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Study the diagram given below and answer the questions that follow:

Study the diagram and answer the questions that follow. Name the process being studied in experiment. Explain the process. Why is oil placed over water? What do we observe with regard to the level of water when this set up is placed in bright sunlight, humid conditions, windy day? Mention any three adaptations found in the roots of the plant which enable them to carry out the process mentioned. Absorption by Roots, Concise Biology Solutions ICSE Class 10.

(a) Name the process being studied in the above experiment.

(b) Explain the process mentioned in (a) above

(c) Why is oil placed over water?

(d) What do we observe with regard to the level of water when this set up is placed in (1) bright sunlight (2) humid conditions (3) windy day?

(e) Mention any three adaptations found in the roots of the plant which enable them to carry out the process mentioned in (a).

Roots Absorption

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Answer

(a) The process of absorption of water by plant roots through osmosis is being studied here.

(b) Absorption of water by the root is by means of root hairs. A root hair contains cell sap which has a higher concentration of salts as compared to the outside soil water. This difference sets of osmosis and the outside soil water diffuses into the root hair. From the cell bearing root hair, water continues to pass to adjoining cells one after another to finally enter the xylem vessels. The turgidity acquired by the cells in the process also helps to push the water upwards through the xylem vessels.

(c) The surface of water is covered with oil to prevent any loss of water by evaporation.

(d) Roots absorb water and hence, the level of water in set up A falls down. Since the surface of water was covered with oil, there will be no effect of factors such as bright sunlight, humid conditions and windy day on the given set up. Hence, the level of water.

(d) Below are the observations with regard to the level of water for the different situations:

  1. Bright Sunlight — When this set up is placed in bright sunlight, the water level in the test tube is seen to be less when compare to its initial marking as the rate of transpiration is very high.
  2. Humid Conditions — When this set up is placed in humid conditions, the water level in the test tube decreases from its initial mark, but at a very slow rate as the rate of transpiration is reduced.
  3. Windy Day — When this set up is placed in windy day the rate of transpiration highly increases thus the level of the water in the test tube is seen to decrease fast from its initial marking.

(e) Adaptations in plants to foster the process of absorption of water by plant roots:

  1. Large surface area provided by rootlets and root hairs.
  2. Root hairs contain cell sap at a higher concentration than that of the surrounding water
  3. Root hairs with thin walls.

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