Question

3. Alleles for the A and B blood cell antigens are codominant. The condition where no antigens are present on the blood cells (type O blood) is a recessive trait. Which set of parents can most likely produce a child with type O blood? (SC.912.L.16.1)

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1 point
one parent with type AB blood, and the other parent with type A blood
one parent with type AB blood and the other parent with type O blood
one parent with heterozygous type A blood, and the other parent with type O blood
one parent with homozygous type A blood, and the other parent with homozygous type B blood
4. Hitchhiker's thumb (H) is dominant to no hitchhiker's thumb (h). A woman who does not have hitchhiker's thumb marries a man who is heterozygous for hitchhiker's thumb. What is the probable genotypic ratio of their children? (SC.912.L.16.1)

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1 point
0% Hh: 100% hh
50% Hh: 50% hh
75% Hh: 25% hh
100% Hh: 0% hh

Answer 1

3. one parent with heterozygous type A blood, and the other parent with type O blood.
- Explanation: IAi × ii can produce ii (type O) in 50% of offspring.

4. 50% Hh: 50% hh.
- Explanation: Hh × hh gives half Hh (hitchhiker's thumb) and half hh (no hitchhiker's thumb).