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A man with type A- blood and a woman with type AB+ blood have a child. Which blood type is impossible for that child to have?

Correct answer: D. O-.

  • A. A-.
  • B. B-.
  • C. AB+.
  • D. O-.

Explanation

The ABO blood type system is based on the presence of two antigens (A and B) on the surface of red blood cells and two antibodies (anti-A and anti-B) in the plasma. In this scenario, the mother has both A and B antigens on her red blood cells (AB blood type) and the father has only A antigen (A- blood type). When these two blood types are combined, the possible blood types for their child are A, B, AB, or O. However, the child cannot inherit the B antigen from either parent because the father does not have it, so the child cannot have an AB blood type. Additionally, the child cannot have type O blood type because both parents must contribute an O allele, which means the child must inherit two O alleles. Since the father does not have an O allele, the child cannot have type O blood type. Therefore, the child must have either A or B blood type.

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Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.

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