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TBR Bio Chapter 9 Passage V

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MedPR

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Red-green color blindness is a sex-linked recessive trait and is found in 8% of the male population and in less than 1% of the female population, even though about 15% of the female population are carriers. A defect in the synhesis of the green-sensitive pigment is referred to as the deutan type of color blindness. Approximately 6% of the 8% of all males who are color-blind have a deutan defect. The remaining 2% have a protan defect, a type of color blindness resulting from a defect in the synthesis of the red-sensitive pigment.

The percentage of woman who are heterozygous carriers of protan color blindness is about:

A. 2%
B. 4%
C. 8%
D. 11%
 

typicalindian

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:idea: ok so genetics is NOT my strong point so I'll try my best to explain how I got the answer.

Red-green color blindness is a sex-linked recessive trait and is found in 8% of the male population and in less than 1% of the female population, even though about 15% of the female population are carriers. A defect in the synhesis of the green-sensitive pigment is referred to as the deutan type of color blindness. Approximately 6% of the 8% of all males who are color-blind have a deutan defect. The remaining 2% have a protan defect, a type of color blindness resulting from a defect in the synthesis of the red-sensitive pigment.

EDIT: heres a more simple, less confusing explanation

8% of all males possess the defective trait on their X chromosome
15% of all females possess the defective trait on one of their X chromosomes

1/4 of all the males with the defective trait have the protan defect
-you get 1/4 by doing 2% / 8%

therefore 1/4 of all female carriers should also have the protan defect
1/4 of 15% is 3.75%, or 4% when rounded.
 
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