Which one of the following is not true for the experiments of Mendel on pea?

Options

A. His experiments had small sampling size
B. He choose characters of two contrasting states
C. He used true-breeding lines
D. His observations were based on natural, open pollination

Answer

To determine which statement is not true regarding Mendel's experiments on pea plants, we will analyze each of the provided options step by step.

### Step-by-Step Solution:

1. **Understanding Mendel's Work**: Mendel is known as the father of genetics due to his pioneering work with pea plants (Pisum sativum). He conducted experiments to understand how traits are inherited through generations.

2. **Evaluating the Options**:
- **Option 1**: "His experiments had small sampling size."
- This statement is incorrect. Mendel's experiments involved a large number of pea plants, allowing him to gather significant data and reduce the impact of chance deviations.

- **Option 2**: "He chose characters of two contrasting states."
- This statement is true. Mendel selected traits that had clear contrasting forms, such as tall vs. short plants, and green vs. yellow seeds.

- **Option 3**: "He used true breeding lines."
- This statement is also true. Mendel ensured that he used true breeding plants, which consistently produced offspring with the same traits when self-pollinated.

- **Option 4**: "His observations were based on natural and open pollination."
- This statement is true as well. Mendel utilized natural and controlled open pollination methods to study the inheritance of traits.

3. **Conclusion**: After evaluating all options, we find that the statement "His experiments had small sampling size" is not true. Mendel's sampling size was large, which was essential for the reliability of his results.

### Final Answer:
The statement that is not true for Mendel's experiments on pea plants is: **"His experiments had small sampling size."**

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