Return to Blog
Homepage
PCAT Biological Processes – Color Blindness
- by
- Feb 19, 2018
- PCAT Question of the Day
Color blindness (B) is a recessive (b) sex-linked disorder that results from a mutation on the X chromosome. What would be the most likely phenotypes of the male and female progeny when a colorblind man and a woman with no family history of color blindness mate?
- All of the male and none of the female offspring will be colorblind
- Half of the male and half of the female offspring will be colorblind
- None of the male and none of the female offspring will be colorblind
- None of the male and all of the female offspring will be colorblind
Click for Explanation
This question asks the examinee to determine the offspring phenotypes that result from cross between a woman with normal vision and a colorblind man. To answer this question, the easiest method is requires the use of a Punnett square.
Since the woman has no family history of colorblindness, it is safe to assume that she is homozygous dominant (XBXB). The colorblind male on the other hand has the mutated allele (XbY).
According to the Punnett square above, none of the males and none of the females will be affected by this recessive disorder. Therefore, none of the male and none of the female offspring will be colorblind making C the correct answer.
Related Post
Search the Blog
Free Consultation
Interested in our Online MCAT Course, One-on-One MCAT Tutoring or Med admissions packages? Set up a free consultation with one of our experienced Senior Student Advisors.
Schedule NowPopular Posts
-
-
-
-
-
MCAT Blog How to Review MCAT Full-Lengths
Free MCAT Practice Account
Need great MCAT practice?Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.
Learn More
Submit a Comment