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GCSE Biology · key term
The difference in the concentration of a substance between two regions.
Used by AQA, Edexcel and OCR
Specification 4.1.3.1, 4.1.3.2, 4.1.3.3 · Paper 1
Revise: Principles and Factors of DiffusionThe overall result is movement down the concentration gradient.
The difference between two concentrations; in osmosis, it helps determine the direction of net water movement.
A difference in the concentration of a substance between two regions.
Specification 1.15, 6.12, 8.3, 8.4B · Paper 1, Paper 2
A difference in the concentration of a substance between two regions.
Revise: Transport in CellsA difference in concentration between two regions is called a concentration gradient. This gradient determines the direction of diffusion and osmosis, while active transport allows cells to move substances in the opposite direction.
The difference in the concentration of a substance between two regions; a steeper difference causes faster net diffusion.
The difference in a substance’s concentration between two places, which drives its net diffusion from higher to lower concentration.
The difference in a substance’s concentration between two regions; a steeper gradient means a greater difference over the distance between them.
Specification B2.1a, B2.2f, B2.2i · Paper 1 (Foundation), Paper 3 (Higher)
Revise: Transport in cellsDiffusion is therefore the net movement of particles from a region of higher concentration to a region of lower concentration. This is movement down the concentration gradient. A concentration gradient is simply a difference in concentration between two regions.
A difference in the concentration of a substance between two regions.
The difference in the concentration of a substance between two regions; a steeper gradient produces faster net diffusion.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
A difference in the concentration of a substance between two regions.
Revise: Diffusion, Osmosis and Active TransportIf there is more of it in one region than another, there is a concentration gradient. Particles move randomly, but more leave the crowded region than return to it. This overall movement from higher to lower concentration is diffusion.
A difference in the concentration of a substance between two places.
Do not say that concentration itself is the concentration gradient. The gradient is the difference in concentration between two regions.
For a definition of active transport, include all three ideas: movement from lower to higher concentration, against the concentration gradient, and a requirement for energy from respiration.
Do not say that active transport is a type of diffusion. Diffusion is passive and moves substances down a concentration gradient; active transport requires energy and moves substances against it.
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