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Question
Give scientific reasons : Balsam plants wilt during mid-day even if the soil is well watered.
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Solution
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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RELATED QUESTIONS
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 :
Explain Turgor pressure
Give the equivalent term for the following:
Loss of water through a cut stem.
Differentiate between the following:
Turgidity and Flaccidity
Give reason for the following:
A plant cell, when kept in a hypertonic salt solution for about 30 minutes, turns flaccid.
Name the following:
The process by which wilting or drooping of leaves occurs.
Multiple Choice Question:
When cell is fully turgid, which of the following will be zero?
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
