Chapter 11 - Transport in Plants

companion cell

Specialised cell lying next to a sieve tube in the phloem and controlling its activities.

cuticle

Thin layer of waxy material covering the epidermis cells of a plant.

flaccid

Condition in a plant cell which has lost internal pressure, so that the cytoplasm no longer pushes against the cell wall.

guard cells

Pair of specialised cells surrounding a stoma in the epidermis of a leaf. They change shape to open or close the stoma.

lignin

Woody material present in the cell walls of some plant cells, such as xylem vessels. Provides strength and makes the walls impermeable to water.

phloem

Plant transport tissue responsible for moving the products of photosynthesis from the leaves to other parts of the plant.

plasmolysed

Condition of a plant cell that has lost water by osmosis, resulting in the cell contents shrinking and the cell membrane and cytoplasm pulling away from the cell wall.

root hairs

Specialised cells on the surface of a root that take up water and mineral ions from the soil.

sieve plate

Specialised end wall of sieve tube, with holes allowing connections between one cell and the next.

sieve tube

Cell found in phloem, consisting of tube transporting the products of photosynthesis.

stomata (singular = stoma)

Pores in the epidermis of a leaf.

transpiration stream

Passage of water and minerals through the roots, stem and leaves of a plant.

transpiration

Loss of water vapour from the leaves of plants.

turgid

Description of a plant cell with a high internal pressure, so that the cytoplasm pushes against the cell wall.

turgor

Condition of a plant when its cells are turgid.

vascular bundle

Xylem and phloem grouped together in a stem or root.

water potential

Measure of the ability of water molecules to move in a solution. Pure water has the highest water potential.

wilt

Changes taking place in a plant when its cells lose too much water and become flaccid. The leaves droop and collapse.

xylem

Transport tissue carrying water and minerals up through a plant from the roots.