Biology Inheritance / Variation & Genetics MDCAT 2017
PMDC Verified Question 87 of 94
The gene for red-green color blindness is present on:
A
Y-chromosome
B
Autosome No. 7
C
X-chromosome
D
Autosome No.9
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: X-chromosome
Concept:

Human color vision relies on opsin proteins, and the genes encoding these proteins are distributed across different chromosomes.

Solution:

  • Red-green color blindness is an X-linked recessive trait.
  • The genes encoding the red and green opsins are situated exclusively on the X chromosome.
  • Mutations in these specific X-chromosome genes lead to the inability to distinguish between red and green hues.


Why other options are incorrect:

  • Autosome No. 7: This is where the gene for blue opsin (tritanopia) is located, making blue color blindness an autosomal trait.

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