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प्रश्न
Give scientific reasons : Balsam plants wilt during mid-day even if the soil is well watered.
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उत्तर
In case of balsam plants, the rate of transpiration during mid-day exceeds the rate of absorption of water by the roots. The cells therefore lose turgidity. In the evening or during the night, the stomata are constricted and the temperature is not very high; therefore, there is no loss of water through transpiration, and the turgidity of the leaves is re-acquired.
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संबंधित प्रश्न
The diagram given below represents a plant cell after being placed in a strong sugar solution. Study the diagram and answer the questions that follow:

- What is the state of the cell shown in the diagram?
- Name the structure that acts as a selectively permeable membrane.
- Label the parts numbered 1 to 4 in the diagram.
- How can the above cell be brought back to its original condition? Mention the scientific term for the recovery of the cell.
- State any two features of the above plant cell which is not present in animal cells.
A plant cell may burst when :
Mention whether the following statement is true or false Correct the false statement by altering the last word only.
Cells that have lost their water content are said to be deplasmolysed.
Give reason for the following:
It is better to transplant seedlings in a flower-bed in the evening and not in the morning.
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:

- Give the term for the state of the cell it has acquired.
- Name the structure which acts as a selectively permeable membrane.
- Comment on the nature (tonicity) of the liquid surrounding the cell.
- Name any one feature of this plant cell which is not present in an animal cell.
- Redraw in the space provided, the diagram of the cell if it is soon placed in ordinary water for some time.
Give suitable biological reasons for the following statement:
Root hairs become flaccid and droop when excess fertilizers are added to the moist soil around them.
The below diagram represents a plant cell after being placed in a strong sugar solution. Guidelines 1 to 5 indicate the following:
1. Cell wall
2. Plasma membrane.
3. Protoplasm
4. Large vacuole
5. Nucleus
Study the diagram and answer the questions that follow :
(i) What is the state of the cell shown in the diagram?
(ii) Name the structure which acts as a selectively permeable membrane.
(iii) If the cell had been placed in distilled water instead of a strong sugar solution which features: would not have been present?
(iv) If the cell in the diagram possessed chloroplasts where would these be present?
(v) Name any one feature of this plant cell which is not present in animal cells.
Give Technical Term for the following.
A cell in a fully extended condition.
Give Technical Term for the following.
The pressure exerted by cell contents on a plant cell wall.
Name the following:
The process by which wilting or drooping of leaves occurs.
