LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

ED 18

B.Sc. DEGREE EXAMINATION – PLANT BIOLOGY & PLANT BIO-TECH.

FIFTH SEMESTER – November 2008

PB 5506/ PB 4500 – GENETICS AND PLANT BREEDING

 

 

 

Date : 05-11-08                     Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

PART – A                                                      (20 marks       

 

Answer ALL questions                                                                                              (5 x 1 = 5 marks)

 

1. Choose the correct answer.

 

1. A cross of the F₁ with the recessive parent is known as

1. a) Test cross b) back cross c) Single cross            d) double cross.

1. Hereditary variations in plant can be produced by

1. a) Auxins b) X-ray                       c) Kinetin                    d) Heat.

1. A co-ordinated unit which controls the genetic expression

1. a) cistron b) recon c) operon        d) muton

1. The thoery of inheritance of acquired characters was proposed by

1. a) Darwin b) Weisman c) Mendel                    d) Lamarck.

1. The process of mating of individuals which are more closely related than the average of the population to which they belong is called

1. a) In-breeding b) Hybridization          c) self breeding           d) Heterosis.

 

1. State whether the following statements are True or False (5 x 1 = 5 marks)

 

6. Continuous variations are attributed to crossing over.
7. In E.coli Lac operon is induced by lactose.
8. Gene mutation is caused due to change in sequence of nitrogen bases.
9. The monoallelic heterozygous plant producer only one gamet.
10. Devries theory of evolution is based on discontinuous variations.

 

III. Complete the following                                                                                  (5 x 1 = 5 marks)

 

1. Smallest unit which may cause mutation is ___________
2. Mutations in plants are induced by __________
3. Unit of distance between genes on the chromosome is _________
4. The F₂ phenotypic ratio for a dihybrid cross is _________
5. The term pureline was first introduced by _________

 

1. Answer ALL questions, each within 50 words (5 x 1 = 5 marks)

 

16. What is Heteroploidy?
17. Define termination codons
18. What is polygenic inheritance?
19. Define heterosis.
20. What is emasculation?

PART – B

Answer any FIVE each within 350 words.

Draw diagrams wherever necessary.                                                                     (5 X 8 = 40 marks)

 

1. Briefly describe the sex determination in plants.
2. Explain cytoplasmic inheritance with suitable example.
3. Write notes on the objectives of plant breeding.
4. Describe the pureline selection.
5. Briefly explain the principles of Lamarckism.
6. Discuss about klinfelters syndrome.
7. Write notes on mutagens.
8. Give an account of post transcriptional modifications.

 

PART – C

 

Answer the following each with in 1,500 words.

Draw diagrams wherever necessary.                                                                           (2 x 20 = 40 marks)

 

1.  a) Write an essay on chromosomal aberrations.

(OR)

1. b) Explain in detail the strucure and organization of DNA.

 

30. a) Explain how gene expression can be regulated in E.Coli with suitable example.

(OR)

1. b) Explain the following

(i) Transposable elements

(ii) Lethal genes

(iii) Hybridization.

 

 

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