2. A man with type AB blood is married to a woman also with type AB blood. What proportion of their children will have: Show the Punnett square: A blood? __ B blood? __ blood __ AB blood __

## Step 1The problem involves the inheritance of blood types in humans. The ABO blood group system is determined by the ABO gene, which has three alleles: , , and . The and alleles are co-dominant, meaning that if both are present, they will both be expressed. The allele is recessive to both and .## Step 2A person with type AB blood has one allele and one allele. When they reproduce, they can pass on either the or allele to their offspring.## Step 3The Punnett square for this cross would look like this:| | | ||---|---|---|| | | || | | |## Step 4From the Punnett square, we can see that there are four possible combinations of alleles that the offspring could have:- : This would result in type A blood.- : This would result in type AB blood.- : This would also result in type AB blood.- : This would result in type B blood.## Step 5Therefore, the proportion of their children that will have:- A blood: 1 out of 4, or 25%- B blood: 1 out of 4, or 25%- AB blood: 2 out of 4, or 50%- O blood: 0 out of 4, or 0%