Q. 75.0( 1 Vote )
Study the diagram
(a) The process being studied in the above experiment is transpiration of water.
(b) Transpiration is defined as the loss of water through evaporation from the aerial parts (stem and leaves) of the plant.
(c) A layer of oil is placed over the water to ensure that no loss of water takes place through direct evaporation from the water present in the test tube.
(d) When the experimental setup is placed in
1. Bright sunlight: In bright sunlight, the rate of transpiration highly increases thus the level of the water level in the test tube is seen to decrease fast from its initial marking.
2. Humid conditions: In humid condition, the rate of transpiration is reduced and thus level of water in the test tube decreases from its initial mark, but at a very slow rate.
3. Windy day: On a windy day the rate of transpiration highly increases thus the level of the water level in the test tube is seen to decrease fast from its initial marking.
(e) To foster the process of transpiration the three adaptations found in plants are:
i. Narrow leaves to reduce the surface area for transpiration.
ii. Loss of leaves, that is, leaves are completely absent or changed into spines, such as in cacti.
iii. Presence of a thick cuticular (wax) layer present on the surface of the leaves.
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