Question

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 set up ?

Answer 1

(i) Transpiration

(ii) Transpiration is a process by which water is lost in the form of water vapour from the aerial parts of the plant.

(iii) 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.

(iv). Test tube B is used here as a control. This makes the observation of the change in test tube A easy to observe and infer.