Which one of the following is an incorrect statement regarding mycoplasma?

Options

A. They lack a cell wall,
B. They are the smallest living cells.
C. They cannot survive without oxygen.
D. They are pathogenic in plants and animals.

Explanation

To determine the incorrect statement regarding mycoplasma, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Mycoplasma**: Mycoplasma is a genus of bacteria known for lacking a cell wall. This characteristic is essential in distinguishing them from other bacteria.

2. **Evaluate the Statements**: We need to analyze each of the provided statements regarding mycoplasma to identify which one is incorrect.

3. **Statement Analysis**:
- **Statement 1**: "They lack a cell wall."
- This statement is **correct**. Mycoplasma indeed lacks a cell wall.
- **Statement 2**: "They are the smallest living cells."
- This statement is **correct**. Mycoplasma are among the smallest known living cells, with sizes ranging from 0.1 to 0.15 micrometers.
- **Statement 3**: "They cannot survive without oxygen."
- This statement is **incorrect**. Mycoplasma can survive in both aerobic (with oxygen) and anaerobic (without oxygen) conditions.
- **Statement 4**: "They are pathogenic in plants and animals."
- This statement is **correct**. Mycoplasma can cause diseases in both plants and animals.

4. **Identify the Incorrect Statement**: Based on the analysis, the incorrect statement is that "they cannot survive without oxygen."

### Conclusion:
The incorrect statement regarding mycoplasma is: **"They cannot survive without oxygen."**

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