Question

if brown fur (b) is dominant to white fur (b) in rats, what percentage of offspring from a bb x bb cross are expected to have brown fur?

Explanation:

Step1: Set up Punnett square

	B	b
b	Bb	bb

Step2: Count brown-fur genotypes

Brown fur is expressed by BB, Bb, Bb. Total genotypes: 4.
Expression: $\frac{3}{4} \times 100\% = 75\%$

Answer:

75%