Question

Which of the following statements about autosomal recessive traits is true?
A. If neither parent expresses the trait, but the offspring does, both parents must be heterozygous for the trait.
B. If an individual expresses the trait, then all of his or her offspring will also express the trait.
C. If an individual expresses the trait, none of his or her offspring will express the trait.
D. Only females can pass the trait to their offspring.

Answer 1

Answer:

A. If neither parent expresses the trait, but the offspring does, both parents must be heterozygous for the trait.

Explanation:

If neither parents express the trait is because they are heterozygous and the dominant allele is being expressed over the recessive trait. When parents cross they have 25% of having an offspring that expresses the recessive trait, this means the offspring is a recessive homozygous. In the attached example 25% or 1/4 will have a short stem.