Principles of Genetics and Breeding

Answers

1. Genotypes of the parents

a) Bb Dd x Bb Dd

b) BB DD x B- dd

c) Bb dd x bb DD

d) bb Dd x bb Dd

e) Bb dd x Bb dd

f) BB Dd x B- D-

g) Bb Dd x Bb dd

2. a) Phenotypic ratio

Normal spine grey 9: Normal spine gold 3: Curved spine grey 3 : Curved spine gold 1

Genotypic ratio :

SnSn GG (1) : SnSn Gg (2) : SnSc GG (2) : SnSc Gg (4) :

SnSc gg (2) : SnSn gg (1) : SnSn gg (1) : ScSc Gg (2) : ScSc GG (1) : ScSc gg (1)

b) Normal spine Grey : Curved spine grey ( 1:1 )

SnSc GG : SnSc Gg : ScSc GG : ScSc Gg

1 : 1 : 1 : 1

c) All normal spine gold, SnSn gg : SnSc gg (1:1)

d) All curved spine gold (ScSc gg)

3. F₁ All Grey-Green Normal fin Gg Nn

F₂ Grey Normal fin -9/16,

Grey long fin -3/16,

Pink normal -3/16,

pink long fin -1/16

4. a) All pearl Aa Bb

b) Normal-7/16, Pearl -9/16

c) Normal-3/4, Pearl -1/4

d) Pearl -3/4, Normal-1/4