Question

In Mirabilis jalapa, red flowered homozygous plant crossed with white flower homozygous plant. The phenotypic ratio in F2 is 1:2:1 instead of 3:1, due to which phenomena?

• A. Complete dominance
• B. Incomplete dominance
• C. Co-dominance
• D. Over-dominance

Hint:

Remember that incomplete dominance results in offspring showing a blend of parental phenotypes.

Answer 1

The Correct Option is B

Step 1: Concept
Genetic inheritance patterns

Step 2: Meaning
Understanding different modes of gene expression in offspring resulting from various genetic interactions between parents.

Step 3: Analysis
The question pertains to the explanation behind a deviation from the expected 3:1 phenotypic ratio (which would be seen under simple Mendelian dominance) observed in F2 generation. The correct answer indicates this is due to incomplete dominance, where neither allele for flower color completely masks the other during trait expression.

Step 4: Conclusion
The observed 1:2:1 phenotypic ratio suggests that red and white are incompletely dominant over each other in Mirabilis jalapa plants, resulting in a third phenotype in F2 generation due to blending of traits from both parents. Final Answer: (B)