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प्रश्न
Leaves of the sensitive plant wilt and droop down on a slight touch. What mechanism brings about this change?
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उत्तर
Leaves of the sensitive plant wilt and droop down on a slight touch due to turgor movement. Petiole of sensitive plant is held up by turgid pulvinus tissue. The stimulus of touch leads to loss of turgor at the base of the leaflets and at the base of the petioles i.e. pulvinus. The cells of the lower side of pulvinus lose water and the petiole collapses. This causes the wilting and drooping of the leaves
संबंधित प्रश्न
(a) Mention whether the following statement is true (True) or false (False)
(b) Correct the false statement by altering the last word only.
A plant cell placed in hypotonic solution gets Plasmolysed.
The following diagram represents a plant cell after being placed in a strong sugar solution.
Guidelines 1 to 5 indicate the following
(1)Cell wall, (2) Strong sugar solution, (3) Protoplasm (4) Large vacuole, (5) Nucleus
(1)What is the state of the cell shown in the cell shown in the diagram?
(2)Name the structure which acts as a selectively permeable membrane.
(3)If the cell had been placed in distilled water instead of strong sugar solution, which feature would not have been seen?
(4)Name any one feature of this plant cell which is not present in an animal cell.
The diagram given below represents an experimental set-up to demonstrate a certain process. Study the same and answer the questions that follow:
- Name the process.
- Define the above-named process.
- What would you observe in the experimental set-up after an hour or so?
- What control experiment can be set up for comparison?
- Keeping in mind the root hair, cell and its surroundings, name the parts that correspond to
- concentrated sugar solution
- parchment paper
- water in the beaker
- Name any other material that can be used instead of parchment paper in the above experiment.
- Mention two advantages of the process for the plants.
Name the following:
The process by which raisins swell up when placed in a beaker of water.
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:
Comment on the nature (tonicity) of the liquid surrounding the cell.
What is the significance of diffusion?
In an experiment, two sets of apparatus were set up as shown below:
In A there is a concentrated sugar solution inside the thistle funnel and red ink in the water outside the funnel. In B there is a concentrated glucose solution with red ink inside the thistle funnel and water outside the thistle funnel.
In both A and B the level of liquid inside the funnels rises up the tubes. In A the sugar solution turns red and in B, the water turns red.
Study the given observations and answer these questions:
- Name the process by which red ink moves in A and B.
- Which type of pressure forces the water molecules to move towards thistle funnels and cause a rise in the water level?
- Where does this process occur in plants and animals?
- What material could be used as a semi-permeable membrane?
Fill in the Blank
When there is no movement of water in the cell from the outside medium, the medium is considered to be ______ to cell sap.
Explain the term:
Plasmolysis
When a cell in solution shrinks and loses its shape, then the solution is ______.
