Explain why active transport stops when a cell is deprived of oxygen.

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

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

Root hair cells actively transport nitrate ions from the soil into the cell against the concentration gradient. A student noticed that when the roots of a plant were waterlogged and deprived of oxygen, the uptake of nitrate ions stopped.

Model answer (4 marks)

Active transport needs ATP produced by cellular respiration.
Oxygen is required for aerobic respiration, the main source of ATP.
When roots are waterlogged they become hypoxic, so aerobic respiration stops or is greatly reduced.
With little or no ATP, the carrier proteins cannot change shape and cannot move nitrate ions against their concentration gradient.

Examiner tips

Use the word "ATP" and link it to respiration. Mention oxygen is needed for aerobic respiration. Explain that without ATP the carrier proteins cannot work. Keep answer concise and use the exact terms from the mark scheme.

Common mistakes

Saying the transport stops because of lack of nitrate. Claiming oxygen is needed for all transport. Using vague terms like "energy" without specifying ATP or respiration.

Mark scheme (4 marks)

Active transport requires energy from respiration
Oxygen is needed for (aerobic) respiration
Without oxygen, (aerobic) respiration stops / is reduced, so less / no energy is produced
Without energy, carrier proteins cannot change shape / cannot move nitrate ions against the concentration gradient

Key terms in this question

active transport