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