Which of the following statements about crossing over is true?

In humans, brown eye color (B) is dominant over blue eye color (b). A brown-eyed woman and a brown-eyed man mate and have a blue

Dmitry_Shevchenko [17]

Answer:

In the case of these two parents, a quarter of their children would have blue eyes.

Explanation:

It is not only possible, it is expected that this would happen an appreciable fraction of the time. Brown eyes are dominant. Suppose eye color were dependent on a single Mendelian gene with two alleles, Br for Brown eyes and Bl for Blue eyes. (As Tracey Bryan has explained, this is not true -- I want to explain what the answer would be even in the simple case.) This means the three possible combinations of two alleles give the following eye colors:

BrBr => Brown

BrBl => Brown

BlBl => Blue

Now suppose two brown-eyed people have a child. We can't tell from the fact that they have brown eyes which pairs of alleles they have. Each of them could have either BrBr or BrBl. Suppose they each have BrBl. When they are crossed (i.e., they have a child), the child gets one allele from its mother -- it has a 50-50 chance of getting either one -- and one allele from its father -- again it has a 50-50 chance of getting either one. So, the child has:

25% chance of getting Br from mother and Br from father => brown eyes;

25% chance of getting Br from mother and Bl from father => brown eyes;

25% chance of getting Bl from mother and Br from father => brown eyes;

25% chance of getting Bl from mother and Bl from father => blue eyes.

So in the case of these two parents, a quarter of their children would have blue eyes.

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4 years ago

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The belief that the experiences of women and men differ as a result of differences in anatomy is called:

Sergeu [11.5K]

Evolution caused different anatomy..

the brain is differently wired in men and womens

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