Biology Inheritance / Variation & Genetics SZABMU 2024
PMDC Verified Question 5 of 94
In fruit fly Drosophila, the heterozygote (w+/w) has more quantity of fluorescent pigments in eyes than wild (w+/w+) or white eye (w/w) homozygote. This is an example of:
A
Over dominance
B
Complete dominance
C
Codominance
D
Partial dominance
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Over dominance
Concept:

Sometimes, carrying two different alleles produces a biological advantage or an exaggerated phenotype compared to carrying two identical alleles.

Solution:

  • When a heterozygote exhibits a phenotype that is more extreme, superior, or quantitatively greater than that of either homozygous parent, it is called over-dominance.
  • In this specific example, the heterozygous fly (\(w^+/w\)) produces a significantly higher quantity of fluorescent eye pigments than even the homozygous dominant wild type (\(w^+/w^+\)).


Why other options are incorrect:

  • Complete dominance: The heterozygote would perfectly match the dominant homozygote.
  • Codominance / Partial dominance: The heterozygote would show an intermediate or blended phenotype, not one that exceeds both parents.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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