Week 7 - sample lab exam question

WEEK 7 - SAMPLE LAB EXAM QUESTION

QUESTION:

Color blindness in humans is a sex-linked, recessive trait. A man with normal color vision, whose father was color-blind, marries a woman with normal color vision, whose father was also color-blind.
1. List the alleles. What are the genotypes of the man and the woman?
2. What are the chances that the first child from marriage will be a color-blind boy? Show how you derived your answer.
ANSWER:
1. X^C - normal color vision
  
  X^c - color-blindness
  
  Man - X^CY
  
  Woman - X^CX^c
2. 25%

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