9.1
Transport in the xylem of plants
Essential Idea: Structure and function are correlated in the xylem of plants.
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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 materials that show similarities in structure to plant tissues.
UNDERSTANDINGS:
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Transpiration is the inevitable consequence of gas exchange in the leaf.
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Plants transport water form the roots to the leaves to replace loss from transpiration.
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The cohesive property of water and the structure of the xylem vessels allow transport under tension.
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The adhesive property of water and evaporation generate tension forces in leaf cell walls.
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Active uptake of mineral ions in the roots causes absorption of water by osmosis.
APPLICATIONS & SKILLS:
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Application: Adaptations of plants in deserts and in saline soils for water conservation.
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Application: Models of water transport in xylem using simple apparatus including blotting or filter paper, porous pots, and capillary tubing.
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Skill: Drawing the structure of primary xylem vessels in sections of stems based on microscope images.
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LAB / Skill: Measurement of transpiration rates using potometers.
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Skill: Design an experiment to test hypotheses about the effect of temperature on humidity on transpiration rates.​
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RESOURCES:
