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Question #45810
The Question
In Pisum sativum, the gene controlling starch synthesis has two alleles (B and b). Homozygotes (BB) produce large starch grains and round seeds, while homozygotes (bb) produce small starch grains and wrinkled seeds. Regarding the F1 heterozygote (Bb) and the nature of this gene, which of the following statements is INCORRECT?
Options
- A.
The F1 heterozygote produces round seeds, indicating that allele B is completely dominant over allele b for the morphological phenotype.
- B.
The F1 heterozygote produces intermediate-sized starch grains, demonstrating incomplete dominance for the biochemical phenotype.
- C.
The dominance of allele B is an autonomous feature of the gene, as it consistently dictates the primary metabolic pathway regardless of the chosen phenotype.
- D.
This gene exemplifies pleiotropy, where a single gene product influences multiple phenotypic traits due to underlying metabolic linkages.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Starch_Branching_Enzyme|Seed_Coat_Morphology|Incomplete_Dominance
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that 'B is dominant over b' without realizing that dominance is phenotype-dependent.
The trap lies in assuming dominance is an inherent, autonomous property of the DNA sequence or the enzyme itself, whereas NCERT highlights that dominance is relative to the specific trait being measured (morphological vs. biochemical).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Principles of Inheritance and Variation - Class 12 |
| Concept | Pleiotropy Logic |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |