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प्रश्न
Explain the mechanism of closing and opening of the stomata.
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उत्तर
The closing and opening of the stomata depends on the turgidity of the guard cells. Each guard
cell has a thicker wall on the side facing the stoma and a thin wall on the opposite side. Guard cells contain chloroplasts. As a result of the synthesis of glucose during photosynthesis and some other chemical changes, the osmotic pressure of the contents of the guard cells increases and they absorb more water from the neighbouring cells, thus becoming turgid. Due to turgor, the guard cells become more arched outwards and the aperture between them widens, thereby opening the stoma.
At night or when there is shortage of water in the leaf, the guard cells turn flaccid and their inner rigid walls become straight, thus closing the stomatal aperture.
संबंधित प्रश्न
The apparatus arranged alongside signifies an important process.
(i) Name the process.
(ii) Where does this process occur in plants?
(iii) What solution is placed inside the dialysis tubing?
(iv) What happens to the level of the solution in the capillary tube?
The figure shows a diagrammatic representation of the movement of certain substances inside the stem of a certain plant. Write five sentences on whatever you can explain about the processes or the arrangement of structures indicated in the diagram.
Note: - Each sentence must include one or more of the following four words, and each word can be used several times. Xylem, phloem, roots, leaves.
Choose the correct answer:
Swelling of wooden doors during rains is caused by ___________
Given below is the diagram of a cell as seen under the microscope after having been placed in a solution:
(i) What is the technical term used for the state/condition of the cell given above?
(ii) Give the technical term for the solution in which the cell was placed.
(iii) Name the parts numbered 1 to 4.
(iv) Is the cell given above a plant cell or an animal cell ? Give two reasons in support of your answer as evident from the diagram.
(v) What would you do to bring this cell back to its original condition?
Name the following:
Root hairs are the extension of which cells.
Multiple Choice Question:
The most widely accepted theory for ascent of sap is ______.
What is the composition of inner layer of root hair?
Epiphytic plants like ____________ absorb water vapours from air with the help of epiphytic roots having special tissue called velamen.
Look at Figure. Draw another figure of the same set-up as would be observed after a few hours.
What is peculiarity of epiphytic plants like orchids?
