Question

1. If a person that has blood type O has a child with a person that has blood type AB, what is the probability that the child will be blood type A?

	a.	0%
	b.	25%
	c.	50%
	d.	75%
	e.	100%

2. Red-green color blindness is inherited through an X-linked, recessive allele (b). Two parents, Fred and Ginger, have normal vision. They have two daughters, Takiyah and Kelly, who also have normal vision, and a color-blind son, David. What is the probability that Fred and Ginger will have another color blind son?

	a.	0%
	b.	25%
	c.	50%
	d.	75%
	e.	100%

Answer 1

1. c) 50%

• Ist person: Alleles : O and O

As O blood group is recessive.

• 2nd person: Alleles: A and B

In the case of AB Blood group.

Probability for blood type A:

Alleles will be A and O.

Either AO or BO is the possibility.

Therefore, probability for A blood group is 50%.

2. b) 25%

Parents normal:

Fred normal means XY normal.

Ginger normal but since son is color blind. It means she is the carrier XX'

Now possibilities are XX, XY, X'Y, and XX'.

X'Y : Color blind son. ( As XY is a hemizygous condition)

That is 1/4 or 25%