Which of the following physical forces are supposed to be responsible ...
Transpirational pull creates upward pressure while cohesion attached water molecule with each other
Which of the following physical forces are supposed to be responsible ...
Understanding the Ascent of Sap
The ascent of sap in plants is a complex process primarily driven by physical forces, among which transpiration pull and cohesion play a critical role.
Key Forces Involved in Ascent of Sap:
- Transpiration Pull:
- Transpiration is the process of water vapor loss from plant leaves.
- As water evaporates from the surface of leaves, it creates a negative pressure within the leaf's air spaces.
- This negative pressure pulls more water upward from the roots through the xylem vessels.
- Cohesion:
- Water molecules exhibit strong cohesive forces due to hydrogen bonding.
- This cohesion allows water molecules to stick together, forming a continuous column of water in the xylem.
- The cohesive strength helps resist the gravitational pull, allowing the sap to ascend efficiently.
Other Forces Mentioned:
- Imbibition:
- Imbibition refers to the absorption of water by solids, such as seeds or plant fibers.
- While important for seed germination, it does not directly contribute to sap ascent.
- Capillary Force:
- Capillary action involves the movement of water within the tiny xylem vessels.
- Although it assists in the movement of water, it is not the primary force driving the ascent of sap.
- Root Pressure:
- Root pressure is generated when minerals and nutrients are actively transported into the roots, causing water to enter the root through osmosis.
- While it can help in pushing sap upward, it is not as significant as transpiration pull.
Conclusion:
The combination of transpiration pull and cohesion is essential for the efficient ascent of sap, making option 'C' the correct answer.
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