When `F_(1)` generation hybrid tall Tt is crossed with dwarf tt parent, it is a case of :-

Options

A. Dihybrid cross
B. test cross
C. Crossing over
D. Reciprocal cross

Answer

To solve the question of what type of genetic cross occurs when an F1 generation hybrid tall plant (Tt) is crossed with a dwarf plant (tt), we can analyze the options provided: dihybrid cross, test cross, crossing over, and reciprocal cross.

### Step-by-Step Solution:

1. **Understanding the F1 Generation**:
- The F1 generation hybrid tall plant has the genotype Tt, where 'T' represents the dominant allele for tallness and 't' represents the recessive allele for dwarfness.
- The dwarf plant has the genotype tt, meaning it has two recessive alleles.

2. **Identifying the Cross**:
- When we cross Tt (tall) with tt (dwarf), we are trying to determine the genotypes of the offspring produced from this cross.

3. **Analyzing the Types of Crosses**:
- **Dihybrid Cross**: This involves two traits, which is not applicable here since we are only dealing with one trait (height).
- **Test Cross**: This is a cross between a hybrid (Tt) and a homozygous recessive (tt) to determine the genotype of the hybrid. This matches our scenario.
- **Crossing Over**: This is a process that occurs during meiosis where alleles are exchanged between homologous chromosomes, not directly relevant to our question.
- **Reciprocal Cross**: This involves switching the sexes of the parents in a genetic cross, which is also not applicable here since we are not changing the parental genotypes.

4. **Conclusion**:
- Since we are crossing a hybrid tall plant (Tt) with a dwarf plant (tt) to determine the genotype of the offspring, this is indeed a test cross.

### Final Answer:
The correct answer is **Test Cross**.

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