Question

a certain species of rabbit can have either black or grey fur. the allele for black fur is dominant over the allele for grey fur. if a homozygous black rabbit is crossed with a heterozygous black rabbit, what phenotypic ratio will occur in the first generation?
a. 25% black : 75% grey
b. 50% black : 50% grey
c. 75% black : 25% grey
d. 100% black : 0% grey

Explanation:

Step1: Define alleles

Let \( B \) be dominant (black), \( b \) be recessive (grey). Homozygous black: \( BB \), heterozygous black: \( Bb \).

Step2: Set up Punnett square

	\( B \)	\( B \)
\( b \)	\( Bb \)	\( Bb \)

Step3: Determine phenotypes

\( BB \) and \( Bb \) both show black fur. All 4 offspring (2 \( BB \), 2 \( Bb \)) have black fur. So phenotypic ratio is 100% black : 0% grey.

Answer:

D. 100% black : 0% grey