Question

examine this pedigree showing the inheritance of an autosomal trait. individuals with the recessive phenotype are shaded darker than those with the dominant phenotype. if this trait is represented by the letter r, what is the genotype of individual b? rr rr rr rr or rr

Explanation:

Step1: Understand dominant and recessive traits

In genetics, a recessive phenotype is shown when an individual has two recessive alleles. A dominant phenotype can be shown with either two dominant alleles (RR) or one dominant and one recessive allele (Rr). Since shaded individuals have the recessive phenotype (rr), and individual B has the dominant phenotype. But as it is an autosomal trait, and assuming no other information (like cross - results which are not given here in detail about B's parents in a way that would suggest heterozygosity), and in the absence of evidence for heterozygosity (no offspring data for B that would require a recessive allele), the most likely genotype for a dominant - phenotype individual (when not forced to be heterozygous by offspring data) is RR.

Answer:

RR