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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 below represents a process in plants. The setup was placed in bright sunlight. Answer the following questions:
a) Name the physiological process depicted in the diagram.
Why was oil added to the water?
b) When placed in bright sunlight for four hours, what do you observe with regard to the initial and final weight of the plant? Give a suitable reason for your answer
c) What happens to the level of water when this setup is placed in:
- Humid conditions?
- Windy conditions?
d) Mention any three adaptations found in plants to overcome the process mentioned in (i).
e) Explain the term ‘Guttation’.
The state of a cell in which the cell wall is rigid and stretched by the increase in volume due to the absorption of water is called.
Give the equivalent term for the following:
The condition in which the cell contents are shrunken.
Differentiate between the following:
Turgidity and Flaccidity
What is the difference between ‘flaccid’ and ‘turgid’? Give one example of flaccid condition in plants.
Give reason for the following:
It is better to transplant seedlings in a flower-bed in the evening and not in the morning.
Name the following:
The process by which wilting or drooping of leaves occurs.
Fill in the Blank
Wilting and drooping of leaves is due to loss of ________.
Excessive use of fertilisers in agricultural fields reduces the yield of crops. Justify the statement.
The figure given below is a diagrammatic representation of a part of the cross-section of the root in the root hair zone. Study the same and then answer the questions that follow:
- The parts labelled as 1, 2, 3 and 4 are:
- Root hair, Xylem vessel, Soil particles, Cortex respectively.
- Xylem vessel, Soil particles, Root hair, Cortex respectively.
- Root hair, Xylem vessel, Cortex, Soil particles respectively.
- Cortex, Soil particles, Xylem vessel, Root hair respectively.
- The process that enables the passage of water from soil into the root hair is:
- Diffusion
- Active transport
- Osmosis
- Passive absorption
- The kind of force which exists between a liquid and any surface is called as:
- Cohesive force
- Adhesive force
- Capillarity
- Suction force
- The kind of force between the same kind of liquid molecules is:
- Capillary force
- Transpirational pull
- Adhesive force
- Cohesive force
- Sometimes exudation of water occurs from the margin of the leaves in the early morning or night. It is termed as:
- Transpiration
- Guttation
- Bleeding
- Osmosis
