Question

Given below are two statements: Statement (I): Interaction deviations exist when genotype refers to more than one locus. Statement (II): Epistasis describes how gene interactions can affect phenotypes. In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Remember that:
- Dominance is a single-locus phenomenon.
- Epistasis (Interaction deviation) is a multi-locus phenomenon.
Both describe non-additive genetic interactions.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Gene interactions can occur between alleles at the same locus (dominance) or between alleles at different loci.
Interactions between alleles at different loci are referred to as epistatic interactions or interaction deviations (\( I \)).

Step 2: Detailed Explanation:
Let us analyze both statements.
- Statement (I) describes the requirements for interaction deviations.
An interaction deviation (epistasis) refers to the interaction of genes at different loci.
If a genetic model only considers a single locus, there can be no interaction between loci.
Therefore, interaction deviations can only exist when the genotype refers to more than one locus.
Thus, Statement (I) is correct.
- Statement (II) defines epistasis.
Epistasis is the biological phenomenon where the phenotypic expression of a gene at one locus is altered, masked, or enhanced by a gene at another locus.
This interaction directly affects the resulting phenotype.
Thus, Statement (II) is correct.
Therefore, both Statement (I) and Statement (II) are correct.

Step 3: Final Answer:
Both Statement (I) and Statement (II) are correct, corresponding to option 1.