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8.3 Transpiration

Syllabus
0610–2026–2027
Topic
8.3
Level
—

8.3.1—Transpiration as the loss of water

  • Describe transpiration as the loss of water vapour from leaves

8.3.2—Water evaporates from the surfaces

  • State that water evaporates from the surfaces of the mesophyll cells into the air spaces and then diffuses out of the leaves through the stomata as water vapour

8.3.3—Effects of variation of temperature

  • Investigate and describe the effects of variation of temperature and wind speed on transpiration rate

8.3.4—Water vapour loss is related

  • Explain how water vapour loss is related to: the large internal surface area provided by the interconnecting air spaces between mesophyll cells and the size and number of stomata

8.3.5—Mechanism by which water moves upwards

  • Explain the mechanism by which water moves upwards in the xylem in terms of a transpiration pull that draws up a column of water molecules, held together by forces of attraction between water molecules

8.3.6—Effects on the rate of transpiration

  • Explain the effects on the rate of transpiration of varying the following factors: temperature, wind speed and humidity

8.3.7—Why wilting occurs

  • Explain how and why wilting occurs

Objective notes

7 learning objectives
ConceptIGCSE Biology