Key definitions

AQA 8461 · 8461 command terms

The definitions AQA marks to the word — say them exactly, not roughly.

Reading mode — read across, know each one cold.

Term	Mark-scheme definition
Diffusion	the net movement of particles from a region of higher concentration to a region of lower concentration (down a concentration gradient).
Osmosis	the diffusion of water from a dilute to a more concentrated solution across a partially permeable membrane.
Active transport	movement of substances from a more dilute to a more concentrated solution (against the gradient), requiring energy from respiration.
Aerobic respiration	glucose + oxygen → carbon dioxide + water (+ energy released); happens in the mitochondria.
Photosynthesis (word equation)	carbon dioxide + water → glucose + oxygen (endothermic; needs light and chlorophyll).
Homeostasis	the regulation of internal conditions to maintain a stable environment in response to internal and external change.
Natural selection	organisms best adapted to their environment survive, reproduce and pass on their alleles.
Biodiversity	the variety of all the different species of organisms on Earth, or within an ecosystem.

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I tutor GCSE Biology from the mark schemes — recall like this is exactly what the first (free) lesson sorts out.