Max Marks : 70
Time allowed : 3 hrs

Section A

Q. Nos. 1-8 are of very short answer type carrying one mark each. Answer them in 1-20 words each.

Q1. Name the process in which bacteriophage picks-up a piece of DNA from one bacterial cell and transfers the same to another bacterial cell on infection.

Q2. Which fraction of soil water is readily available to plants for absorption?

Q3. What protects nitrogenase?

Q4. Name two plants that produce rhizomes.

Q5. Why is oxytocin called as ‘Birth Hormone’?

Q6. From which germ layers do the following organs differentiate :
(i) Kidney
(ii) Urinary bladder

Q7. What provides energy for abiotic synthesis on the primitive earth?

Q8. Name the two curable sexually transmitted diseases.

Section B

Q. Nos. 9-18 are short answer questions carrying 2 marks each. It is appropriate to answer them in about 20-30 words.

Q9. In most plants the terminal bud suppresses the development of lateral buds. What is this phenomenon called? Name the phytohormone that can promote the phenomenon.

Q10. Sieve tubes in angiosperms are associated with specialised parenchyma cells. Name those cells. How do they help sieve tube members?

Q11. How is the digested fat absorbed?

Q12. What are antagonistic muscles? Give one example.

Q13. Describe the methods of birth control by which fertilisation of ovum by sperm is prevented.

Q14. What is artificial selection in terms of evolution? Name one plant that has been produced as a result of artificial selection.

Q15. ‘Birds have evolved from reptiles’. How does palaentology provide evidence in support of the above statement?

Q16. Who discovered the coacervates? List the biological properties of co-acervates.

Q17. What is mycorrhiza? How does it act as biofertiliser?

Q18. Define autoimmune diseases. Give two examples.

Section C

Q. Nos. 19-27 are short answer questions carrying 3 marks each. It is appropriate to answer them in about 30-50 words.

Q19. What is transformation? Describe Griffith’s transformation experiment.

Q20. What are linked genes? Diagrammatically represent a cross between a white eyed female and red eyed male drosophila.

Q21. How does an excess of tryptophan cause ‘Switching off’ of the ‘tryptophan operon’?

Q22. If abiotic origin of life is in progress on a planet other than earth, what should be the condition there? Explain.

Q23. Trace the formation of Ovum from oogonium.

Q24. Describe the role of red blood cells in the transport of oxygen and carbon dioxide by blood.

Q25. Draw a diagram to show the internal structure of the human heart. Label six parts in all including at least three valves.

Q26. What is metastasis? List any four danger signals of cancer.

Q27. By providing one example for each category, classify the angiospermic flowers based on the position of ovary.

Section D

Q. Nos. 28 – 30 are long answer questions carrying 5 marks each. It is appropriate to answer them in about 80 – 120 words each.

Q28. Describe the process of DNA replication.

Q29. Specify how C₄ photosynthetic pathway increases CO₂ concentration in bundle sheath cells of sugarcane. How much is C₄ pathway more energy-expensive than C₃ pathway?

Q30. What is a synapse? How is the nerve impulse transmitted across a synapse?