BIOLOGY 100 - Human Biology

GENETICS PRACTICE PROBLEMS

Part 3

Question 1

Yellow guinea pigs crossed with white ones always produce cream colored offspring. Two cream colored guinea pigs when crossed produced yellow, cream and white offspring in the ratio of l yellow: 2 cream: l white. How are these colors inherited?

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Question 2

In humans the blood groups are produced by various combinations of three alleles I^A, I^B, and i. Blood type A is caused by either I^A I^A or I^A i; type B by I^B I^B or I^B i; type AB by I^A I^B; and type O by i i. Suppose a child is of blood type A and the mother is of type 0. What type or types may the father belong to?

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Question 3

Suppose a father of blood type A and a mother of blood type B have a child of type O. What blood types are possible in their subsequent children?

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Question 4

Suppose a father of blood type B and a mother of blood type O have a child of type O. What are the chances that their next child will be blood type O? Type B? Type A? Type AB?

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Question 5

Suppose a father and mother claim they have been given the wrong baby at the hospital. Both parents are blood type A. The baby they have been given is blood type O. What evidence bearing on this case does this fact have?

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Question 6

A mother and father with normal color vision produce six male children, two of whom exhibit red-green colorblindness. Their five female children exhibit normal color vision. Ignoring the fact that these parents ought to seek some family planning advice, explain the inheritance of red-green colorblindness in their male children.

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e-mail Dave Krupp

revised 21 August 2001