3. A couple, the father an A type and mother a B type, have a son that is O type

Question

3. A couple, the father an A type and mother a B type, have a son that is O type. What is the probability that they will have a child that is an AB-type daughter?

A.1.00

B.0.50

C.0.25

D.0.125

E.0.0625

4. In a case of disputed parentage, a child is O blood type, while the mother is blood type A. There is no dispute that the woman is the mother of the child. Which of the blood types below would exclude a male from being the father?

A.Only AB-type

B.Only A-type

C.Only B-type

D.Both A- and B-types

E.Only O-type

F.A-type, B-type, and O-type would be excluded

Please show all work and drawings! need to understand! thank you!!!

Explanation / Answer

3. It is given that the father has blood type A while mother has blood type B. A blood group can have genotype IAIA or IAIO and B blood type can have genotype IBIB or IBIO. However it is mentioned in the question that they have a son with O blood group. This means that the genotype of parents is as follows:

A type Father- IAIO

B type Mother-  IBIO

Let's find out the probability of an AB type daughter to be born to these parents.

Since both the parents are heterozygous therefore, their is an equal probability for the four types of blood group to occur in their offsprings i.e. their children can have any of these blood groups: A, B, AB or O. This means that the probability of blood type AB to occur is 1/4 or 0.25.

The probability of a daughter to be born to them is 1/2 or 0.5.

Thus, the probability of having an AB type daughter will be,

1/2 X 1/4 = 1/8

= 0.125

Thus, the right answer is option D.0.125.

4. A.Only AB-type

Since the child born has blood group O this means that the mother with blood group A has heterozygous genotype IAIO. A male with A, B or O blood type can contribute allele IO for the offspring to have O blood type but a father with AB blood type cannot contribute this allele IO. Thus, option A is the right answer.

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.