LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc., DEGREE EXAMINATION – PLANT BIO. & BIO TECH.
FIFTH SEMESTER – SUPPLEMENTARY – JUNE 2012
PB 5516/PB 5510 - GENETICS, PLANT BREEDING AND EVOLUTION
Date : 27-06-2012
Time : 2:00 - 5:00
Dept. No.
Max. : 100 Marks
PART – A
Answer the following, each within 50 words only:
(10x2=20)
1. What are Lethal genes?
2. What are Multiple alleles?
3. Define Cistron.
4. What is Stop codon?
5. Write short notes on Poly Ploidy.
6. What is Photo reactivation?
7. Define Domestication.
8. What is clonal selection?
9. Define Speciation.
10. What is organic evolution?
PART – B
(5x7=35)
Answer each of the following questions within 500 words.
Draw diagrams wherever necessary.
11. a) Explain the law of Independent Assortment citing an example.
(OR)
b) With a suitable example, explain codominance in plants.
12. a) How is the lac operon regulated in E.Coli?
(OR)
b) What is transcription? Explain the process of transcription.
13. a) Briefly explain the different types of mutation.
(OR)
b) Give an account of chemical mutagens and their properties.
14. a) How is the F 1 generation obtained through the process of hybridization?
(OR)
b) List out the positive and negative effects of heterosis.
15. a) Discuss about mutation theory.
(OR)
b) Critically comment on Neo-Lamarckism
PART – C
Answer any three of the following questions within 1200 words each:
Draw diagrams wherever necessary.
16. What is a dihybrid cross? Explain with the help of punnet square.
17. Enumerate the process of translation with suitable diagrams.
18. Explain in detail the different light –independent DNA repair mechanisms.
19. Discuss the methods of mass and pure line selection.
20. Discuss the principles of natural selection. Comment on the merits and demerits.
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(3X15=45)