Select the incorrect statement .

Options

A. The cell envelope consists of a tightly bound three layered structure , of which plasma membrane is the innermost layer
B. A specialized differentiated from of cell membrane called mesosome is the characteristic of prokaryotes.
C. Surface structures of the bacteria , like flagella , pili and fimbriae play a major role in motility .
D. Gas vacuoles are found in blue green and purple and green photosynthetic bacteria.

Answer

To solve the question, we need to analyze each of the statements provided and determine which one is incorrect.

### Step-by-Step Solution:

1. **Evaluate Statement 1**: "The cell envelope consists of tightly bound three-layered structure of which plasma membrane is the innermost layer."
- The cell envelope of prokaryotes indeed consists of three layers: the outer membrane, the peptidoglycan cell wall, and the innermost plasma membrane. This statement is **correct**.

2. **Evaluate Statement 2**: "A specialized differentiated form of cell membrane called mesosome is the characteristic feature of the prokaryotes."
- Mesosomes are indeed specialized structures formed by the invagination of the plasma membrane in prokaryotes. They are often associated with functions like cell division and DNA replication. This statement is **correct**.

3. **Evaluate Statement 3**: "Surface structures of bacteria like Flagella, Pili, Fimbriae play a major role in motility."
- While flagella are indeed responsible for motility in bacteria, pili and fimbriae are primarily involved in attachment and not in motility. Therefore, this statement is **incorrect**.

4. **Evaluate Statement 4**: "Gas vacuoles are found in blue-green and purple and green photosynthetic bacteria."
- Gas vacuoles are structures that help certain bacteria maintain buoyancy and are found in cyanobacteria (blue-green bacteria) as well as some purple and green photosynthetic bacteria. This statement is **correct**.

### Conclusion:
The incorrect statement is **Statement 3**: "Surface structures of bacteria like Flagella, Pili, Fimbriae play a major role in motility."

### Final Answer:
The incorrect statement is **Option 3**.

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