Osmostic potential is

Options

A. Positive
B. Negative
C. Always zero
D. Greater than one

Answer

**Step-by-Step Solution:**

1. **Understanding Osmotic Potential**: Osmotic potential, also known as solute potential, is a measure of the tendency of water to move into a solution due to the presence of solute. It is an important concept in understanding how water moves in and out of plant cells.

2. **Water Potential Basics**: Water potential (Ψ) is a measure that combines the effects of solute concentration and pressure. The formula for water potential is:
\[ Ψ = Ψ_s + Ψ_p \]
where Ψ_s is the osmotic potential and Ψ_p is the pressure potential.

3. **Initial Value of Water Potential**: In pure water, the initial water potential is considered to be zero (Ψ = 0). As solutes are added to the water, the water potential decreases.

4. **Effect of Solute on Water Potential**: When solutes are added, they lower the water potential because the presence of solutes reduces the ability of water to move freely. Therefore, the osmotic potential (Ψ_s) becomes negative as solute concentration increases.

5. **Conclusion**: Since the osmotic potential is a measure of the solute concentration in a solution, it is typically negative. This is because the addition of solute decreases the water potential from its initial value of zero.

Thus, the correct answer to the question "Osmotic potential is" is that it is **negative**.

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