Question

Which of the following indicates a heterozygous individual? a. \(A B\) b. \(A A\) c. \(A a\) d. \(a a\)

Short answer

Option c. \(A a\) indicates a heterozygous individual, as it has one dominant allele (A) and one recessive allele (a) for the same gene.

Step-by-step solution

Understanding the term "heterozygous"

For an individual to be considered heterozygous for a certain gene, they must have two different alleles for that gene. In other words, the two gene copies (inherited from each parent) should be of different forms, one being dominant (capital letter, e.g. A) and the other recessive (lowercase letter, e.g. a).

Evaluating each option

We need to check each option to see if they represent a heterozygous individual: a. \(A B\) - This option has two different letters, not different forms of the same letter, so it doesn't represent a heterozygous individual. b. \(A A\) - In this option, both gene copies are the same (both are dominant), so this individual is homozygous dominant, not heterozygous. c. \(A a\) - This option has two different forms of the same letter (one dominant and one recessive), so it represents a heterozygous individual. d. \(a a\) - In this option, both gene copies are the same (both are recessive), so this individual is homozygous recessive, not heterozygous.

Choose the correct option

Based on our evaluation of each option, we can conclude that option c. \(A a\) represents a heterozygous individual, as it has one dominant allele (A) and one recessive allele (a) for the same gene.