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Question #45342
The Question
In a population of a grass species, seed weight is a polygenic trait controlled by three unlinked gene pairs, typically exhibiting a classic Gaussian (bell-shaped) distribution curve. A specific maternal plant, which is highly heterozygous for these polygenes, undergoes facultative apomixis. Which of the following best describes the phenotypic distribution of seed weight in its immediate progeny?
Options
- A.
A single, extremely narrow peak because apomixis eliminates all genetic variance and produces pure lines.
- B.
A bimodal distribution or a sharp spike superimposed on a broader bell curve due to the mixture of clonal and recombinant seeds.
- C.
A standard Gaussian curve with a shifted mean, as apomixis induces genetic code degeneracy to maintain seed viability.
- D.
A flattened, uniform distribution curve because facultative apomixis restores complete homozygosity in the offspring.
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
Apospory|Quantitative_Inheritance|Maternal_Effect
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating Population Genetics (Polygenic curves) with Reproductive Strategies (Facultative Apomixis).
The primary trap is the misconception that asexual reproduction (apomixis) creates homozygous pure lines (Option D).
In reality, apomixis perfectly preserves the maternal genotype, including heterozygosity, which is why it is commercially valuable for maintaining hybrid vigor (a key NCERT concept).
Furthermore, missing the word 'facultative' leads students to incorrectly choose Option A.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Sexual Reproduction in Flowering Plants - Class 12 |
| Concept | Apomixis Genetics |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |