Edexcel IGCSE Biology · Spec 2.15-2.16
Movement of Substances
Diffusion, osmosis and active transport compared — what moves, in which direction, and whether energy is needed.
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Movement of Substances
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Spec 2.15-2.16
What you need to know
- Describe diffusion and osmosis
- Describe active transport
- Compare the three processes
Active recall
Quick check
Answer each question before opening the answer.
Define diffusion, osmosis and active transport.
Diffusion — net movement of particles from high to low concentration. Osmosis — movement of water across a partially permeable membrane from high to low water potential. Active transport — movement from low to high concentration, using energy.
Which of these processes requires energy from respiration?
Active transport.
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