Biology Inheritance / Variation & Genetics MDCAT 2017
PMDC Verified Question 86 of 94
As a result of cross-fertilization of true breeding pea plant having purple-colored flowers with that of white colored flowers, the offspring will have flower with:
A
1/4 purple and 3/4 white
B
All white
C
1/4 white and 3/4 purple
D
All purple
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: All purple
Concept:

The Law of Dominance states that in a heterozygote, the dominant allele will completely mask the presence of the recessive allele.

Solution:

  • A true-breeding purple plant has the genotype PP.
  • A true-breeding white plant has the genotype pp.
  • Purple color is entirely dominant over white color.
  • Crossing PP x pp results in an \(F_1\) generation where 100% of the offspring have the heterozygous genotype Pp.
  • Since P is dominant, all offspring will have purple flowers.


Why other options are incorrect:

  • Fractions like 3/4 and 1/4 only appear in the \(F_2\) generation resulting from the cross of two heterozygotes (Pp x Pp).

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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