Question

In the pedigree below, individual 4 in generation ii (two) would have to have which of the following genotypes, if the shaded (black) shape indicates a recessive trait?

1) There is not enough information
2) aa
3) aa
4) aa

Answer 1

Individual 4 in generation II must have the genotype aa in order to express the recessive trait indicated by the shaded shape in the pedigree.

Step-by-step explanation:

In the context of the pedigree provided, if the shaded shape indicates a recessive trait, then individual 4 in generation II would have to be homozygous recessive, with the genotype aa. This is because in the case of simple recessive traits, the trait itself is expressed when an individual has two copies of the recessive allele.In the given pedigree, individual 4 in generation ii would have the genotype aa if the shaded shape indicates a recessive trait. This is because the shaded shape represents individuals with the recessive trait, and as a recessive trait, it requires two copies of the recessive allele to be expressed. Therefore, individual 4 must have the genotype aa.

Given the information that individuals 1 and 3 have the genotype AA, and individual 2 has the genotype aa, we can infer that individual 4 must also have the genotype aa to exhibit the recessive phenotype (shaded). Recessive genetic disorders like Alkaptonuria, which is mentioned as an example, require two copies of the recessive allele for the trait to be expressed.