Question

Genes are segments of DNA that contain “instructions” for the expression of traits. The presence of just one dominant gene in a chromosome pair results in expression of a certain trait. A recessive gene, on the other hand, will only result in the expression of a trait if the gene appears in both paired chromosomes.


In guinea pigs, the gene for black coat color is the dominant gene, and the gene for white coat color is the recessive gene.


A guinea pig has a black coat. Which of these explanations could be POSSIBLE?


a. The guinea pig received a recessive gene for white coat color from one
parent and no gene for coat color from the other parent.

b. The guinea pig received a dominant gene for black coat color from one
parent and no gene for coat color from the other parent.

c. The guinea pig received a dominant gene for black coat color from one
parent and a recessive gene for white coat color from the other parent.

d. The guinea pig received a recessive gene for white coat color from one
parent and a recessive gene for white coat color from the other parent.

Answer 1

C. However, if the gene is sex-linked (on the X chromosome), a male offspring could get B.