GPB (506)Population Genetics (Question Paper )

  

  

Q1) Derive the following (7 marks)

a) Inbreeding coefficient in a population subjected to restricted random mating

b) Derive any two of the following

i) Response to selection shown by loci showing additive gene action in maize

ii) Determining inbreeding coefficient in a pedigreed population

iii) Determining inbreeding coefficient when fullsib mating occurs for the first time and its recurrence relation

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Q2) Answer precisely by giving reasons wherever required (8 marks)

a) When selection is favoring heterozygotes, do loci respond to selection?

b) When selection is favoring heterozygotes, do loci respond to selection?

c) Is it sufficient if 50 F2 plants are raised in handling a diverse varietal cross? What is the remedy for getting the most desired transgressive segregants?

d) Is it sufficient if 50 BC1 plants are raised in diverse varietal cross with wild species parent for transferring disease resistance?

e) Show what will be inbreeding coefficient when cousin marriage occurs for the first time?

f) Show what will be inbreeding coefficient when niece marriage occurs for the first time?

g) Why inbreeding depression and the harmful effects thereof are observed only on inbreeding and not as long as population is subjected to panmixis?

h) How population of maize responds to selection for yield at different levels of dominance?

i) What are similarities in consequences of selfing and backcrossing?

j) What are differences in consequences of selfing and backcrossing?

k) Distinguish between consequences of restricted random mating on a subpopulation and the whole population?

l) What care is taken while maintaining a variety of maize and a breed of cattle and why?

m) Why artificial selection is proposed to be initiated in F6 in SSD method in F6 generation?

n) Why artificial selection is proposed to be initiated in F2 in Pedigree method?

o) Differences in constitution of F2 and F6 population?

p) What is the effect of linkage on proportion of homozygosity and homozygous individuals seen in segregating generations derived from a cross?

Q9) Give the meaning of following terms (4 marks)

a) Selection coefficient
b) Wahlund’s frequencies
c) Constancy of allelic frequency
d) Polygenic equilibrium
e) Recurrence relation
f) Coefficient of coancestry
g) Effective population size
h) Stable polymorphism