Bio QBook; q121

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khadeja
Posts: 85
Joined: Wed Feb 07, 2018 10:42 am

Bio QBook; q121

Post by khadeja » Fri Apr 13, 2018 8:08 pm

The father can be either homozygous dominant or heterozygous right?
wouldn't those 2 need to be added?
NS_Tutor_Andrew
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Re: Bio QBook; q121

Post by NS_Tutor_Andrew » Sat Apr 14, 2018 7:40 pm

Hi khadeja,

Yes, I think you're technically right. Noting the discrepancy between the calculated result of 1/48 and the correct answer choice of 1/50, I'm inclined to think that the question chose to neglect that possibility because it should only affect the overall outcome very slightly, and the answer choices are far enough apart from each other that some degree of crude estimation might be time-saving. However, if so, that could be explained more clearly. I'm also hesitant to endorse that strategy for Mendelian genetics problems, because the MCAT tends to set them up with numerically relatively close answers that correspond to different ways of setting up the problem, meaning that conceptual clarity should generally be prioritized over a "close enough" kind of analysis. I'll make a note of this for the next edition of the QBook -- thanks for asking!
Andrew D.
Content Manager, Next Step Test Prep.
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