Term
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Definition
1- Phospholipids (in a bilayer).
2- Proteins. These can be on the inner or outer surface of the membrane or embedded within the membrane surface. These proteins can help move molecules into or out of the cell.
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Term
| 2-Property of the cell membrane |
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Definition
| It is selectively permeable (only let molecules smaller than a certain size go through) |
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Term
| 3-Characteristics of passive transport |
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Definition
| Passive transport happens down a concentration gradient and does not require energy. |
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Term
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Definition
| The molecules which form the cell membrane move constantly with respect to each other. |
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Term
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Definition
| Diffusion in cells is the movement of molecules down a concentration gradient, from an area of high concentration to an area of low concentration |
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Term
| 6-Importance of diffusion |
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Definition
It is how gases (CO2, O2) and some other substances, e.g. water, glucose, urea and amino acids move in and out of cells.O2 and glucose are needed by animal cells for respiration.
Water and CO2 are needed by plants for photosynthesis. |
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Term
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Definition
| Osmosis is the movement of water molecules down a concentration gradient through a selectively permeable membrane. |
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Term
| 8-Effect of osmosis on animal cells |
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Definition
Water loss: cells shrink.
Water gain: cells burst. |
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Term
| 9-Effect of osmosis on plant cells |
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Definition
Water loss: cells plasmolysed (cell shrinks away from the cell wall, cell wall caves in)
Water gain: cells turgid (swollen cell which does not burst due to the support of the cell wall). |
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Term
| 10-In experiments, the diffusion of substances is usually demonstrated by… |
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Definition
| A reagent changing colour. |
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Term
| 11-In experiments, osmosis is usually demonstrated by… |
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Definition
| A change in mass of a piece of potato or a model cell or the change of volume of a solution (visible on a graduated tube). |
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Term
| 12-Define active transport |
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Definition
| Transport against the concentration gradient. |
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Term
| 13-Requirements for active transport |
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Definition
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Term
| 14-Examples of molecules and organisms using active transport |
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Definition
| Transport of sodium and potassium in nerve cells, or iodine in seaweeds. |
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