How many types of gametes will be formed by genotype XxYyZZ ?

Options

A. Two
B. Four
C. Six
D. Eight

Answer

To determine the number of types of gametes formed by the genotype XxYyZZ, we can follow these steps:

### Step 1: Identify the heterozygous and homozygous alleles
- The genotype provided is XxYyZZ.
- In this genotype:
- Xx is heterozygous (X and x are different alleles)
- Yy is heterozygous (Y and y are different alleles)
- ZZ is homozygous (both alleles are Z)

### Step 2: Count the number of heterozygous pairs
- We have two heterozygous pairs: Xx and Yy.
- The homozygous pair (ZZ) does not contribute to the variety of gametes since it only produces one type of allele (Z).

### Step 3: Use the formula for the number of gametes
- The formula to calculate the number of types of gametes is given by \(2^n\), where \(n\) is the number of heterozygous pairs.
- Here, \(n = 2\) (from Xx and Yy).

### Step 4: Calculate the number of gametes
- Plugging the value of \(n\) into the formula:
\[ \text{Number of gametes} = 2^n = 2^2 = 4 \]

### Conclusion
- Therefore, the number of types of gametes formed by the genotype XxYyZZ is **4**.

### Answer
- The answer is **B) 4**.