Genes A and B are on different chromosomes. What fraction of the offspring of the cross

AaBb x AaBb will be homozygous for all the dominant alleles?

A. 1/64

B 3/9

C 1/32

D.1/16

B 1/9

The answer is D. May I know the explanation?

Genes A and B are on different chromosomes. What fraction of the offspring of the cross

AaBb x AaBb will be homozygous for all the dominant alleles?

A. 1/64

B 3/9

C 1/32

D.1/16

B 1/9

The answer is D. May I know the explanation?

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is the answer 1/16? i think you made a small typo

here how I solved this question:

from the first Aa you have 1/2 chance of getting either A or the a.

from Bb you again have a 1/2 chance of getting the either B or b.

for the second one in the cross we do this again

we have 1/2 chance of getting one of the A or a from this one and the same for B or b.

at the end the probability we need is the multiplication of all which means:

1/2x1/2x1/2/x1/2= 1/16

let me know if you got confused in any way

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I would agree with @nihantokar

I have compared it with F2 gen of mendelian dihybrid cross. Or it could also be solved by product rule as mentioned above by Nihan.

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@Ibraheem_Saeed that’s the best way to solve this question in order to not get confused but as in the exam we have limited time I wanted to use the product rule.

thanks for sharing!

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Isn’t is 1/16?

Because like homozygous for DOMINANT Alleles is essentially AABB. Which only happens once in a dihybrid cross.

Same I also think it is a typographical error

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Yes it was a typo. I get it. Thank you.

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