CBSE Class 10 Science 2019 · Paper 31/1/2 · Question 9

Transpiration is the loss of water in the form of vapour from the aerial parts of a plant, mainly through the stomata of its leaves. Experiment: (1) Take a healthy, well-watered potted plant. (2) Cover the soil in the pot with a plastic sheet so that no water evaporates from it. (3) Enclose the leafy shoot in a dry, transparent polythene bag and tie it tightly round the base of the stem. (4) Keep the set-up in bright sunlight for about half an hour. Observation: droplets of water appear on the inner surface of the bag (a similar set-up with the leaves removed stays almost dry). Conclusion: the leaves have given out water vapour, which condensed on the bag; this demonstrates transpiration.