Biology Inheritance / Variation & Genetics DUHS 2022
PMDC Verified Question 56 of 94
Phenotypic ratio of single trait inheritance:
A
1:2:1
B
3:1
C
1:2
D
1:3:2
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: 3:1
Concept:

A monohybrid cross involves true-breeding parents differing in only a single trait.

Solution:

  • When two heterozygotes (e.g., Tt x Tt) from the \(F_1\) generation of a single trait inheritance are crossed, they segregate their alleles.
  • The resulting phenotypic ratio in the \(F_2\) generation between dominant and recessive plants is 3:1 (75% showing the dominant trait, 25% showing the recessive trait).


Why other options are incorrect:

  • 1:2:1 represents the genotypic ratio of a monohybrid cross (1 TT : 2 Tt : 1 tt), or the phenotypic ratio in cases of incomplete dominance/co-dominance.

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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