The determine the genotype of a tall plant at `F_(2)` Mendel performed

Options

A. Self pollination
B. Cross pollination with homozygous dominant
C. Cross pollination with homozygous recessive
D. Cross pollinated with plant of `F_(2)` having intermediate genomic combination.

Answer

To determine the genotype of a tall plant in the F2 generation, Mendel performed the following steps:

### Step-by-Step Solution:

1. **Understanding the Traits**: Mendel studied the inheritance of traits in garden peas (Pisum sativum), focusing on the trait of plant height, which has two contrasting forms: tall (dominant) and dwarf (recessive).

2. **Identifying Alleles**: In this case, the tall allele is represented by 'T' (dominant) and the dwarf allele by 't' (recessive).

3. **Monohybrid Cross**: Mendel began with a monohybrid cross between a pure tall plant (TT) and a pure dwarf plant (tt).

4. **F1 Generation**: The offspring (F1 generation) from this cross all exhibited the tall phenotype (Tt) because the tall allele is dominant over the dwarf allele.

5. **F2 Generation**: When the F1 plants (Tt) were self-pollinated, the F2 generation was produced. The phenotypic ratio observed in the F2 generation was 3 tall plants to 1 dwarf plant.

6. **Genotypic Ratio**: The genotypic ratio in the F2 generation is 1 homozygous tall (TT) : 2 heterozygous tall (Tt) : 1 dwarf (tt).

7. **Determining Genotype of Tall Plants**: To determine whether a tall plant is homozygous (TT) or heterozygous (Tt), Mendel used a test cross. This involves crossing the tall plant with a homozygous recessive plant (tt).

8. **Interpreting Results of Test Cross**:
- If the tall plant is homozygous (TT), all offspring will be tall (100% tall).
- If the tall plant is heterozygous (Tt), the offspring will be in a 1:1 ratio of tall to dwarf (50% tall and 50% dwarf).

9. **Conclusion**: By observing the offspring from the test cross, Mendel could determine the genotype of the tall plant in the F2 generation.