The mutations that involve addition, deletion or substitution of a single base pair in a gene are referred to as

Options

A. point mutations
B. lethal mutations
C. silent mutations
D. retrogressive mutations

Answer

### Step-by-Step Solution:

1. **Understanding Mutations**:
- Mutations are changes in the genetic material (DNA) that can occur due to various factors such as environmental influences or radiation.

2. **Types of Mutations**:
- Mutations can be classified based on the nature of the change in the DNA sequence. The question specifically refers to mutations that involve the addition, deletion, or substitution of a single base pair.

3. **Identifying the Type of Mutation**:
- When a mutation involves a change at a single point in the DNA sequence (i.e., a single base pair), it is referred to as a **point mutation**. This is because the change occurs at a specific point in the sequence.

4. **Exploring Other Types of Mutations**:
- While point mutations involve single base changes, other types of mutations include:
- **Lethal mutations**: These can lead to the death of an organism or significantly reduce its lifespan.
- **Silent mutations**: These involve changes in the nucleotide sequence that do not affect the amino acid sequence of the protein.
- **Retrogressive mutations**: These refer to the loss of non-essential traits over time.

5. **Conclusion**:
- Based on the definition and characteristics of the mutations described, the correct answer to the question is **point mutation**.

### Final Answer:
The mutations that involve addition, deletion, or substitution of a single base pair in a gene are referred to as **point mutations**.

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