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Question #45813
The Question
Which of the following statements regarding the evolutionary and genetic dynamics of the sickle cell allele () is INCORRECT?
Options
- A.
The allele demonstrates pleiotropy by altering erythrocyte morphology under hypoxia while simultaneously disrupting the life cycle of Plasmodium falciparum.
- B.
In malaria-endemic regions, balancing selection operates to maximize population fitness by eventually fixing the allele at 100% frequency.
- C.
The persistence of the allele despite its lethality in the homozygous state represents an evolutionary trade-off that imposes a segregational genetic load.
- D.
If a malaria-endemic population migrates to a malaria-free environment, directional selection will gradually decrease the frequency of the allele.
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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
Heterozygote_Advantage|Evolutionary_Fitness|Malaria_Resistance
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse 'selection for an allele' with 'fixation of an allele'.
While the allele is selected FOR in malaria zones via heterozygote advantage, the very nature of balancing selection prevents it from reaching 100% frequency (fixation), as homozygous recessive individuals are continuously removed from the gene pool.
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 |