Question

In human, dark hair color,D is dominant over light hair color,d.If the egg cell of a blonde female who carries only genes for light color ed hair,dd ,is fertilized bythe sperm cell of a male who carries only the genes for dark hair,DD, what are the chances that offspring will have light -colored hair?

Answer 1

When a blonde female with genotype dd and a dark-haired male with genotype DD have offspring, all their children will have dark hair, as the dominant dark hair allele D will mask the recessive light hair allele d.

Step-by-step explanation:

The question asks about the inheritance of hair color in humans, which involves understanding dominant and recessive alleles. Since the female is homozygous for light hair color (dd), and the male is homozygous for dark hair color (DD), their offspring can only have one of each allele (Dd), resulting in a phenotype of dark hair. This is because the dominant allele for dark hair (D) will mask the presence of the recessive allele for light hair (d).

Using a Punnett Square to predict the genetic outcome of such a cross would show that all the offspring (F1 generation) will carry the genotype Dd, and thus, all will display the dominant dark hair trait—zero percent chance for offspring to have light-colored hair. This is a clear example of a monohybrid cross where one characteristic is being studied, and Mendel's laws of inheritance apply.