Diffusion is the movement of molecules down a concentration gradient from a higher concentration to a lower concentration.
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In which direction do molecules diffuse?
From a high concentration to a low concentration
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What can you use to test for the presence of sugar? What colour does it change from?
A clinistick. blue -> green
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What is used to test for the presence of starch? What colour will the water go?
Iodine, black
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What is the cell membrane? What would you describe it as?
A fluid mosiac/ semi-permeable
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What does selectivly permeable mean?
Only molecules of a specific size can pass through.
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Which 4 molecules diffuse into a cell?
glucose, oxygen, water and amino acids
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Which 3 molecules diffuse out of a cell?
Carbon dioxide, excess water and urea
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What is used as a fake cell membrane in experiments?
Visking tubing
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Which 2 substances make up the cell membrane?
Phospholipids and proteins
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What kind of temperatures damage cell membranes?
High temperatures.
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Phospholipids are damaged by what substance?
Ethanol.
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Define osmosis
Osmosis is the movement of water molecules from a higher water concentration to a lower water concentration through a selectively permeable membrane.
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Does diffusion require energy?
No, it is passive.
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Why is diffusion important?
Because it allows cell to get the molecules they need and get rid of waste.
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What is the name given to diffusion involving only water?
Osmosis.
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In what gradient does osmosis occur?
From a high water concentration to a low WC
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Do plant cells gain or lose water when placed in 100% water?
Gain.
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What is a turgid cell?
A cell in which the vacuole is so full of water that it starts to push against the cell membrane.
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What happens if an animal cell becomes turgid?
An animal cell does not have a vacuole so the water fills up the cell and eventually bursts.
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Why does a plant cell not burst when it becomes turgid?
Because it has a cell wall which prevents the cell from bursting.
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What do you call a plant cell which has lost lots of water?
Plasmolysed.
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What happens to a plasmolysed cell?
The cell membrane peels away from the cell wall and the vacuole shrinks.
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Does active transport require energy?
Yes (ACTIVE)
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Which two substances move by active transport?
Salt and ions.
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Why does active transport require energy?
Because the molecules are transported AGAINST the concentration gradient.
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Does Osmosis require energy?
No it is passive.
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Why are proteins needed for active transport? Why is this active transport?
The proteins present in a cell membrane push molecules through the membrane against the concentration gradient. This is a active transport because it requires energy.
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Other cards in this set
Card 2
Front
In which direction do molecules diffuse?
Back
From a high concentration to a low concentration
Card 3
Front
What can you use to test for the presence of sugar? What colour does it change from?
Back
Card 4
Front
What is used to test for the presence of starch? What colour will the water go?
Back
Card 5
Front
What is the cell membrane? What would you describe it as?
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