Question

Epistasis refers to

• A. No variation resulting from the interaction of alleles at different loci
• B. Variation resulting from the interaction of alleles at same loci
• C. No variation resulting from the interaction of alleles at different chromosomes
• D. Variation resulting from the interaction of alleles at different loci

Hint:

• Epistasis A gene at one locus alters the phenotypic expression of a gene at a second locus.
• It's an interaction between non-allelic genes.
• This can lead to modified Mendelian dihybrid ratios (e.g., 9:3:4, 9:7, 12:3:1 instead of 9:3:3:1).
• Example: Coat color in Labrador retrievers, comb shape in chickens.

Answer 1

The Correct Option is D

Epistasis is a phenomenon in genetics where the effect of one gene is modified or masked by one or several other genes. It is a form of genetic interaction, and it plays a vital role in the expression of phenotypic traits.

To clarify the options and provide the correct understanding:

Concept	Explanation
Epistasis	Variation resulting from the interaction of alleles at different loci
Alleles at same loci	This interaction typically results in additive effects or dominance, but not epistasis
Alleles on different chromosomes	While they may interact, epistasis specifically refers to loci, not entire chromosomes

The correct answer is: Variation resulting from the interaction of alleles at different loci. This highlights how genes at one locus can mask or alter the expression of genes at another locus, impacting the phenotype observed.