Biology Inheritance / Variation & Genetics MDCAT 2016
PMDC Verified Question 89 of 94
A character determined by three alleles is:
A
Human skin color
B
Human eye color
C
Human blood group
D
Human Rh factor
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Human blood group
Concept:

When a specific gene locus has more than two naturally occurring variants in a population, it exhibits multiple allelism.

Solution:

  • The Human ABO blood group is encoded by a single polymorphic gene (Gene I) on chromosome 9.
  • It is uniquely determined by three alleles: \(I^A\), \(I^B\), and \(i\).


Why other options are incorrect:

  • Skin and Eye color: These are polygenic traits, meaning they are controlled by multiple different genes (each with their own alleles) interacting additively, not three alleles at a single locus.
  • Rh factor: Primarily determined by the presence (D) or absence (d) of a single antigen, generally behaving as a two-allele system.

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.

Previous Question All Inheritance / Variation & Genetics MCQs Next Question

Want to solve full-length papers under timed exam conditions?

Practice with zero-scroll lockdown sprints, dynamic latency zone timers, live peer selection telemetry, and the automated Amber mistake recovery loop.

Enter Arena Sprint iOS App Android App