Biology Inheritance / Variation & Genetics NUMS 2024
PMDC Verified Question 3 of 94
What will be the probability of purple and terminal flower in pea plant in \(F_2\) generation if we cross true breeding purple axial flower plant with white terminal flower plant?
A
1/16
B
3/16
C
9/16
D
1/2
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: 3/16
Concept:

In a standard Mendelian dihybrid cross, the \(F_2\) phenotypic ratio is 9:3:3:1 based on the assortment of two dominant/recessive traits.

Solution:

  • Purple color (P) is dominant over White (p). Axial position (A) is dominant over Terminal (a).
  • Parents: True-breeding Purple/Axial (PPAA) x White/Terminal (ppaa).
  • \(F_1\) generation: All are heterozygous Purple/Axial (PpAa).
  • \(F_2\) generation (selfing PpAa x PpAa):
  • The ratio is 9 (Dom/Dom) : 3 (Dom/Rec) : 3 (Rec/Dom) : 1 (Rec/Rec).
  • The phenotype "Purple and terminal" requires one dominant trait (Purple) and one recessive trait (terminal).
  • Therefore, its probability is exactly 3/16.


Why other options are incorrect:

  • 9/16: Purple and Axial (Both Dominant).
  • 1/16: White and Terminal (Both Recessive).

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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