Biology Inheritance / Variation & Genetics MDCAT 2017
PMDC Verified Question 85 of 94
Self-fertilization of \(F_1\) dihybrids, following independent assortment of alleles will result in:
A
3/16 tall, round; 3/16 dwarf, wrinkled
B
9/16 tall, round; 1/16 dwarf, round
C
9/16 tall, wrinkled; 3/16 dwarf, round
D
3/16 tall, wrinkled; 3/16 dwarf, round
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: 3/16 tall, wrinkled; 3/16 dwarf, round
Concept:

In a standard Mendelian dihybrid cross involving two traits showing complete dominance, the phenotypic ratio in the \(F_2\) generation is \(9:3:3:1\).

Solution:

  • A dihybrid cross (e.g., Tall/Round x Dwarf/Wrinkled) yields an \(F_1\) generation of all Tall, Round heterozygotes.
  • Selfing the \(F_1\) produces the following probabilities:
  • 9/16 Tall, Round (Dominant/Dominant)
  • 3/16 Tall, Wrinkled (Dominant/Recessive)
  • 3/16 Dwarf, Round (Recessive/Dominant)
  • 1/16 Dwarf, Wrinkled (Recessive/Recessive)
  • Option D perfectly isolates the two recombinant phenotypes: 3/16 tall, wrinkled; 3/16 dwarf, round.


Why other options are incorrect:

  • Option A incorrectly lists the double recessive as 3/16 instead of 1/16.
  • Option B incorrectly mixes the dominant fraction with an incorrect recessive fraction.

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