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Diffusion
The movement of molecules from a region of higher concentration to a region of lower concentration, down the concentration gradient.
Resolution
The degree at which a piece of equipment can measure to.
Systematic error
A consistent repeated error.
Random error
Unpredictable errors that are not repeated.
Osmosis
The passive movement of water molecules from an area of higher water potential to an area of lower water potential across a partially permeable membrane.
High water potential
Low concentration of solutes.
Low water potential
High concentration of solutes.
Hypotonic
High water potential
Hypertonic
Low water potential
What happens to the cell mass when the cell has a LWP?
The cell mass will increase because the water is moving into the cell via osmosis.
What happens to the cell mass when the cell has a HWP?
The cell mass will decrease because the water is moving out of the cell via osmosis.
Turgid
Has a larger mass than it did previously.
Flaccid
Has a lower mass than it did previously, is de-hydrated
Plasmolysed
Extremely de-hydrated
What will happen to the mass of a piece of potato, when placed in a strong sugar concentrated solution and left for 24 hours?
The solution is hypertonic to the cell. Therefore, the water inside the potato will move out of the cell via osmosis. The mass of the potato will decrease, becoming flaccid.
Percentage change
(Change in mass/original)*100
Active transport
Substances that are absorbed against the concentration gradient, from low to high concentration.
What does active transport require?
It requires energy.
High SA: Volume ratio
= efficient transfers of substances
Low SA: Volume ratio
= inefficient transfers of substances
Why is SA:V ratio important?
In cells, gases need to diffuse into and out of the cell, if a cell has a large surface area compared to its volume, it will be very efficient when diffusing gases.
Note 
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