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GCSE Biology · key term
The change in a measured quantity divided by the time taken for that change.
Used by Edexcel and OCR
Specification 6.13, 9.19B · Paper 2
The amount of change divided by the time taken for that change.
Revise: Rate Calculations for TranspirationMost water taken up replaces water lost by transpiration, so uptake rate is a useful estimate of transpiration rate. Some absorbed water is retained or used by the plant, which is why the two rates are not necessarily identical.
Specification B2.2j · Paper 1 (Foundation), Paper 3 (Higher)
Revise: PotometerA potometer measures the rate of water uptake by a leafy shoot.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
Revise: Rate Calculations and GraphsA rate tells us how much change happens in a particular time. The rate of photosynthesis cannot be measured directly, so an investigation measures a quantity linked to it. Pondweed may be used to count the oxygen bubbles released or to collect and measure the volume of oxygen produced.
The amount of a measurable change occurring per unit time.
Convert measurements to consistent units before calculating a rate.
Write the rate equation before substituting values, and include a compound unit such as g/day or pH units/min.
For mass remaining, a negative gradient means the mass is decreasing. If asked for the rate of decay, give the magnitude unless the question specifically asks for the signed gradient.
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