Osmosis

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What is a solute?
A substance dissolved in a solvent
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What is water potential (ψ)?
The measure of water molecules compared to solutes which is measured as the pressure exerted by water molecules colliding with a membrane or a container
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How is water potential effected?
The more solute in the water, the more negative the water potential is
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What is water potential measured in?
Kilopascals (KPa)
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What water potential does pure water have?
0KPa, the presence of a solute lowers ψ below 0
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When solutions with different ψ are separated by a partially permeable membrane, what happens?
The water molecules can move across the membrane but the solutes cannot, therefore the water molecules will have a net movement to the solution with a lower water potential down a water potential gradient, until an equilibrium is reached
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What is hydrostatic pressure?
The pressure erected by water in an enclosed system
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What happens to an animal cell when placed in a hypotonic solution?
Cytolysis- The hypotonic solution has a greater water potential than the cell and so the net movement of water is into the cell, causing the cell to swell and eventually burst, due to the membrane not being able to with stand the hydrostatic pressure
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What happens to an animal cell when placed in a isotonic solution?
Nothing- The isotonic solution has the same water potential as the cell cytoplasm so water constantly moves in and out but at equal rates
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What happens to an animal cell when placed in a hypertonic solution?
Crenation- The hypertonic solution has a lower water potential than the cell cytoplasm, the water moves out of the cell and the cell shrinks, with the cell membrane puckering
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What happens to a plant cell when placed into a hypotonic solution?
Turgor- (ideal for plants) Water moves into cell and hydrostatic pressure increases, pushing the cell membrane against the cell wall making the cell turgid
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What happens to a plant cell if you place it in a isotonic solution?
The water equally moves in and out, hydrostatic pressure is lower so the membrane pulls away slightly from the cell wall
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What happens to a plant cell if you place it in a hypertonic solution?
Plamolysis- Water moves out of the cell and the cell wall pulls away from the cell wall as the contents shrink, the cell is plasmolysed
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Other cards in this set

Card 2

Front

What is water potential (ψ)?

Back

The measure of water molecules compared to solutes which is measured as the pressure exerted by water molecules colliding with a membrane or a container

Card 3

Front

How is water potential effected?

Back

Preview of the front of card 3

Card 4

Front

What is water potential measured in?

Back

Preview of the front of card 4

Card 5

Front

What water potential does pure water have?

Back

Preview of the front of card 5
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