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Osmosis & Diffusion
Movements of Particles and Concentration Gradients
Question | Answer |
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What is diffusion? | Diffusion is the movement of particles from an area of high concentration to an area of low concentration along a concentration gradient. It is a passive process that does not require energy. |
2 examples of diffusion in living thing? | Oxygen and Carbon Dioxide diffuse in and out of our alveoli and the stomata of peaves. |
What is osmosis? | Osmosis is the movement of water across a semi-permeable membrane from an area of high water concentration to an area of low water concentration. |
What semi-permeable membrane do we use in the lab? | Visking tubing. |
What is osmoregulation? | Ormoregulation is the maintenance of internal water concentration. |
What happens when an animal cell is put in salt water/fresh water. | In fresh water, the water will move into the animal cell by osmosis as it has a lower water concentration. This causes the cell to burst/lyse. In salt water the water is drawn out of the animal cell and it starts to shrink, a process known as crenulation. |
What happens when a plant cell is put in fresh water. | In fresh water the water moves into the plant cell. This causes the cell membrane to push against the cell wall. Creating turgor pressure which keeps the plant upright. |
What happens when a plant cell is put in salt water. | In salt water, water is drawn out of the cell and the cytoplasm shrinks away from the cell wall. This is known as plasmolysis and causes the plant to wilt. |
What is the difference between passive and active transport? | Passive transport occurs along a concentration gradient and does not require energy. Active transport moves against a concentration gradient and requires energy which is usually gotten from respiration. |
How is osmosis used for food preservation? | Adding salt (curing) to meat draws the water out of bacterial cells and prevents is from spoiling the food. Fruits can be preserved by the addition of sugar rather that salt. |