Transpiration

What the syllabus asks of you

• Describe transpiration as the loss of water vapour from leaves
• 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 4 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 5 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
• Investigate and describe the effects of variation 6 Explain the effects on the rate of transpiration of of temperature and wind speed on transpiration varying the following factors: temperature, wind rate speed and humidity 7 Explain how and why wilting occurs