Question

QUESTION 5 Let's go back to an example you read about in this lab. Consider two parents whose blood types are AB and Oo. o A B In the cross AB x 00 in the punnett square above what percentage of offspring are type A? QUESTION 6 In the cross AB x 00 what percentage of offspring are type B? QUESTION 7 In the cross AB x 00 What percentage of offspring are type o? QUESTION 8 In the AB x 00 cross what percentage of offspring are homozygous for type A? QUESTION 9 What percentage of offspring are heterozygous for any of the blood types in the Punnet Square?

Answer 1

1) In a cross between parents having blood type AB and OO, the following Punnet square is formed:-

AB/OO	O	O
A	AO	AO
B	BO	BO

ABO blood grouping in humans is an example of codominance where the two alleles are dominant over a third recessive allele and neither allele from the two alleles can mask the other allele.

Here, A and B are dominant alleles and O is a recessive allele.

So, in the above Punnet square, the percentage of offsprings with blood group A = 50% (AO genotype represents blood type A)

2) The percentage of offsprings having blood type B (BO genotype) = 2/4 * 100

= 1/2 * 100

= 50%

3) Percentage of offsprings with O blood group is 0% because in order to have blood type O, the offspring must have homozygous recessive genotype that is OO and in this Punnet square it is not possible.

4) Percentage of offsprings homozygous for type A is 0% because AA represents homozygous for type A and in the cross of AB and OO it is not possible. There is possibility of having only heterozygous A type (AO).

5) Percentage of offsprings heterozygous for any of the blood types in the Punnet square is 100% because cross of AB and OO results in the formation of only heterozygous genotypes (AO and BO), therefore, offsprings will have either heterozygous type A or heterozygous type B.