To determine heterozygosity of a cross, one has to perform a) Backcross b) Reciprocal cross c) Testcross d) Any of these

Options

A. Backcross
B. Reciprocal cross
C. Testcross
D. Any of these

Answer

To determine the heterozygosity of a cross, we need to analyze the different types of crosses mentioned in the options and their purposes.

### Step-by-Step Solution:

1. **Understanding the Crosses**:
- **Backcross**: This is a cross between the progeny (offspring) and one of its parents. The purpose of a backcross is often to bring out certain traits or to confirm the genotype of the offspring.
- **Reciprocal Cross**: This involves reversing the phenotypes of the parents in the original cross. It helps to determine if the traits are sex-linked or influenced by the sex of the parent.
- **Test Cross**: This is a specific type of cross where the F1 progeny (first filial generation) is crossed with a homozygous recessive parent. The main purpose is to determine the genotype of the F1 progeny.

2. **Identifying the Purpose of Each Cross**:
- The backcross can provide information about traits but does not specifically determine heterozygosity.
- The reciprocal cross can help understand the influence of sex on traits but does not directly determine heterozygosity.
- The test cross is specifically designed to reveal whether the F1 progeny is homozygous or heterozygous by observing the phenotypes of the offspring produced.

3. **Conclusion**:
- Since the test cross is the only method that allows us to definitively determine whether the F1 progeny is heterozygous or homozygous, it is the correct choice for determining heterozygosity.

### Final Answer:
The correct option is **c) Testcross**.

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