Which of the following will be used to determine whether the organism is homozygous or heterozygous for a character ?

Options

A. back cross
B. test cross
C. reciprocal cross
D. dihybrid cross

Answer

To determine whether an organism is homozygous or heterozygous for a specific character, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Genotype and Phenotype**:
- **Genotype** refers to the genetic makeup of an organism (e.g., the alleles present).
- **Phenotype** refers to the observable physical traits of an organism (e.g., flower color).

2. **Define Homozygous and Heterozygous**:
- An organism is **homozygous** for a character if it has two identical alleles (e.g., AA or aa).
- An organism is **heterozygous** for a character if it has two different alleles (e.g., Aa).

3. **Identify the Crosses**:
- **Back Cross**: Crossing an F1 hybrid with one of its parents to determine genotype.
- **Test Cross**: Crossing an individual with a homozygous recessive individual to determine if the individual is homozygous or heterozygous.
- **Reciprocal Cross**: Crossing two organisms where the sexes are reversed.
- **Dihybrid Cross**: A cross between individuals that differ in two traits.

4. **Determine the Best Method**:
- The **test cross** is specifically designed to reveal whether an organism with a dominant phenotype is homozygous (AA) or heterozygous (Aa). By crossing it with a homozygous recessive individual (aa), the offspring's phenotypes will indicate the genotype of the parent.

5. **Conclusion**:
- The correct method to determine if an organism is homozygous or heterozygous for a character is the **test cross**.

### Final Answer:
The correct option is **B) Test Cross**.

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