Question

A phenotypic ratio of \(12:3:1\) is produced due to

• A. Recessive epistasis
• B. Dominant epistasis
• C. Duplicate recessive epistasis
• D. Complementation

Hint:

Important modified Mendelian ratios: \[ \boxed{ \begin{aligned} 12:3:1 &\rightarrow \text{Dominant epistasis} 9:3:4 &\rightarrow \text{Recessive epistasis} 9:7 &\rightarrow \text{Complementary genes} 15:1 &\rightarrow \text{Duplicate dominant genes} \end{aligned} } \]

Answer 1

The Correct Option is B

Step 1: Recall common modified dihybrid ratios. Different gene interactions produce characteristic phenotypic ratios: \[ \begin{aligned} 12:3:1 &\rightarrow \text{Dominant epistasis}, 9:3:4 &\rightarrow \text{Recessive epistasis}, 9:7 &\rightarrow \text{Complementary genes}, 15:1 &\rightarrow \text{Duplicate dominant genes}. \end{aligned} \]

Step 2: Identify the correct interaction. Since the observed phenotypic ratio is \[ 12:3:1, \] it corresponds to \[ \boxed{\text{Dominant epistasis}.} \] Therefore, \[ \boxed{(B)} \] is the correct answer.