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प्रश्न
How is root hair adapted for the absorption of water from the soil?
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उत्तर
The main root with its many branches form a network in the soil. The root hairs get entangled in the soil particles and remain in close contact with the capillary water surrounding the soil particles. The epidermal cells of root hairs have vacuoles which contain cell sap. Generally, the cell sap is more concentrated than the soil solution. As a result the water enters inside the root hair cells by endosmosis. This water dilutes the epidermal cell sap solution. Then water enters into the cortical cells by osmosis and reaches the endodermal cells and then pericycle cells. From this layer water then enters in the xylem tissue. In this way, the water is absorbed and translocated up to xylem of the root by osmosis.
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संबंधित प्रश्न
Match the items in column I with those in column II
| Column I | Column II | ||
| (a) | Xylem | (i) | semi - permeable |
| (b) | Phloem | (ii) | permeable |
| (c) | Cell membrane | (iii) | downward flow of sap |
| (d) | Root pressure | (iv) | upward flow of water |
| (e) | Cell wall | (v) | guttation |
Explain the mechanism of closing and opening of the stomata.
Three plants (a), (b) and (c) were placed in beakers containing coloured water. The water in each beaker was covered with a layer of oil. The leaves were removed from plant (b), while plant (c) was exposed to strong light.
(i) In which plant, (a), (b) or (c) would the water move up the fastest?
(ii) In which plant (a), (b) or (c), would the water move up slowly?
(iii) Why was the water covered with a layer of oil?
(iv) What is being investigated by this experiment?
Choose the correct answer:
Process of ascent of sap in plants occurs ___________
Choose the correct answer:
Absorption of water from soil takes place by __________
Choose the correct answer:
In ascent of sap water reaches upwards ____________
Study the experimental setup in the figure and then answer the question that follow.
What is meant by 'semipermeable membrane'?
Multiple Choice Question:
In soil, water available for absorption by root is ______.
Root hair is ________ extension of epiblema cells.
Minerals cannot be passively absorbed by the roots.
