Describe how active transport moves ions into root hair cells from the soil.

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

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

Plants absorb mineral ions such as nitrates from the soil through root hair cells. The concentration of these ions inside the root hair cell is already greater than the concentration in the surrounding soil.

Model answer (4 marks)

Active transport moves ions against the concentration gradient, from the low concentration in the soil to the high concentration inside the root hair cell.
Energy from cellular respiration (ATP) is required.
Carrier proteins in the cell membrane bind the ion.
The carrier changes shape, translocates the ion across the membrane and releases it on the other side.

Examiner tips

Use the phrase "against the concentration gradient". Mention ATP or respiration as the energy source. Identify carrier proteins and their shape change. Keep answer concise and use exam terminology.

Common mistakes

Confusing passive diffusion with active transport. Failing to mention ATP or energy. Omitting the carrier protein or its shape change.

Mark scheme (4 marks)

Active transport moves ions against the concentration gradient (from low to high concentration)
Energy from respiration is required / used
Carrier proteins in the cell membrane are involved
The carrier protein changes shape to move the ion through the membrane and releases it on the other side

Key terms in this question

active transport