Freckles dominate in humans. In the family, both parents have freckles, but their daughter does not. How many gamete types does a man have?
Let us designate the gene that causes the development of freckles in humans as B, and the gene that, in a homozygous state, leads to their absence, as in.
The daughter does not have freckles, therefore, she is, because homozygosity for the phenotypic realization of this trait is a necessary condition.
Such a genotype is formed by the fusion of an egg cell and a sperm cell. Consequently, both parents must carry the gene for the recessive trait in their genotypes. Since both parents have freckles – they are heterozygous – BB. Such parents produce two types of germ cells – b and B.
Answer: There are 2 types of gametes.
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