Tonoplast is a

Options

A. Plasma membrane
B. Vacuolar membrane
C. Cytoplasmic membrane
D. all of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Term "Tonoplast":**
- Tonoplast is a specific type of membrane found in plant cells. It is important to identify what it surrounds and its functions.

2. **Identifying the Function of Tonoplast:**
- The tonoplast is the membrane that encloses the vacuole in plant cells. Vacuoles are large, fluid-filled organelles that play a key role in maintaining the cell's turgor pressure and storing substances.

3. **Characteristics of Tonoplast:**
- The tonoplast is semi-permeable, meaning it allows certain substances to pass through while blocking others. This characteristic is crucial for the regulation of the internal environment of the vacuole.

4. **Role of Protein Pumps:**
- The tonoplast contains various protein pumps that are involved in the active transport of ions and other molecules into and out of the vacuole. This helps in maintaining osmotic balance and regulating the vacuole's contents.

5. **Evaluating the Options:**
- The options given are:
a) Plasma membrane
b) Vacuolar membrane
c) Cytoplasmic membrane
d) All of these
- Based on the understanding that the tonoplast specifically surrounds the vacuole, it can be identified as a vacuolar membrane.

6. **Conclusion:**
- Therefore, the correct answer is that tonoplast is a **vacuolar membrane**.

**Final Answer:**
- The correct option is **b) Vacuolar membrane**.

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