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.

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

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

LbLLBbLLbbLlBbLlbb

LbLLBbLLbbLlBbLlbb

LbLLBbLLbbLlBbLlbb

LbLLBbLLbbLlBbLlbb

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

LbLLBbLLbbLlBbLlbb

LbLLBbLLbbLlBb  Llbb

lbLlBbLlbb         llBb         llbb

lbLlBbLlbb         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

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)