Describe the pathway taken by water as it moves from the soil into the air spaces inside a leaf, naming the structures involved.

Cambridge International IGCSE Biology (0610) — 8.3 Transpiration · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Water enters the plant through root hair cells by osmosis.
Water moves through the root cortex cells (by osmosis) to reach the xylem.
Water is carried up the stem to the leaves via the xylem.
Water evaporates from the surface of mesophyll cells into the air spaces inside the leaf.

Examiner tips

Use the exact sequence of structures: root hair cells → root cortex cells → xylem → mesophyll cells → leaf air spaces.
Show the transport mechanism (osmosis, xylem flow) and the final evaporation step.
Keep the answer concise – one sentence per point for 4 marks.

Common mistakes

Omitting the root cortex cells or the xylem as transport pathways.
Confusing the direction of water movement (e.g., saying it moves downwards).
Using vague terms like ‘through the plant’ instead of naming specific structures.

Mark scheme (4 marks)

Water enters the plant through root hair cells by osmosis
Water passes through the root cortex cells (by osmosis) before reaching the xylem
Water is transported up the stem to the leaves through the xylem
Water evaporates from the surface of mesophyll cells into the air spaces inside the leaf

Key terms in this question

air spaces