Crossover frequency bio question:

[192LT192]

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If 4 genes A, B, C, D occur on same chromosome use the following crossover frequencies to determine the order of the genes on the chromosome.

A+D= 5%
B+C= 15%
A+C= 30%
C+D= 35%
B+D= 50%

how do i go about doing this type of question? ive encountered it a few times going through cliffs and i never know. their explanation didnt help too much.

also, what do you guys think of the full length AP bio practice tests cliffs has (in the book and on the cd. there are 2 in the back of the book and 4 bonus ones on the cd)? are the bio questions comparable to the dat bio questions in terms of difficulty? or are there questions a joke?

thanks guys!!

 

[brightsmiles9]

The way I like to do these type of problems is actually draw it out because Im a visual learner. So ill make the best attempt to draw it out here

B C A D
15 30 5

Idk if you can understand it but based on drawing it out, you can conclude the missing distances. Like AC is just 35-5 from AD. Let me know if its not clear, hope that helped.

And with the AP bio questions, I mean more questions wouldnt hurt. GOOD LUCK!

 

[192LT192]

you got it right! the explanation cliffs gives is showing me to draw tick marks and to show all these possibilities and then crossing out some letters. not worth explaining. they just made it more complicated. thanks!
so more practice is better but just curious how the difficulty of the cliffs questions to the dat questions compare...

 

[nze82]

you got it right! the explanation cliffs gives is showing me to draw tick marks and to show all these possibilities and then crossing out some letters. not worth explaining. they just made it more complicated. thanks!
so more practice is better but just curious how the difficulty of the cliffs questions to the dat questions compare...

Sometimes it's possible to answer these types of questions by looking at the largest frequency and the smallest. The largest represents the two genes that are farthest apart and the smallest represents the two genes that are closest. When you have this information, you can start eliminating some of the choices and that may help you have a better shot at the correct answer.