Mendel's law of segeration is based upon the `F_(2)` ratio of

Options

A. `1:2`
B. `9:3:3:1`
C. `1:2:1`
D. `3:1`

Answer

To solve the question regarding Mendel's law of segregation and its basis on the F2 generation ratio, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Mendel's Experiments**:
- Mendel conducted experiments with pea plants to study inheritance. He focused on traits such as plant height, where tall (T) is dominant over dwarf (t).

2. **Parental Generation (P)**:
- Mendel started with two purebred plants: one homozygous tall (TT) and one homozygous dwarf (tt).

3. **Formation of F1 Generation**:
- When these two plants were crossed, all offspring in the F1 generation were heterozygous (Tt) and exhibited the dominant trait, which is tall.

4. **Selfing the F1 Generation**:
- Mendel then allowed the F1 plants (Tt) to self-pollinate to produce the F2 generation.

5. **Analyzing the F2 Generation**:
- The F2 generation resulted in a phenotypic ratio of 3 tall plants to 1 dwarf plant (3:1). This means that out of every four plants, three were tall and one was dwarf.

6. **Genotypic Ratio**:
- The genotypic ratio from the F2 generation is 1 homozygous dominant (TT): 2 heterozygous (Tt): 1 homozygous recessive (tt), which is expressed as 1:2:1.

7. **Conclusion**:
- Mendel's law of segregation states that during gamete formation, the alleles for a trait segregate from each other so that each gamete carries only one allele for each trait. This law is based on the observed F2 generation ratio of 3:1.

### Final Answer:
Mendel's law of segregation is based upon the F2 ratio of **3:1**.

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