Transpiration

• Transpiration is the loss of water vapour from the stems and leaves of plants
• Light energy converts water in the leaves to vapour, which evaporates from the leaf via stomata
• New water is absorbed from the soil by the roots, creating a difference in pressure between the leaves (low) and roots (high)
• Water will flow, via the xylem, along the pressure gradient to replace the water lost from leaves
• Stomata are pores on the underside of the leaf which facilitate gas exchange
• As photosynthetic gas exchange requires stomata to be open, transpiration will be affected by the level of photosynthesis
• Transpiration is an inevitable consequence of gas exchange in the leaf