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GCSE Biology · key term
A strengthening substance deposited in xylem vessel walls.
Used by AQA, Edexcel and OCR
Specification 4.1.1.3, 4.2.3.2 · Paper 1
A strengthening substance in the walls of xylem vessels.
Revise: Cell SpecialisationLignin strengthens their walls, helping the vessels resist collapse and support the plant.
A strong substance deposited in xylem walls that strengthens the tubes and helps prevent them from collapsing.
Specification 6.8 · Paper 2
A strengthening substance deposited in xylem cell walls that helps the vessels resist collapse and support the plant.
Revise: Xylem and PhloemThe vessel walls are thickened with lignin. This makes them strong enough to resist collapse as water is pulled upwards through the plant. The strengthened xylem also helps support the plant.
Specification B2.2h · Paper 1 (Foundation), Paper 3 (Higher)
A strong substance deposited in some plant cell walls, including xylem vessel walls, which strengthens the tissue.
Revise: Xylem and phloemThe walls are thickened with lignin, making the vessels strong. This helps the tubes resist collapse as water is drawn upwards and also gives mechanical support to the plant.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
Revise: Xylem and PhloemIts vessels are formed from cells that have died and lost their end walls. This leaves long, hollow tubes with little to obstruct the flow of water. Their walls contain lignin, which strengthens them, helps prevent them from collapsing and supports the plant.
Link each structural feature to its function: a hollow xylem vessel allows water to flow, while lignin strengthens its walls.
Link each structural feature to what it does: for example, a hollow xylem vessel provides a continuous route for water, while lignin strengthens its wall.
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