---
title: "Water Potential — AP Biology Definition & Exam Guide"
description: "Water potential (Ψ) predicts which way water moves by osmosis. Learn the Ψ = Ψs + Ψp formula, how it's tested in Unit 2, and why MPa values matter."
canonical: "https://fiveable.me/ap-bio/key-terms/water-potential"
type: "key-term"
subject: "AP Biology"
---

# Water Potential — AP Biology Definition & Exam Guide

## Definition

Water potential refers to water's potential energy or its tendency to move from areas of high concentration to low concentration through osmosis.

## Related Study Guides

- [2.8 Mechanisms of Transport](/ap-bio/unit-2/tonicity-osmoregulation/study-guide/CCENUydXNVb7K4P7ikp7)

## Review

### Related Terms

- [Osmosis](/ap-bio/key-terms/osmosis): This is the process by which water moves across a semi-permeable membrane from areas of low solute concentration to areas of high solute concentration.
- [Solute Potential](/ap-bio/key-terms/solute-potential): Also known as osmotic potential, it's one component of water potential and refers to how much solutes affect where water will flow.
- Pressure Potential: This is another component of water potential that takes into account physical pressure on a solution, which can impact where water flows.