Which of the following best describes a dihybrid cross involving two genes that interact epistatically?

• A. A cross between individuals homozygous for two genes, resulting in independent assortment
• B. A cross involving a single gene with two alleles showing incomplete dominance
• C. A cross between individuals heterozygous for two genes, where one gene masks the expression of the other
• D. A cross between two individuals with identical genotypes for both genes

Answer: (C)

Verified step by step guidance

1. Understand what a dihybrid cross is: it involves two genes, each with two alleles, and typically examines how these genes assort and interact in offspring.
2. Recall the concept of epistasis: this occurs when the expression of one gene masks or modifies the expression of another gene at a different locus.
3. Identify the genotypes involved in a dihybrid cross with epistasis: usually, both parents are heterozygous for both genes (e.g., AaBb x AaBb), allowing observation of gene interactions in the progeny.
4. Recognize that independent assortment refers to genes segregating without influencing each other, which is not the case in epistasis where one gene affects the expression of the other.
5. Conclude that the best description of a dihybrid cross involving epistasis is a cross between individuals heterozygous for two genes, where one gene masks the expression of the other.