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Question
Study the experimental setup in the figure and then answer the question that follow.
What is meant by 'semipermeable membrane'?
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Solution
A semipermeable membrane is a membrane which allows the passage of molecules selectively. It allows a solvent such as water molecules to pass through it freely but prevents the passage of the solute (sugar or salt molecules in solution).
RELATED QUESTIONS
What are root hair? Mention the function performed by the root hair.
Concentration of mineral nutrient elements is higher inside the root hairs than in the surrounding soil. How do roots take them in from the soil?
Choose the correct answer:
Absorption of water from soil takes place by __________
Root hairs become flaccid, when fertilizers are added to the moist soil around it. Explain.
A thin strip of epidermal cells from the fleshy scales of an onion bulb was examined in a drop of water, under a microscope. All the epidermal cells looked alike and the figure alongside represents one of them. The thin strip was then transferred to a drop of strong sugar solution and re-examined under the microscope after about five minutes.
(i) Make a sketch of one of the epidermal cells, as it might appear after immersion in a strong sugar solution. Label any two parts which have undergone a change.
(ii) Give the scientific term for the change shown in Q.(i) above.
(iii) What would you do to bring this cell back to its original condition?
(iv) Give the scientific term used for the recovery of the cell as a result of the step taken in Q.(iii) above.
Given below is an experimental demonstration.
(i) Which phenomenon has been demonstrated in the given figure?
(ii) What is the solute and what is solvent in the above experiment?
(iii) Define the phenomenon in Q. (i) above.
(iv) Give one example from your daily life experiences based on this principle.
Column ‘II’ is a list of items related to ideas in Column ‘I’. Match the term in Column ‘II’ with a suitable idea given in Column ‘I’.
| Column I | Column II |
| (i) Diffusion | (a) The exit or flow of water from the cell to the outer environment. |
| (ii) Xylem | (b) The shrinkage of protoplasm when the cell is kept in a hypertonic solution. |
| (iii) Root pressure | (c) The tissue through which water and mineral salts move upward in a plant. |
| (iv) Isotonic solution | (d) Two solutions which have equal osmotic pressure. |
| (v) Exosmosis | (e) The process by which the molecules of perfume spread in the room when the bottle is open. |
| (vi) Osmosis | (f) The process by which roots absorb water from the soil. |
| (vii) Plasmolysis | (g) The pressure by which water rises up to some feet in a lofty tree. |
| (viii) Hypotonic solution | (h) The concentration of the solution when lower than that of the cell sap. |
Multiple Choice Question:
Water will be absorbed by the root hairs when:
Identify labels x, y, z in the given figure of root showing different regions.
