In guinea pigs, fur color depends on one pair of genes. Black fur is dominant to white fur. A purebred guinea pig with black fur is crossed with a purebred guinea pig with white fur. Assume no mutations occur.
What is the probability of each fur color in the offspring?
Answer options with 4 options
A.
no black fur, all white fur
B.
one-half black fur, one-half white fur
C.
three-fourths black fur, one-fourth white fur
D.
all black fur, no white fur
B. one-half black fur, one-half white fur
Explanation: In this cross, the black fur allele (B) is dominant to the white fur allele (b). The black fur guinea pig is homozygous dominant (BB) and the white fur guinea pig is homozygous recessive (bb).
When these two purebred guinea pigs are crossed, all of the offspring will inherit one black fur allele from the black fur parent and one white fur allele from the white fur parent (Bb). Therefore, all of the offspring will have black fur.
However, all of the offspring will be carriers of the white fur allele (Bb). If these carriers are crossed with each other, the Punnett square would show that 25% of the offspring would be white fur (bb) and 75% would be black fur (Bb). This means there is a 50% chance of black fur and a 50% chance of white fur in the offspring.