Solutions to Genetics Practice Problems
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- If the parents have blood types AB and O, what blood types
can their children have?
The Ab parent has genotype IAIB, the O parent genotype ii. Hence, possible offspring are
IAi = A and IBi = B
- A mother has blood type O, and her child has blood type O. What
are the possible blood types of her father?
The genotype of the mother and her child are both ii. Hence, the father must contribute an i allele, and hence could be IAi = type A,
IBi = type B, or ii = type O
- If the father is AB negative and the mother O positive, what are
the possible blood types for their children?
If the father is negative, his genotype is --, while the mother could be -+ or ++. Hence, the possible blood types are A+, A-, B+, and B-.
- An AB negative blood strain is found at a crime screen. John
Smith is a possible suspect, but is still at large. If John's father has
type O positive blood, could the blood stain have come from John?
An AB negative blood type implies a genotype of
IAIB--. Since John's father is O positive, his possible genotypes are ii++ and ii+-. Hence, John could have negative blood, but he would be either A, B, or O, but never AB/