Read the following statements and choose the correct option. (A) Osmotic pressure is equivalent to the osmotic potential but the sign is opposite. (B) During plasmolysis water is first lost from the vacuole then from the cytoplasm. (C) The process of plasmolysis is usually reversible

Options

A. Only A is correct
B. Only B is incorrect
C. Both B and C are correct
D. Both A and B are correct

Answer

To solve the question, we need to evaluate each of the three statements provided and determine their correctness.

1. **Statement A**: "Osmotic pressure is equivalent to the osmotic potential but the sign is opposite."
- **Explanation**: Osmotic pressure is indeed related to osmotic potential. Osmotic potential is typically expressed as a negative value because it represents the tendency of water to move into a solution. In contrast, osmotic pressure is a positive value that indicates the pressure required to prevent water from entering the solution. Therefore, this statement is correct.

2. **Statement B**: "During plasmolysis, water is first lost from the vacuole then from the cytoplasm."
- **Explanation**: In the process of plasmolysis, water is lost from the cytoplasm first, followed by water loss from the vacuole. This statement incorrectly states the order of water loss, making it incorrect.

3. **Statement C**: "The process of plasmolysis is usually reversible."
- **Explanation**: Plasmolysis can be reversible or irreversible depending on the type. Concave plasmolysis can be reversed if water is reintroduced, while convex plasmolysis is typically irreversible. The use of "usually" in this statement makes it misleading, thus this statement is also incorrect.

**Conclusion**: Based on the evaluations:
- Statement A is correct.
- Statements B and C are incorrect.

Therefore, the correct option is **A**.