NS FL2 B/B Q5

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Amber9
Posts: 22
Joined: Thu Jul 04, 2019 11:08 am

NS FL2 B/B Q5

Post by Amber9 » Sun Jul 14, 2019 2:43 pm

Hi,

I understand that there are 6 possible outcomes, but why are only 3 viable gametes?

Thanks!
NS_Tutor_Mathias
Posts: 231
Joined: Sat Mar 30, 2019 8:39 pm

Re: NS FL2 B/B Q5

Post by NS_Tutor_Mathias » Tue Jul 16, 2019 1:55 pm

You are expected to know that Trisomy 21 is viable, as are normal humans (leftmost case). The passage and stem state that ROB carriers are viable too, although they are a little sneaky about this.

The other conditions presented would, as a matter of background knowledge, either not produce viable offspring or not even live to sexual maturity. Remember that having the normal amount of chromosomes of each kind is usually very important towards gene expression at the right levels. The sex chromosomes are a pretty major exception to this, where the consequences of loss and gain are often far less severe.
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