A useful process for determining whether an individual is homozygous or heterozygous is :-

Options

A. Cross-breeding
B. Self fertilization
C. Back-crossing
D. Test cross

Answer

To determine whether an individual is homozygous or heterozygous, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- **Homozygous**: An individual with two identical alleles for a particular gene (e.g., AA or aa).
- **Heterozygous**: An individual with two different alleles for a particular gene (e.g., Aa).

2. **Identify the Methods**:
- We need to evaluate different methods to determine zygosity (homozygous vs. heterozygous).

3. **Evaluate Crossbreeding**:
- Crossbreeding involves mating individuals from different breeds or varieties. This method does not provide information about the zygosity of an individual, as it focuses on producing offspring rather than analyzing the genetic makeup of a single individual.

4. **Evaluate Self-Fertilization**:
- Self-fertilization is the union of male and female gametes from the same individual. While it can produce offspring, it does not directly reveal whether the individual is homozygous or heterozygous.

5. **Evaluate Back Crossing**:
- Back crossing involves crossing a hybrid with one of its parents. This method can help in breeding but does not specifically determine the zygosity of the individual in question.

6. **Evaluate Test Crossing**:
- Test crossing is the process of crossing an individual of unknown zygosity with a pure recessive individual. This method allows us to observe the offspring's phenotypes. If all offspring display the dominant trait, the individual is likely homozygous. If there is a mix of traits, the individual is heterozygous.

7. **Conclusion**:
- The most effective method for determining whether an individual is homozygous or heterozygous is **test crossing**.

### Final Answer:
A useful process for determining whether an individual is homozygous or heterozygous is **test crossing**.

---