6 In humans having a widows peak W is dominant to not having

6. In humans, having a widow’s peak (W) is dominant to not having a widow’s peak (w). Sally has a widow’s peak. If Sally has a son who does not have a widow’s peak, what genotype can the father NOT be?

7. The ability to roll the tongue inward in humans is determined by the dominant gene T. From a couple both able to roll the tongue, a child is born. The child is unable to roll the tongue. What is the genotype of each of the parents?

8. Hemophilia is a X-linked recessive disorder due to the recessive gene h. If a hemophilic male (X^hY) mates with a heterozygous female (XX^h), what percentage of their sons will be hemophilic? What percentage of their daughters will be hemophilic?

Solution

6. In humans, having a widow’s peak (W) is dominant to not having a widow’s peak (w). Sally has a widow’s peak. If Sally has a son who does not have a widow’s peak, what genotype can the father NOT be?

Ans: The father of sally is not Ww or ww genotypic but may be WW.

7. The ability to roll the tongue inward in humans is determined by the dominant gene T. From a couple both able to roll the tongue, a child is born. The child is unable to roll the tongue. What is the genotype of each of the parents?

Ans: The genotype of each parent could be Ww (Father) and mother (Ww).

8. Hemophilia is a X-linked recessive disorder due to the recessive gene h. If a hemophilic male (X^hY) mates with a heterozygous female (XX^h), what percentage of their sons will be hemophilic? What percentage of their daughters will be hemophilic?

Ans: The percentage of getting hemophilia for sons and daughters is 25 %