Question

If the pedigree is for an autosomal recessive characteristic, which individuals are definitely heterozygous?

a. I-1, I-2, II-2, II-4, and II-5
b. I-1, I-2, I-4, III-1
c. I-1, I-2, II-4, II-5, III-1
d. II-2, II-4, II-5, II-3
e. II-2, II-4, II-5, III-1

Answer 1

c. I-1, I-2, II-4, II-5, III-1. Individuals who are definitely heterozygous for an autosomal recessive characteristic are I-1, I-2, II-4, II-5, and III-1 in the given pedigree.

Step-by-step explanation:

In an autosomal recessive inheritance pattern, individuals are only affected if they have two copies of the recessive allele. Heterozygous individuals are carriers of the recessive allele but do not show the trait. Looking at the pedigree, the individuals who are definitely heterozygous for the autosomal recessive characteristic are I-1, I-2, II-4, II-5, and III-1. These individuals have the possibility of passing on the recessive allele to their offspring, even though they do not show the trait themselves.