What is not true about mutation according to Hugo de Vries theory?

Options

A. They are large and discontinuous changes
B. Mutations are random and directionless
C. They are heritable and establish new species
D. A single step large mutation to produce a species can never occur

Answer

To determine which statement is not true about mutation according to Hugo de Vries' theory, we will analyze each of the given options step by step.

### Step 1: Analyze the first statement
**Statement:** "They are large and discontinuous changes."
- **Explanation:** According to Hugo de Vries, mutations are indeed large and discontinuous. They do not occur in a gradual manner but rather as significant changes that can appear suddenly. This statement is true.

### Step 2: Analyze the second statement
**Statement:** "Mutations are random and directionless."
- **Explanation:** This statement is also true. Mutations occur randomly and are not directed towards any specific outcome or goal. They can happen in any organism and at any time, making this statement accurate.

### Step 3: Analyze the third statement
**Statement:** "They are heritable and establish new species."
- **Explanation:** This statement is true as well. Mutations that occur in germ cells can be passed on to the next generation, and over time, these heritable mutations can lead to the formation of new species. Therefore, this statement is correct.

### Step 4: Analyze the fourth statement
**Statement:** "A single step large mutation to produce a species can never occur."
- **Explanation:** This statement is false. According to de Vries' theory, a large mutation can indeed lead to the formation of a new species in a single step, a concept known as "saltation." Therefore, this statement is not true.

### Conclusion
The statement that is not true about mutation according to Hugo de Vries' theory is:
**"A single step large mutation to produce a species can never occur."**

Thus, the correct answer is option D.

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