Biology
The figure given below represents an experimental set up with a weighing machine to demonstrate a particular process in plants. The experimental set up was placed in bright sunlight. Study the diagram and answer the following questions.
(a) Name the process intended for study.
(b) Define the above mentioned process.
(c) When the weight of the test tubes A and B is taken before and after the experiment, what change is observed? Justify.
(d) What is the purpose of keeping the test tube B in the experimental setup?
(e) What is the purpose of putting oil in the test tube?
Transpiration
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Answer
(a) Transpiration
(b) Transpiration is a process by which water is lost in the form of water vapour from aerial parts of the plant.
(c) Weight of test tube A before the experiment was more than its weight after the experiment. This is because water from test tube A has evaporated due to transpiration.
Weight of test tube B remains the same before and after the experiment, because no loss of water occurs in test tube B.
(d) Test tube B is used here as a control. This makes the observation of the change in test tube A easy.
(e) The purpose of putting oil in the test tube is to prevent loss of water from the test tube by evaporation.
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