Biology
Study the diagram given below and answer the questions that follow:
(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
ICSE
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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:
- 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.
- 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.
- 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:
- Large surface area provided by rootlets and root hairs.
- Root hairs contain cell sap at a higher concentration than that of the surrounding water
- Root hairs with thin walls.
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Related Questions
Three cylinders of potato were carefully dried on a blotting paper and weighed. Each piece weighed 3 grams. Each one was placed in the beaker as shown below:
Answer the following questions:
(a) After 48 hours, which potato cylinder would be the heaviest?
(b) The movement of which substance is mainly responsible for the weight change in the potato cylinders?
(c) Name and define the process which is responsible for the movement of substance mentioned in answer (b).
(d) Write specific names of the processes which occur in beakers B and C [kinds of processes defined in answer (c)].
(e) Would there be any difference in the weight of the potato cylinder in beaker A after 48 hours? Give reason.
The diagram given below represents an experimental set-up to demonstrate a certain process. Study the same and answer the questions that follow:
(a) Name the process.
(b) Define the above named process.
(c) What would you observe in the experimental set-up after an hour or so?
(d) What control experiment can be set up for comparison?
(e) Keeping in mind the root-hair, cell and its surroundings, name the parts that correspond to (1) concentrated sugar solution (2) parchment paper and (3) water in the beaker.
(f) Name any other material that can be used instead of parchment paper in the above experiment.
(g) Mention any two advantages of the process to the plants.
The figure given below is a diagrammatic representation of a part of the cross-section of the root in the root hair zone. Study the same and then answer the questions that follow:
(a) The parts labelled as 1, 2, 3 and 4 are :
- Root hair, Xylem vessel, Soil particles, Cortex respectively.
- Xylem vessel, Soil particles, Root hair, Cortex respectively.
- Root hair, Xylem vessel, Cortex, Soil particles respectively.
- Cortex, Soil particles, Xylem vessel, Root hair respectively.
(b) The process that enables the passage of water from soil into the root hair is :
- Diffusion
- Active transport
- Osmosis
- Passive absorption
(c) The kind of force which exists between a liquid and any surface is called as :
- Cohesive force
- Adhesive force
- Capillarity
- Suction force
(d) The kind of force between the same kind of liquid molecules is :
- Capillary force
- Transpirational pull
- Adhesive force
- Cohesive force
(e) Sometimes exudation of water occurs from the margin of the leaves in early morning or night. It is termed as :
- Transpiration
- Bleeding
- Guttation
- Osmosis
The diagram below represents a layer of epidermal cells showing a fully grown root hair. Study the diagram and answer the questions that follow:
(a) Name the parts labelled A, B, C and D.
(b) The root hair cell is in a turgid state. Name and explain the process that caused this state.
(c) Mention one distinct difference between the parts labelled A and B.
(d) Draw a diagram of the above root hair cell as it would appear when a concentrated solution of fertilizers is added near it.