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14 Cards in this Set
- Front
- Back
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Define Diffusion |
Diffusion is the - net randon movement of particles - from a region of higher concentration to a region of lower concentration |
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Define Osmosis |
Osmosis is the - net random movement of WATER particles - from a solution of higher WATER POTENTIAL to a solution of lower water potential - through a partially permeable membrane |
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Recall: 4 factors of diffusion |
1. temperature 2. mass of particle 3. concentration gradient (difference in concentration) 4. diffusion distance |
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Relational thinking: how does temperature affect rate of diffusion |
As temperature increases, KINETIC ENERGY of particles increases. This causes particles to move FASTER, leading to increased rate of diffusion |
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Relational thinking: how does mass of particle affect rate of diffusion |
The heavier the particle / as mass of particle increases, the SLOWER they move, leading to decreased rate of diffusion |
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Relational thinking: how does concentration gradient affect rate of diffusion |
The steeper the concentration gradient / the greater the difference in concentration, the faster the rate of diffusion |
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Relational thinking: how does diffusion distance affect rate of diffusion |
The shorter the diffusion distance, the shorter the time taken for diffusion, the higher the rate of diffusion |
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What happens when there is no difference in concentration between 2 regions? |
Diffusion stops BUT the particles will still remain in constant random motion |
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Which process do you frame when you see a cell/potato strip etc. changing in size/mass? |
Frame: OSMOSIS - due to net movement of water particles! Remember: there is no such thing as ....solution/fluid particles! |
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What happens when: ANIMAL cell has a LOWER water potential than surroundings? |
- net movement of water particles from surroundings into cell, via osmosis - animal cell EXPANDS and BURSTS |
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What happens when: PLANT cell has LOWER water potential than surroundings |
- net movement of water particles from surroundings into cell, via osmosis - plant cell expands and becomes TURGID - plant cell does not burst as its cell wall gives it a fixed shape |
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What happens when: ANIMAL cell has HIGHER water potential than surroundings? |
- net movement of water particles from cell into surroundings, via osmosis - animal cells SHRINK and CRENATE |
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What happens when: PLANT cell has HIGHER water potential than surroundings? |
- net movement of water particles from cell into surrounding, via osmosis - plant cell becomes FLACCID and PLASMOLYSED eventually plasmolysed cell: cell wall maintains fixed shape, cytoplasm shrinks and pulls away from cell wall. |
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Comparative Thinking: Describe 2 key differences between diffusion & osmosis |
1. Type of particle: Any type of particle can take part in diffusion but ONLY water particles can take part in osmosis 2. Presence of partially permeable membrane Diffusion can occur with or without a ppm, but osmosis can only occur when a PPM is present (must be present) |
