Year 7 - Science
Diffusion through the cell membrane
Diffusion
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit explores diffusion's role in material movement in and between cells and involves making predictions, observations and measurements with various methods.
Lesson Summary
You will learn to explain why some substances can diffuse through the cell membrane and others cannot.
Key Notes
- All substances, including the cell cytoplasm and substances within it, are made up of particles.
- Particles of some substances diffuse into and out of a cell by moving through small holes in the cell membrane.
- The particles that make up some substances are too big to diffuse through the holes in the cell membrane.
- The cell membrane is selectively-permeable because only some substances can diffuse through it.
- The net movement of particles through a cell membrane is down a concentration gradient.
Vocabulary To Learn
- cell membrane: All cells are surrounded by a membrane that controls what can enter and leave the cell.
- particles: All substances are made up of particles that are too small for us to see.
- diffusion: Diffusion is the net movement of particles of a substance down a concentration gradient.
- selectively-permeable: A material is selectively-permeable if some substances can move through it but others cannot.
- net movement: Net movement is the overall movement of particles from one area to another.
Common Mistakes To Avoid
- Thinking that all, or no, substances can diffuse through the cell membrane. Thinking that cells choose to take in particular substances, or that cells breathe or suck in substances such as oxygen.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
All substances, including the cell cytoplasm and substances within it, are made up of particles. Particles of some substances diffuse into and out of a cell by moving through small holes in the cell membrane.
2. Define this scientific word and use it in context. 'cell membrane'
All cells are surrounded by a membrane that controls what can enter and leave the cell. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Thinking that all, or no, substances can diffuse through the cell membrane. Thinking that cells choose to take in particular substances, or that cells breathe or suck in substances such as oxygen. Correction: The lesson explores the idea that particles of some, but not all, substances are small enough to diffuse through holes in the selectively-permeable cell membrane.
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