Osmosis
Osmosis is the movement of water across a partially permeable membrane from a dilute solution to a more concentrated one.
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Osmosis is the movement of water across a partially permeable membrane from a dilute solution to a more concentrated one.
- Plant cells become turgid in water
- Animal cells can burst in pure water
- Used to explain wilting
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is Osmosis?
Within Biology, which covers cells, the human body, genetics, evolution, plants and ecosystems: the science of living things, this topic explains Osmosis. Biology topics show how living things work, from the cell up to whole ecosystems, with models you can explore step by step.
Check that you can explain Osmosis in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding Osmosis helps you explain how living things stay alive and respond to their surroundings, which is central to biology exams.
Osmosis in detail
Osmosis is the diffusion of water across a partially permeable membrane from a dilute solution (high water potential) to a concentrated solution (low water potential). The membrane lets water through but not larger solute molecules.
In plants, osmosis makes cells turgid in dilute solutions, which supports the plant, whereas in concentrated solutions the cells lose water and become flaccid or plasmolysed. Animal cells swell and may burst in pure water and shrink in strong solutions. Potato cylinders in different sugar solutions are commonly used to show the effect by measuring changes in mass.
How the interactive helps you understand Osmosis
Watch the cell model in the interactive. Use any sliders or buttons it offers to change the values and see how the cell model responds.
Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Osmosis.
Real-life uses and examples
- Structure a longer answer about Osmosis by moving from definition to example to consequence.
- Explain how Osmosis helps a living thing stay alive, using a plant or animal example.
- Connect Osmosis to health, food and medicine in everyday life.
Common mistakes to avoid
- Listing the steps of a process without saying how one step causes the next.
- Using everyday words, such as “energy” or “bad”, without their scientific meaning.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about Osmosis
What is Osmosis?
Osmosis is the movement of water across a partially permeable membrane from a dilute solution to a more concentrated one.
What are the most important points about Osmosis?
The main points are: Plant cells become turgid in water; Animal cells can burst in pure water; Used to explain wilting.
Why is Osmosis useful?
Understanding Osmosis helps you explain how living things stay alive and respond to their surroundings, which is central to biology exams.
How can I practise Osmosis?
Open the interactive at the top of this page and change the controls one at a time. Predict the result before each change, then take the three-question quiz. A score of two or more marks the topic as complete on this device.
Which topics are related to Osmosis?
Related topics in Biology include Biological Molecules, The Digestive System, Photosynthesis.