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◉ Science·2 min·Updated Mar 14, 2026

What is Osmosis?

Osmosis

Quick Answer

Osmosis is the movement of water molecules through a semi-permeable membrane from an area of low concentration of solutes to an area of high concentration of solutes. This process helps to balance solute concentrations on both sides of the membrane. It is essential for many biological processes.

Overview

Osmosis is a fundamental process in chemistry and biology that involves the movement of water across a semi-permeable membrane. This membrane allows water molecules to pass through while blocking certain solute particles. As water moves from an area with fewer solutes to an area with more solutes, it helps to equalize the concentration of substances on both sides of the membrane, which is crucial for maintaining cellular health and function. In practical terms, osmosis can be observed in everyday life, such as when a raisin is placed in water. The water moves into the raisin, causing it to swell as the concentration of solutes inside the raisin is higher than that of the surrounding water. This example illustrates how osmosis can affect living cells and is a key concept in understanding how plants absorb water and nutrients from the soil. Understanding osmosis is important in various fields, including medicine and agriculture. In medicine, it plays a role in how fluids are administered to patients, ensuring that cells maintain their proper shape and function. In agriculture, knowledge of osmosis helps farmers manage irrigation and understand how plants take up water, which is vital for crop growth.

Frequently Asked Questions

A semi-permeable membrane is a barrier that allows certain molecules, like water, to pass through while blocking others, such as larger solute particles. This property is crucial for processes like osmosis, where water moves to balance solute concentrations.
In plant cells, osmosis helps maintain turgor pressure, which keeps the cells firm and supports the plant's structure. When water enters the cells through osmosis, it fills the vacuoles, pushing against the cell wall and preventing wilting.
While osmosis primarily involves water, the concept can apply to other solvents as well. However, the most common and well-known examples involve water due to its unique properties and role in biological systems.