Question

Hair texture in humans is an example of incomplete dominance. If a man with curly hair has children with a woman with straight hair, all the children has an intermediate texture that is wavy hair. What is the likely proportion of phenotypes in their children?

Answer 1

Answer:

100% wavy haired

Explanation:

Let the allele for curly hair texture be represented by C and the allele for for straight hair texture be c.

A man with curly hair will have the genotype CC.

A woman with straight hair will have the genotype cc.

Crossing the two in marriage:

CC   x   cc

Progeny: Cc, Cc, Cc and Cc.

Recall that the hair texture gene exhibit incomplete dominance, meaning that heterozygous individuals have intermediate attribute - wavy hair.

Hence, all the children will have wavy hair.

Answer 2

Answer:

100% Wavy hair

Explanation:

The gene involved here codes for hair texture in humans. The alleles of the gene (straight, S and curly, s) exhibits incomplete dominance. Incomplete dominance is a genetic scenario whereby one allele does not completely mask the expression of the other allele, instead an intermediate phenotype that is heterozygous is formed.

In this case, a man with curly hair (ss) marries a woman with straight hair (SS). The children from this cross will all possess a heterozygous genotype (Ss) and be phenotypically wavy-haired, since Incomplete dominance is exhibited by the gene. Therefore, 100% of the offsprings/children will have wavy hair phenotype.