Mendel's Law was estabilished when :-

Options

A. Two `F_(1)` hybrids are crossed
B. One parent is crossed with `F_(1)` hybrid
C. Two pure breeding contrasting characters are crossed
D. None of the above

Answer

To answer the question "Mendel's Law was established when?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Mendel's Experiment**: Mendel conducted experiments using pea plants to study inheritance patterns. He focused on traits such as height (tall vs. dwarf).

2. **Setting Up a Monohybrid Cross**: In a typical monohybrid cross, Mendel would take two pure breeding plants with contrasting traits. For example, a pure tall plant (TT) and a pure dwarf plant (tt).

3. **F1 Generation**: When these two pure parents are crossed, the first filial generation (F1) consists of all heterozygous offspring (Tt). At this stage, we observe that all offspring exhibit the dominant trait (tall).

4. **Selfing the F1 Hybrid**: To establish Mendel's laws, the next step is to self-fertilize the F1 hybrid (Tt). This means allowing the F1 plants to breed among themselves.

5. **F2 Generation**: The selfing of the F1 generation produces the second filial generation (F2), which has the following genotypic ratio: 1 TT (homozygous tall) : 2 Tt (heterozygous tall) : 1 tt (homozygous dwarf). This results in a phenotypic ratio of 3 tall : 1 dwarf.

6. **Establishing Mendel's Law**: It is through the analysis of the F2 generation that Mendel was able to establish his laws of inheritance, particularly the Law of Segregation and the Law of Independent Assortment.

7. **Conclusion**: Therefore, Mendel's laws were established when two F1 hybrids (Tt) were crossed, leading to the observation of the 3:1 phenotypic ratio in the F2 generation.

### Final Answer:
Mendel's Law was established when two F1 hybrids were crossed.

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