Question

In humans, hitchhiker's thumb is the dominant trait (H). People who do not have hitchhiker's thumb have two recessive alleles (h). If you cross a purebred dominant male with a female without hitchhiker's thumb, what are the genotypes of each parent?

a. Male: HH, Female: Hh
b. Male: Hh, Female: hh
c. Male: HH, Female: hh

Answer 1

The genotypes of a purebred dominant male with hitchhiker's thumb and a female without it are HH and hh, respectively. All offspring will be heterozygous (Hh), exhibiting the hitchhiker's thumb.

Step-by-step explanation:

When crossing a purebred dominant male for hitchhiker's thumb with a female without the trait, we consider the genetic principles established by Gregor Mendel's inheritance theory. According to Mendel, a dominant allele will be expressed if present, while a recessive trait is only observed when an individual carries two recessive alleles. The purebred dominant male would have two dominant alleles (HH), while the female without a hitchhiker's thumb, having a recessive trait, would be hh in genotype.

The genotypes for each parent in this cross would be: Male: HH, Female: hh. All offspring will receive one dominant allele from the father and one recessive allele from the mother. Hence, they will all carry the genotype for the dominant trait (Hh), which will result in them exhibiting hitchhiker's thumb, because they all carry at least one dominant allele.