Which of. These statements about Mycoplasma is / are true ?
I. Mycoplasma is the smallest cell known.
II . They are not prokaryotic in nature .
III. They can respire only in the presence of oxygen .
IV. They lack cell walls.

Options

A. I and II
B. I and IV
C. I , II and III
D. II and IV

Answer

To determine which statements about Mycoplasma are true, let's analyze each statement one by one.

### Step 1: Analyze Statement I
**Statement I:** Mycoplasma is the smallest cell known.
- Mycoplasma is indeed recognized as one of the smallest known cellular organisms. They are bacteria that lack a cell wall and are typically smaller than many other bacteria.
**Conclusion:** This statement is **true**.

### Step 2: Analyze Statement II
**Statement II:** They are not prokaryotic in nature.
- Mycoplasma are classified as prokaryotes. They are single-celled organisms that lack a nucleus and other membrane-bound organelles, which is characteristic of prokaryotic cells.
**Conclusion:** This statement is **false**.

### Step 3: Analyze Statement III
**Statement III:** They can respire only in the presence of oxygen.
- Mycoplasma can perform both aerobic and anaerobic respiration. They do not exclusively require oxygen to respire, meaning they can survive and generate energy in the absence of oxygen as well.
**Conclusion:** This statement is **false**.

### Step 4: Analyze Statement IV
**Statement IV:** They lack cell walls.
- One of the defining characteristics of Mycoplasma is that they do not have a cell wall. This is why they are resistant to antibiotics that target cell wall synthesis.
**Conclusion:** This statement is **true**.

### Final Conclusion
Based on the analysis:
- **True Statements:** I and IV
- **False Statements:** II and III

Therefore, the correct answer is that statements I and IV about Mycoplasma are true.