Biology
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.
Roots Absorption
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Answer
(a) Osmosis
(b) Osmosis is the movement of water molecules from their region of higher concentration (dilute solution or with a lower solute concentration) to their region of lower concentration (concentrated solution or with a higher solute concentration) through a semi permeable membrane.
(c) After an hour or so, the level of sugar solution in the thistle funnel will rise and the level of water in the beaker will drop slightly.
(d) As a control, take another thistle funnel with plain water filled in it and suspend it in another beaker also containing water. Again mark the level on its stem.
(e) The corresponding parts are mentioned below:
- Concentrated sugar solution → Cell sap (of higher concentration than that of the surrounding water) within the root hair.
- Parchment paper → Cell membrane of root hair.
- Water in the beaker → Water in soil.
(f) The other substance that can be used instead of parchment paper in the above experiment is cellophane paper or animal bladder.
(g) Advantages of the osmosis process are —
- It controls the absorption of water by root hairs from the soil.
- It controls opening and closing of stomata during transpiration through its regulation of the turgidity of guard cells.
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Related Questions
A leaf cell of a water plant was placed in a liquid other than pond water. After sometime, it assumed a shape as shown below:
(a) Give the term for the state of the cell it has acquired.
(b) Name the structure which acts as a selectively permeable membrane.
(c) Comment on the nature (tonicity) of the liquid surrounding the cell.
(d) Name any one feature of this plant cell which is not present in an animal cell.
(e) Redraw in the space provided, the diagram of the cell if it is soon placed in ordinary water for some time.
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).
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 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.