Absorption of Substances by Cells (Diffusion)
- The movement of particles in a liquid or gas from a high conc'n gradient to a low conc'n gradient, until they are balanced.
- The greater the difference in conc'n, the faster the rate of diffusion.
- 2 examples of diffusion through a cell membrane:
- Oxygen required for respiration diffuses into cells.
- CO2 produced by respiration diffuses out of cells.
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Absorption of Substances by Cells (Osmosis)
- The diffusion of water from a dilute conc'n to a higher conc'n through a partially permeable membrane.Until they are balanced.
- 2 examples of osmosis:
- Absorption of water by root hair cells in plants.
- Absorption of water by epithelial cells in the small intestine.
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Absorption of Substances by Cells (Active Transpor
- The process by which cells absorb substances against a conc'n gradient.
- The substance transported attaches to large protein molecules in the cell membrane.
- Energy released through respiration is used to change the shape of the protein.
- This releases the substance through to the other side of the membrane.
- Enables cells to absorb substances from very dilute conc'ns.
- 2 examples:
- Absorption of mineral ions by root hair cells.
- Absorption of glucose by epithelial cells in small intestine.
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Gas Exchange in the Lungs
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