Section - A

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

Q 1. What is meant by trisomic condition? 1 mark


Q 2. State the presence or absence of sinus venous in a fish and a mammal. 1 mark


Q 3. Which type of cartilage is present between vertebrae to allow limited movement? 1 mark


Q 4. Name any two breeds of wild rock pigeon that have been developed through artificial selection. 1 mark


Q 5. Which chromosomes are called autosomes? 1 mark


Q 6. When is a tumour referred to as malignant? 1 mark


Q 7. What are the two factors that contribute for the dissociation of oxyhaemoglobin in the arterial blood to release molecular oxygen in an active tissue? 1 mark


Q 8. Which one of the following is fatal unless oral rehydration therapy is administered:
(i)  (ii) Cholera (iii) Tetanus 1 mark

Section - B

Q. Nos. 9-18 are of short answer type carrying 2 marks each. Answer them in approximately 20-30 words each.

Q 9. What are the two functions of DNA polymerase? 2 marks


Q 10. Stanley Miller and Harold C. Urey performed an experiment by recreating in the laboratory the probable conditions of the atmosphere of the primitive earth.


(i) What was the purpose of the experiment?
(ii) In what forms was the energy supplied for the chemical reactions to occur?
(iii) For how long was the experiment run continuously? 2 marks

Q 11. How does the mustard inflorescence differ from the banana inflorescence in arrangement? Give the technical term for each. 2 marks


Q 12. Name the basic nitrogenous catabolite of proteins produced in birds. In what form is it eliminated from their body? What is the advantage of this type of excretion? 2 marks


Q 13. Describe the theory of inheritance of acquired characters. Who disproved it experimentally? 2 marks


Q 14. Differentiate between morula and blastula of mammals. 2 marks


Q 15. What is the biological significance of Azolla pinnate in agriculture? 2 marks


Q 16. Give any two reasons to justify that ginger is a modified stem. 2 marks

Q 17. Define biogeography. How do Darwin's Finches provide the biogeographical evidence in favour of evolution? 2 marks


Q 18. Explain the structural and functional significance of fovea in the human eye. 2 marks

Section - C

Q. Nos. 19-27 are of short answer type carrying 3 marks each. Answer them in approximately 30-50 words each.

Q 19. What is meant by R cells and S cells with which Frederick Griffith carried out his experiments on Diplococcus pneumoniae? What did he prove from these experiments? 3 marks


Q 20. Draw a diagram of the T.S. of a part of seminiferous tubule of testis of an adult human male and label any six parts in it.


Q 21. How does industrial melanism bring out the action of natural selection? 3 marks


Q 22. How does intestinal juice contribute in the digestion of proteins? What provides alkaline pH in the small intestine? 3 marks


Q 23. An mRNA strand has a series of codons out of which three are mentioned below.

(i) AUG, (ii) UUU and (iii) UAG
(a) What will these codons be translated into?
(b) What are the DNA codons that would have transcribed these RNA codons? 3 marks

Q 24. List any four symptoms shown by a Down's syndrome afflicted child. Explain the cause of this disorder. 3 marks


Q 25. Answer the following with reference to the anatomy of a dicot stem :

(i) Where exactly are the cambial cells located in the vascular bundles?
(ii) What is the name given to such a bundle?
(iii) How are the xylem vessels arranged?
(iv) What type of cells constitute the pith? 3 marks

Q 26. Explain any three chemical barriers that offer a non-specific defence mechanism. 3 marks


Q 27. Trace the development of microsporocyte in the anther of a mature pollen-grain. 3 marks

Section - D

Q.Nos. 28-30 are long answer type carrying 5 marks each. Answer them in approximately 80 - 120 words each.

Q 28. In the case of snapdragon (Antirrhinum majus) a plant with red flowers was crossed with another plant with white flowers. Trace the inheritance of flower colour up to the F₂ generation indicating the genotypesand phenotypes at each level. What special feature do you note in the genotypic ratios in the F₂ generation? 5 marks


Q 29. Name the hormone that regulates each of the following and mention the source of it :

(i) Urinary elimination of water

(ii) Storage of glucose as glycogen

(iii) Sodium and potassium ion metabolism

(iv) Basal metabolic rate

(v) Descent of testes into the scrotum 5 marks

Q 30. Describe the C₄ pathway in a paddy plant. How is this pathway an adaptive advantage to the plant? 5 marks