their attachment ? Explain. (3 marks)

18. Stomach is the right place in the alimentary canal where hydrochloric acid is secreted in the gastric juice. Describe any three points to justify this statement. (3 marks)

19. Suppose for some reason ATP falls deficient in a nerve fibre, how will it affect the conduction of nerve impulse through it? (3 marks)

20. Giving an example of CAM plants, explain the process of Crassulacean Acid Metabolism. What is its advantage? (3 marks)

OR

Starting from Glycolate produced in the chloroplast, explain the various steps of photorespiratory pathway that take place in the two other organelles up to the formation of PGA back in the chloroplast. (3 marks)

21. Differentiate between morula and blastocyst as stages in human embryonic development. Which of these stages gets implanted in the uterine wall and about how many days after fertilization? (3 marks)

22. Name the three major Biomes and state the kind of climax vegetation found in each of them. (3 marks)

23. Name and define the environment-related terms for the following: (3 marks)

(i) Pertaining to the fact that DDT accumulated in a three step food chain will be maximum in the secondary consumer.

(ii) Pertaining to causing algal bloom.

24. List and briefly describe any three diagnostic techniques by images based on the use of ‘X’-rays. (3 marks)

25. In regard to transplant of organs, what are isograft, allograft and xenograft? (3 marks)

SECTION-D

26. Name any two C4 plants. Specify how the C4 photosynthetic pathway increases C02 concentration in bundle sheath cells of such plants and explain what is the need of increasing C02 concentration. (5 marks)

OR

(a) Name two organisms whose symbiotic association leads to nitrogen fixation in root nodules. (2 marks)

(b) Describe the steps in the formation of root nodules and name the two plant harmones that promote cell division for nodule formation. Which two physiological processes provide the FAD and ATP required for fixation of atmospheric nitrogen? (3 marks)

27. Decribe the structure of immunoglobin or Ig/antibody. Draw a diagram show­ing the formation of antigen-antibody complex and label the parts. (5 marks)

OR

(a) Define the following : (3 marks)

(i) a protoplast

(ii) a somatic hybrid

(iii) an allopolyploid

(b) With the help of diagrams, describe the formation of a somatic hybrid cell. (2 marks)

28. Differentiate between osmoregulators and osmoconformers. How will you categorise humans, hagfish, and camel under these categories? Mention any four points how camel regulates the water content of its body. (5 marks)

OR

Trace the events in a muscle fibre from the time it receives the impulse through the neuromuscular junction up to the contractile response. (5 marks)

Table of contents for CBSE XII Papers 2007

  1. Class XII: Biology – 2007

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