Transport in the xylem of plants

Topic 9.1

Essential idea: Structure and function are correlated in the xylem of plants.

Understandings

9.1.U1 Transpiration is the inevitable consequence of gas exchange in the leaf.

Gas exchange leads to water loss due to transpiration

9.1.U2 Plants transport water from the roots to the leaves to replace losses from transpiration

Transpiration stream from roots to leaves

9.1.U3 The cohesive property water and the structure xylem vessels allow transport under tension

Cohesive property of water explained

9.1.U4 The adhesive property of water and evaporation generate tension forces in leaf cell walls

Xylem transport and adhesive property

9.1.U5 Active uptake of mineral ions in the roots causes absorption of water by osmosis

Mineral uptake in roots and water uptake by osmosis

Applications

9.1.A1 Adaptations of plants in deserts and in saline soils for water conservation

Adaptations of plants in desert and saline soils

9.1.A2 Models of water transport in xylem using simple apparatus including blotting or filter paper, porous pots and capillary tubing

Using models in water transport in xylem

Skills

9.1.S1 Drawing the structure of primary xylem vessels in sections of stems based on microscope images

Stem Labelled

9.1.S2 Measuring transpirations rates using potometers

Diagram of a potometer

9.1.S3 Design of an experiment to test hypotheses about the effect of temperature or humidity on transpiration rates

Go to Internal Assessment: Design
Go to Internal Assessment: Data Collection and Processing
Go to Internal Assessment: Conclusion and Evaluation
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