Albinism in humans is inherited as a simple recessive trait. Determine the genotypes of the parents and offspring for the following families. When two alternative genotypes are possible, list both. (a) Two nonalbino (normal) parents have five children, four normal and one albino. (b) A normal male and a albino female have six childern, all normal.

To determine the genotypes of the parents and offspring, we need to understand the inheritance pattern of albinism in humans. Albinism is inherited as a simple recessive trait, which means that an individual needs to inherit two copies of the albino allele (aa) to express the albino phenotype.

Let's analyze each family scenario separately:

(a) Two nonalbino parents have five children, four normal and one albino.
In this case, the parents are both nonalbino (normal), which means they have at least one copy of the dominant allele (A). Since they have one albino child, it means both parents are carriers of the albino allele (Aa). Therefore, the genotypes of the parents can be represented as follows:

Father: Aa
Mother: Aa

For the offspring:
Each child has a 25% chance of inheriting two albino alleles (aa) and being albino, and a 75% chance of inheriting at least one dominant allele (A) and being normal. Therefore, the genotypes of the offspring can be as follows:

Child 1: Aa (normal)
Child 2: Aa (normal)
Child 3: Aa (normal)
Child 4: Aa (normal)
Child 5: aa (albino)

(b) A normal male and an albino female have six children, all normal.
In this case, the male is normal, so he has at least one dominant allele (A). The female is albino, which means she has two albino alleles (aa). Since all the children are normal, they must have inherited at least one dominant allele (A) from either parent. Therefore, the genotypes of the parents can be represented as follows:

Father: Aa (normal)
Mother: aa (albino)

For the offspring:
Each child has a 50% chance of inheriting the dominant allele (A) from the father and a 50% chance of inheriting it from the mother. Therefore, all the children will have the genotype Aa (normal).

In summary:
(a) Genotypes:
Father: Aa
Mother: Aa
Offspring: Aa, Aa, Aa, Aa, aa

(b) Genotypes:
Father: Aa
Mother: aa
Offspring: Aa, Aa, Aa, Aa, Aa, Aa