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Question #46142
The Question
In Ascaris lumbricoides, sexual dimorphism is distinctly observed where females are longer than males. Suppose a novel environmental pressure in the host intestine selectively favors only the exceptionally longest females due to their higher fecundity, gradually shifting the mean body length of the female population over generations. Which of the following statements is INCORRECT regarding this evolutionary event?
Options
- A.
This is an example of directional selection, conceptually similar to the shift observed in Biston betularia during industrialization.
- B.
The selection pressure acts on a pre-existing sexually dimorphic trait within a dioecious population.
- C.
The peak of the phenotypic distribution curve for female body length will get higher and narrower at the original mean.
- D.
This evolutionary strategy enhances fitness through gametic specialization and increased reproductive output under environmental stress.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Aschelminthes Sex Differentiation|Natural Selection Directionality|Industrial Melanism
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The question integrates Animal Kingdom (Aschelminthes sexual dimorphism) with Evolution (Types of Natural Selection).
The trap relies on students failing to map the graphical changes of natural selection to a novel scenario.
Option C uses the exact NCERT phrasing for stabilizing selection ('peak gets higher and narrower') to trap students who do not visualize the graph shifting directionally.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Animal Kingdom - Class 11 |
| Concept | Aschelminthes Sex Differentiation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |