Root hair cells are specialised for the uptake of water and mineral ions from the soil. Describe four features of root hair cells that make them well adapted for this function.

Cambridge International IGCSE Biology (0610) — 8.1 Xylem and phloem · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

1. Root hair cells possess long, thin extensions (root hairs) that greatly increase the surface area available for absorption.
2. The cell wall of root hairs is very thin, which reduces the diffusion distance for water and ions.
3. Water enters root hair cells by osmosis, driven by the higher solute concentration inside the cell.
4. Mineral ions are taken up by active transport mechanisms across the plasma membrane of the root hair cells.

Examiner tips

  • Use the exact terms: 'root hairs', 'thin cell wall', 'osmosis', 'active transport'.
  • Show the four points clearly, each addressing one of the mark scheme items.
  • Keep each point concise and to the point.

Common mistakes

  • Confusing passive diffusion with active transport for mineral ions.
  • Mentioning only surface area without noting the thin wall or osmosis.

Mark scheme (4 marks)

  1. Root hair cells have long hair-like extensions (root hairs) that increase surface area
  2. Water is absorbed by osmosis (into root hair cells)
  3. Mineral ions are absorbed by active transport
  4. Root hair cells have a thin wall, reducing the diffusion distance

Key terms in this question

root hair cells · mineral ions

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