1.· Answer any ten of the following in about 60 words each 6xlO=60

Write a-note on cell theory.


Point out the differences and similarities between mitochondria and chloroplasts;


Explain the importance of linkage and crossing-over.


Do you think that mutation has any role in crop improvement? Explain.


Explain hybrid vigour.


Explain the role of tRNA in protein biosynthesis.·


What are the pigments present in plants? How does chlorophyll differ from haemoglobin?


What measures should be taken to conserve plant genetic resources?


What is sex-linked inheritance? Explain.


Write a note on the centre of origin of crop plants.


How does C4 photosynthesis differ from C3 photosynthesis?


2.
Discuss the mechanism of absorption and translocation of water in plants. 60

3.
Define photosynthesis. In the light of modern research, explain-the mechanism of light-dependent reactions of photosynthesis. 60

4.
Describe the double helical structure of deoxyribonucleic acid. What are the biological functions of DNA?

5. Answer any ten of the following in about 60 words each

What are the'differences between growth and development?


Define plant hormones and show how they are different from vitamins.


How do molybdenum and boron deficiency affect cole crops? What· measures are taken to control such deficiency?


What are the common ascorbic-acid rich fruits grown in Assam? How are they important in maintaining normal health of people?


What is biological control of pests? Is it advantageous over chemical methods?


What are the different types of chemical pesticides? How are they toxic to people? Which one is persistent in the environment?


"Biological organisms high on the food chain to potentiall:r leveha of persistent toxicants." Explain.


What is

What is the impgrtance of pruning of fruit trees?


What is fm How does an auxin work?


What the changes that occur during ripening of fruits? Explain the role gf ¢thylene in fruit ripening.


6.
Write an essay on the biological impact of pesticides. 60

7.
Defme germination dormancy. What biochemical changes occur durina the germination of seeds? Describe the methods adopted to break dormancy of seeds, 60

8.
Descrihe the principal methods e!llployed for the preservation of fruits. What are temporary ancl permanent preservations? 60·




2 12RQ-IOO