The diagram shows the blood group alleles of two people who are planning to have a child. The father has genotype IAi and the mother has genotype IBi. A hos...
Question 1 Report
The diagram shows the blood group alleles of two people who are planning to have a child. The father has genotype IAi and the mother has genotype IBi. A hospital laboratory uses this genetic information before checking compatible blood supplies.
(a) Name the blood group produced by genotype IAIB. [1]
(b) Complete boxes P, Q and R in the genetic diagram. [3]
(c) Use the completed diagram to state the probability that their child will have blood group O. [1]
(d) Explain why a person must have their blood group checked before receiving donated red blood cells. [2]
Answer Details
(a) Genotype \(I^AI^B\) produces blood group AB. [1] Both alleles are expressed.
(b) Combining one allele from each parent gives:
| Father's gamete | Mother's gamete | Offspring genotype |
|---|---|---|
| \(I^A\) | \(I^B\) | \(I^AI^B\) (P) [1] |
| \(i\) | \(I^B\) | \(I^Bi\) (Q) [1] |
| \(i\) | \(i\) | \(ii\) (R) [1] |
(c) Only \(ii\) gives blood group O. One of the four equally likely outcomes is \(ii\), so the probability is \(\frac14\), or 25%. [1]
(d) If donated red blood cells have antigens that are incompatible with the recipient, the recipient's antibodies may recognise those antigens. [1] This can cause red blood cells to clump together (agglutinate) or be destroyed. [1]
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