Which of the following statements is NOT correct?

Options

A. Mutations provide variation upon which natural selection can act.
B. The vast majority of mutations produce alleles which are dominant.
C. Mutations arise spontaneously, infrequently and at random.
D. Mutation rate can be increased by artificial means.

Answer

To determine which statement is NOT correct among the given options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Analyze the First Statement:**
- **Statement:** "Mutations provide variations upon which natural selection can act."
- **Evaluation:** This statement is correct. Mutations are indeed the source of genetic variation, which is essential for natural selection to occur.

2. **Analyze the Second Statement:**
- **Statement:** "The vast majority of mutations produce alleles which are dominant."
- **Evaluation:** This statement is NOT correct. In reality, most mutations are recessive, and dominant mutations are less common. Thus, this statement is false.

3. **Analyze the Third Statement:**
- **Statement:** "Mutations arise spontaneously."
- **Evaluation:** This statement is correct. Mutations can occur randomly and spontaneously in the genetic material.

4. **Analyze the Fourth Statement:**
- **Statement:** "The rate of mutations can increase by artificial means."
- **Evaluation:** This statement is also correct. Scientists can induce mutations through various artificial methods, such as radiation or chemical exposure.

### Conclusion:
The statement that is NOT correct is the second one: "The vast majority of mutations produce alleles which are dominant."

### Final Answer:
The incorrect statement is: **"The vast majority of mutations produce alleles which are dominant."**

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