Remember that blood type is an example of codominance. Marty, who is heterozygous for type B blood, marries Patricia, who has type AB blood.

a. Show a Punnett square cross between Patricia and Marty. (2 pts)

b. What percentage of their children will potentially have type B blood? (1 pt)

c. What percentage of their children will potentially have type O blood? (1 pt)



Answer :

Certainly! Let's break down each part of the question step-by-step.

### Part A: Punnett Square Cross

1. Understanding the Genotypes:
- Marty is heterozygous for type B blood, so his genotype is [tex]\( BO \)[/tex].
- Patricia has type AB blood, so her genotype is [tex]\( AB \)[/tex].

2. Setting up the Punnett Square:

The possible gametes from Marty ([tex]\( BO \)[/tex]):
- B
- O

The possible gametes from Patricia ([tex]\( AB \)[/tex]):
- A
- B

Now, we'll create the Punnett square to visualize the possible genotypes of their children.

```
| B | O |
-----------------
A | AB | AO |
-----------------
B | BB | BO |
```

3. Possible Genotypes from the Cross:
- AB (from A and B)
- AO (from A and O)
- BB (from B and B)
- BO (from B and O)

### Part B: Percentage of Children with Type B Blood

Type B blood can be produced by the genotypes [tex]\( BB \)[/tex] and [tex]\( BO \)[/tex]. From our Punnett square, we can see:

- [tex]\( BB \)[/tex]
- [tex]\( BO \)[/tex]

Out of the four possible genotypes (AB, AO, BB, and BO), 2 of them (BB and BO) will have type B blood.

To find the percentage:
[tex]\[ \text{Percentage of Type B blood} = \left(\frac{2}{4}\right) \times 100\% = 50\% \][/tex]

So, 50% of their children will potentially have type B blood.

### Part C: Percentage of Children with Type O Blood

Type O blood can only be produced by the genotype [tex]\( OO \)[/tex]. From our Punnett square, we can see that no combination results in an [tex]\( OO \)[/tex] genotype.

To find the percentage:
[tex]\[ \text{Percentage of Type O blood} = \left(\frac{0}{4}\right) \times 100\% = 0\% \][/tex]

So, 0% of their children will potentially have type O blood.

### Summary:
a. The Punnett square is shown as follows:

```
| B | O |
-----------------
A | AB | AO |
-----------------
B | BB | BO |
```

b. 50% of their children will potentially have type B blood.

c. 0% of their children will potentially have type O blood.