Compare active transport with diffusion, stating two differences between the two processes.

Cambridge International IGCSE Biology (0610) — 3.3 Active transport · Compare · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Active transport moves substances against the concentration gradient, whereas diffusion moves substances down the concentration gradient.
Active transport requires energy from respiration (e.g. ATP), whereas diffusion does not require energy from respiration.
Active transport uses carrier proteins to move substances across the membrane, whereas diffusion does not require carrier proteins.

Examiner tips

Use the word ‘differs’ or ‘in contrast’ to show comparison.
Include both processes in each point to show clear contrast.
Mention the key differences: gradient, energy, carrier proteins.
Keep each point short and to the point.

Common mistakes

Stating only one difference or only describing one process. Using vague terms like ‘different’ without specifying the contrast. Omitting the requirement for energy or carrier proteins in active transport.

Mark scheme (4 marks)

Active transport moves substances against the concentration gradient, whereas diffusion moves substances down the concentration gradient.
Active transport requires energy from respiration, whereas diffusion does not require energy from respiration (it uses kinetic energy of the molecules).
Active transport uses carrier proteins to move substances across the membrane, whereas diffusion does not require carrier proteins.
The comparison must be clearly made — the answer must explicitly contrast both processes for the point to gain the mark (e.g. a named difference is stated for both active transport AND diffusion, not just one).

Key terms in this question

active transport · diffusion