Number of genotypes produced when individuals of genotype 'YyRrTt' are crossed with each other

Options

A. 4
B. 45
C. 28
D. 27

Answer

To determine the number of genotypes produced when individuals of genotype 'YyRrTt' are crossed with each other, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotype**: The given genotype is 'YyRrTt'. This indicates that there are three genes, each with two alleles (Y/y, R/r, T/t).

2. **Count the Heterozygous Loci**:
- In the genotype 'YyRrTt', we see that:
- Yy is heterozygous (Y and y)
- Rr is heterozygous (R and r)
- Tt is heterozygous (T and t)
- Therefore, there are a total of 3 heterozygous loci.

3. **Use the Formula for Genotype Calculation**:
- The formula to calculate the number of different genotypes from a cross involving heterozygous individuals is given by \(3^n\), where \(n\) is the number of heterozygous loci.
- Here, since we have 3 heterozygous loci, we substitute \(n = 3\) into the formula.

4. **Calculate the Number of Genotypes**:
- \(3^3 = 27\)
- Thus, the total number of different genotypes produced from this cross is 27.

5. **Conclusion**:
- Therefore, when individuals of genotype 'YyRrTt' are crossed with each other, they produce a total of 27 different genotypes.

### Final Answer:
The number of genotypes produced is **27**.

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