Hiding My Stomach With Clothes

Exercises on the Laws of Mendel

Read, solve and post your solutions as comments (exercises taken from our textbook LS). Next week the solutions.

EXERCISE 1

It happened to a British couple in Nottingham (England) in 2006. For two parents, both in color, were born of twins different color, one white and one black girl. But how is this possible? Considering that skin color is determined by a pair of genes (alleles), a dominant, N, one dark and one recessive B, the light, determines the genotype of each parent and that of twins. It also explains how it was possible that a pair of parents of color may be born twins of different colors, one white and one black. In particular, answer the following questions giving reasons for your answers.

a. is possible that both parents were homozygous NN?

b. You BB was one of the two homozygous and one heterozygous NB?

c. is possible that both were heterozygous NB?

d. The black girl is homozygous or heterozygous?

e. The white child is homozygous or heterozygous?

EXERCISE 2

The sickle cell anemia is an inherited disorder caused by a recessive gene. A indicates the healthy gene to the dominant and recessive gene responsible for the disease. Write the genotype of an individual suffering from this disease, a healthy individual and a carrier.

Calculate the percentage probability that a sick person born in the following cases:

a. both parents are both carriers;

b. one parent carries the other is healthy.