A muscle cell and a root hair cell are both specialised cells found in living organisms. Explain how the structure of a root hair cell is related to its function, and describe how cell differentiation allows multicellular organisms to become more efficient.

OCR A-Level Biology B — Advancing Biology (H422) — 2.1 Cell structure · Explain · 5 marks · View as Markdown

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

Stem cells are unspecialised cells that can differentiate into a range of different cell types. Once differentiated, cells such as root hair cells and muscle cells are highly adapted for their roles.

Model answer (5 marks)

A root hair cell has a very long, thin shape that gives it a large surface area relative to its volume. The large surface area increases the rate of uptake of water and minerals from the soil, which is its main function.

Cell differentiation is the process by which unspecialised stem cells become specialised cells. Because specialised cells are adapted to particular tasks, they can carry out their functions more effectively and efficiently than unspecialised cells. For example, muscle cells are specialised for contraction and relaxation, allowing rapid movement of the body.

Examiner tips

  • Use the exact terms ‘large surface area’ and ‘rate of uptake’ for the root hair cell; link structure to function. Mention that differentiation produces specialised cells. Give a clear example of a specialised cell and its adaptation. Keep the answer concise – 5 marks are enough for a short paragraph.

Common mistakes

  • Writing that root hair cells are ‘long’ without mentioning surface area. Forgetting to explain how differentiation improves efficiency. Using vague phrases like ‘good at their job’ instead of specific adaptations.

Mark scheme (5 marks)

  1. Root hair cells have a large surface area
  2. Large surface area increases the rate of uptake of water and minerals from the soil
  3. Cell differentiation is the production of specialised cells (from unspecialised/stem cells)
  4. Specialised cells can carry out their function more effectively / efficiently than unspecialised cells
  5. Named example of how a specialised cell is adapted, e.g. muscle cells can contract/relax to cause movement, OR nerve cells transmit electrical impulses, OR red blood cells have a biconcave shape to increase surface area for oxygen exchange

Key terms in this question

cell differentiation · specialised cells · multicellular organism

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