Question

In rabbits, black skin (B) is dominant over brown skin (b) and short hair (S) is dominant over long hair (s). If a homozygous black skin, short-haired male is crossed with a homozygous brown skin, long-haired female, all $F_1$ offspring are heterozygous black and short-haired. What would be the percentage of the homozygous black skin, short-haired offspring, if a male and female of $F_1$generation are made to breed?

• A. 6.25%
• B. 12.5%
• C. 18.75%
• D. 50%

Answer 1

The correct option is A 6.25%

F1: BbSs × BbSs

Gametes: BS, Bs, bS, bs

Punnett square:

Phenotypes:
Black skin and Short hair - 9
Brown skin and Short hair - 3
Black skin and Long hair - 3
Brown skin and Long hair - 1

(Homozygous black skin short hair $÷$ Total number of offspring) $\times$ 100
⇒ (1 ∕ 16) × 100 = 6.25%