Question

Questions 12-16 relate to the use of blood group typing to determine paternity (who is the father?).

Question 12

A child's phenotype for blood type is O. Indicate their potential genotype(s) below.

Select one or more:

a. I^AI^A

b. I^Ai

c. I^BI^B

d. I^Bi

e. I^AI^B

f. ii

Question 13

The above child's mother has blood type A and knows her genotype is heterozygous. Indicate her potential genotype(s) below.

Select one or more:

a. I^AI^A

b. I^Ai

c. I^BI^B

d. I^Bi

e. I^AI^B

f. ii

The mother from Q13 is uncertain who is the biological father of her child. One of two men could be the father.

Question 14

Male 1 has blood type B. Indicate his potential genotype(s) below.

Select one or more:

a. I^AI^A

b. I^Ai

c. I^BI^B

d. I^Bi

e. I^AI^B

f. ii

Question 15

Male 2 has blood type AB. Indicate his potential genotype(s) below.

Select one or more:

a. I^AI^A

b. I^Ai

c. I^BI^B

d. I^Bi

e. I^AI^B

f. ii

Question 16

Construct a punnet square for ABO blood typing for the mother and two males from the previous questions, to determine the paternity of the child and his likely genotype.

Summary: The mother knows her genotype is heterozygous.

	Phenotype
Mother	A
Male 1	B

Select one:

a. Male 1 is likely to the be the father and his genotype is I^BI^B.

b. Male 1 is likely to the be the father and his genotype is I^Bi.

c. Male 1 is likely to the be the father and his genotype is ii.

d. Male 2 is likely to the be the father and his genotype is I^AI^B.

Answer 1

The genotype and corresponding phenotypes for blood groups are :

IAIA and IAi for blood group A. IBIB and IBi for blood group B. IAIB for blood group AB. ii for blood group O.

Q12. The only genotype possible for blood group O is ii. Answer: f.ii

Q13. The mother has blood group A and knows her genotype is heterozygous. Thus the only possible genotype for the mother is IAi. (IAIA would have been homozygous). Answer : b. IAi

Q14. Male 1 has blood type B. Thus potential genotypes are IBIB and IBi. Answer : c. IBIB and d.IBi.

Q15. Male 2 has blood type AB. Thus potential genotype is IAIB. Answer : e. IAIB.

Q16. The child has two 'i' alleles. One 'i' allele he obtained from his mother(mother is IAi). The child has to obtain the other 'i' allele from the father. Male 2 can only produce gametes with IA and IB alleles and no i allele. Thus Male 1 must have produced the gamete with the other i allele. Thus Male 1 must have been IBi (and not IBIB) and he must have been the father. Answer: b. Male 1 is likely to the be the father and his genotype is IBi.