9.1 Transport in Xylem of Plants

Understandings:

Transpiration is the inevitable consequence of gas exchange in the leaf.
Plants transport water from the roots to the leaves to replace losses from transpiration.
The cohesive property of water and the structure of the xylem vessels allow transport under tension.
The adhesive property of water and evaporation generate tension forces in leaf cell walls.
Active uptake of mineral ions in the roots causes absorption of water by osmosis

Applications

Adaptations of plants in deserts and in saline soils for water conservation.
Models of water transport in xylem using simple apparatus including blotting or filter paper, porous pots and capillary tubing.

Skills

Drawing the structure of primary xylem vessels in sections of stems based on microscope images.
Measurement of transpiration rates using photometers. (Practical 7)
Design of an experiment to test hypothesis about the effects of temperatures or humidity on transpiration rates.

Nature of Science

Use models as representations of the real world-mechanisms involved in water transport in the xylem can be investigated using apparatus and material that show similarities in structure to plant tissues.

Powerpoints

Homeworks

9.1 Transport in the Xylem of Plants