Define water potential and solute potential.

Explanation

**Step-by-Step Solution:**

1. **Definition of Water Potential:**
- Water potential (Ψw) is defined as the measure of the free energy of water per unit volume. It indicates the potential energy of water in a system compared to pure water.
- The unit of water potential is typically expressed in bars or Pascals (Pa).
- The water potential of pure water at atmospheric pressure is considered to be zero (Ψw = 0).

2. **Understanding the Components of Water Potential:**
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