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NATIONAL OPEN UNIVERSITY OF NIGERIA
UNIVERSITY VILLAGE, PLOT 91, CASDASTRAL ZONE, NNAMDI AZIKIWE EXPRESS WAY, JABI, ABUJA.
FACULTY OF SCIENCES
JULY 2018 EXAMINATION
BIO309: Plant Breeding
Time: 2 hours
Credit Unit: 1 Unit
Instructions: Answer 4 questions only .Question 1 is compulsory
1a. Mention 4 adverse effects of inbreeding in animals (6marks)
1b. State the four categories of Plant breeding methods and the type(s) of crops involved in each. (6 marks)
1c. Elucidate the genetic basis of heterosis (13marks)
2a. List 4 traits which plant breeders have tried to incorporate into their crops in the last century (6marks)
2b. Explain the term ‘Wide crosses’ (9marks)
3a. Complete the following table (5marks; 0.5 for each)
|
Name of Organism |
No of Gametic chromosomes |
No of Somatic chromosomes |
|
Man |
23 |
|
|
Onion |
|
16 |
|
Drosophila |
4 |
|
|
Cotton |
|
52 |
|
Garden pea |
7 |
|
|
Rice |
12 |
|
|
Tomato |
|
24 |
|
Wheat |
21 |
|
|
Maize |
10 |
|
|
Haplopappusgracilis |
|
4 |
3b. Based on the position of the centromeres, name and describe the 4 groups of the chromosomes (10 marks)
4a. Enumerate 2 practical uses of coefficient of inbreeding (3 marks)
4b. Explain the term ‘inbreeding depression’ (4marks)
4c. Write a short note on ‘coefficient of inbreeding’ (F) (8 marks)
5a. List four types of self-incompatibility (4 marks)
5b Justify the role of self-incompatibility in the success of angiosperms (11 marks)
