Cystic Fibrosis from EK today

[vinniekan]

Below is the problem from EK daily MCAT quiz.

My question is why can't the answer be 8? because the question asks for the maximum family members that "might be"

Their rational was that if both the oldest generation's are unaffected carriers, one of their children (a male and female) will likely to be affected. But likely isn't the same as have to be?

Assuming the genotype of the disease is recessive, couldn't parents, children, and uncle (the one not related) and all grandchildren (unaffected ones) have a chance to be unaffected carrier?

Confused...

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[Shadowplay]

I agree with the answer "8" as well. If both members of generation I were carriers, it would be assumed that 1/4 of their children (according to mendelein ratios) would have cystic fibrosis. They have only two children. Thus it is reasonable to see neither infected.

I found when I studied for my MCAT that sometimes the practice questions from kaplan and EK had incorrect answers or answers with faulty logic. Not many, but a few. This could be one of them.

Of course if I'm completely incorrect, and someone can explan why, that would be awesome too.

 

[coffeebythelake]

yes, correct answer is 8.

 

[vinniekan]

Thanks for help

 

[neil100]

Below is the problem from EK daily MCAT quiz.

My question is why can't the answer be 8? because the question asks for the maximum family members that "might be"

Their rational was that if both the oldest generation's are unaffected carriers, one of their children (a male and female) will likely to be affected. But likely isn't the same as have to be?

Assuming the genotype of the disease is recessive, couldn't parents, children, and uncle (the one not related) and all grandchildren (unaffected ones) have a chance to be unaffected carrier?

Confused...

Yup the answer should definitely be 8. The key word being maximum. The grandparents or the first gen. can theoretically be carriers and since you are asked the maximum number of carriers, you should count both of them. Why does EK have so many errors? who prepares there stuff? they really need to proofread or think about what they ask. Some of the stuff is not even MCAT type. I say if you are using EK for daily quizzes, then use mcatquestionaday instead. It's much better. I have found 4-5 errors on mcatquestionaday but the questions are CLOSER to the real thing. believe me on that. They really require you to apply knowledge and concepts at the 2ndary and tertiary level. Very little spitting out to do there.

 

[vinniekan]

Yup the answer should definitely be 8. The key word being maximum. The grandparents or the first gen. can theoretically be carriers and since you are asked the maximum number of carriers, you should count both of them. Why does EK have so many errors? who prepares there stuff? they really need to proofread or think about what they ask. Some of the stuff is not even MCAT type. I say if you are using EK for daily quizzes, then use mcatquestionaday instead. It's much better. I have found 4-5 errors on mcatquestionaday but the questions are CLOSER to the real thing. believe me on that. They really require you to apply knowledge and concepts at the 2ndary and tertiary level. Very little spitting out to do there.

Oh yeah I use them both daily. In fact, I've gone through the whole mcatquestionaday archive twice already...