Question

Q:- Short hair rabbit is goverened by a dominant gene (L)

andlong hair by its recessive alleles (l). Black hair results from
theaction of the dominant genotype (B) and brown from therecessive
genotype (b).
A. In cross between dihybrid short ,black and homozygousshort,
brown rabbits, what genotypic and phenotypic ratios areexpected
among their progeny?
B. Determine the expected genotypic and phenotypic ratios
inprogeny from cross LlBb*Llbb.

Answer 1

A) he phenotypic ratio is

short & black : short & brown

8:8

1:1

Genotypic Ratio is

LLBb : LLbb: LlBb : Llbb

4:4:4:4

1:1:1:1

B)

Genotypic Ration

LLBb : LLbb: LlBb: Llbb: llBb: llbb

2: 2: 4: 4: 2:2

1:1:2:2:1:1

Phenotypic ratio

Short & Black : Short & brown: Long & black : Long & brown

6: 6: 2: 2

3:3:1:1

Step-by-step explanation:

Given -

Allele for short hair (L) is dominant over long hair allele (l)

And Black hair allele (B) is dominant over brown hair allele (b)

A) Genotype for dihybrid short and black rabbit is LlBb

Genotype for homozygous short and brown rabbits is LLbb

Cross between LlBb and LLbb will result into following offspring

LB Lb lB lb

Lb LLBb LLbb LlBb Llbb

Lb LLBb LLbb LlBb Llbb

Lb LLBb LLbb LlBb Llbb

Lb LLBb LLbb LlBb Llbb

Hence, the phenotypic ratio is

short & black : short & brown

8:8

1:1

Genotypic Ratio is

LLBb : LLbb: LlBb : Llbb

4:4:4:4

1:1:1:1

B) LlBb*Llbb.

LB Lb lB lb

Lb LLBb LLbb LlBb Llbb

Lb LLBb LLbb LlBb Llbb

lb LlBb Llbb llBb llbb

lb LlBb Llbb llBb llbb

Genotypic Ration

LLBb : LLbb: LlBb: Llbb: llBb: llbb

2: 2: 4: 4: 2:2

1:1:2:2:1:1

Phenotypic ratio

Short & Black : Short & brown: Long & black : Long & brown

6: 6: 2: 2

3:3:1:1