Consider the following
i. For a solution at atmospheric pressure `Psi_(w)=Psi_(s)`
ii. `Psi_(w)` (water potential) of a cell is affected by solute potential only
iii. `Psi_(p)` (pressure potential ) is usually positive in xylem during the day which of the statements given above is/are correct?

Options

A. ii & iii
B. I only
C. ii only
D. I, ii and iii

Answer

To solve the question regarding the statements about water potential, we will analyze each statement step by step.

### Step 1: Analyze Statement i
**Statement i:** For a solution at atmospheric pressure, `Psi_(w) = Psi_(s)`.

- Water potential (`Psi_(w)`) is defined as the sum of solute potential (`Psi_(s)`) and pressure potential (`Psi_(p)`).
- At atmospheric pressure, the pressure potential (`Psi_(p)`) is considered to be 0.
- Therefore, the equation simplifies to `Psi_(w) = Psi_(s) + 0`, which means `Psi_(w) = Psi_(s)`.
- **Conclusion:** This statement is **true**.

### Step 2: Analyze Statement ii
**Statement ii:** `Psi_(w)` (water potential) of a cell is affected by solute potential only.

- Water potential is influenced by both solute potential and pressure potential.
- Other factors such as gravity can also affect water potential.
- Therefore, saying that it is affected only by solute potential is incorrect.
- **Conclusion:** This statement is **false**.

### Step 3: Analyze Statement iii
**Statement iii:** `Psi_(p)` (pressure potential) is usually positive in xylem during the day.

- In the xylem, water is transported primarily due to transpiration, which creates a negative pressure (transpirational pull) as water evaporates from the leaves.
- This negative pressure helps pull water upward from the roots to the leaves, indicating that pressure potential is not positive but rather negative during the day.
- **Conclusion:** This statement is **false**.

### Final Conclusion
- Only the first statement is true. Therefore, the correct answer is that only statement i is correct.

### Summary of Correctness of Statements
- Statement i: **True**
- Statement ii: **False**
- Statement iii: **False**