Select incorrect statement for gas vacuoles, which usually occur in cyanobacteria, purple and green photosynthetic bacteria :

Options

A. The are basically aggregates of a number of small, hollow cylindrical gas vesicles
B. Gas vesicles are permeable to water but are not permeable to atmospheric gases.
C. Because of gas vacuoles, these bacteria keep floating on or near the surface of water.
D. These vacuoles help the organisms in positioning themselves in the water column for trapping sunlight for photosynthesis , or for avoiding intense sunlight

Answer

**Step-by-Step Solution:**

1. **Understanding Gas Vacuoles**: Gas vacuoles are specialized structures found in certain bacteria, including cyanobacteria and photosynthetic bacteria. They provide buoyancy, allowing these organisms to float at specific depths in water where light for photosynthesis is optimal.

2. **Composition of Gas Vacuoles**: Gas vacuoles are composed of protein and are filled with air. Their structure allows them to maintain buoyancy in aquatic environments.

3. **Permeability of Gas Vacuoles**: A key feature of gas vacuoles is that they are permeable to gases (such as oxygen and carbon dioxide) but impermeable to water. This property is crucial for their function in buoyancy.

4. **Analyzing the Statements**: The question asks to identify the incorrect statement about gas vacuoles. The statements provided include:
- They are aggregates of small cylindrical gas vesicles (this is correct).
- Gas vesicles are permeable to water (this is incorrect).
- Gas vacuoles help bacteria float near the water surface (this is correct).

5. **Identifying the Incorrect Statement**: The statement that gas vesicles are permeable to water is incorrect, as they are actually impermeable to water. Therefore, this is the answer to the question.

**Final Answer**: The incorrect statement is: "Gas vesicles are permeable to water."

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