Question

Explain transpiration in plants.

Answer 1

Transpiration in plants:

1. Plants, like all living things, require an excretory system to remove excess water from their bodies.
2. Transpiration is the process of eliminating surplus water from the plant body.
3. The evaporation of water from the surface of the leaves is the most common cause.
4. Water molecules in the plant tissues are removed from the aerial regions of the plants during transpiration.
5. Plants only use a small portion of the water they absorb for growth and development.
6. The remainder is expelled through transpiration.
7. Water has strong tensile strength, or the ability to withstand a pulling force, and high capillarity, or the ability to rise in thin tubes, because of these qualities. The tiny diameter of the tracheary elements – the tracheids and vessel elements – aids capillarity in plants.
8. Photosynthesis necessitates the presence of water.
9. Water can be supplied by the xylem vessel system, which runs from the root to the leaf vein.
10. Because the thin coating of water on the cells is continuous as water evaporates through the stomata, water is drawn into the leaf from the xylem molecule by molecule.
11. Water diffuses into the surrounding air due to the decreased concentration of water vapor in the atmosphere compared to the substomatal cavity and intercellular gaps. This provides a 'pull' effect.

Stomata:

1. It occurs mainly through stomata.
2. Stomata are made up of two guard cells connected by an opening. It is open during the day and shuts down at night. The turgidity of guard cells is the explanation for this structure's opening and shutting.
3. The dense and flexible inside wall of the guard cells faces the aperture. When the guard cells become more turgid, the stomata open. The inside walls form a crescent shape, while the external walls flare out.
4. The direction of the microfibrils in the guard cells is also necessary for the stomata to open. The microfibrils' radial orientation makes it easier for the stomata to open.
5. When the turgidity of the guard cells reduces owing to water loss, the stomata close, and the interior walls revert to their previous shape.

Factors affecting transpiration:

1. Temperature, light, humidity, and wind speed are all elements that influence transpiration.
2. Number and distribution of stomata, percent of open stomata, water status of the plant, canopy structure, and other plant variables all influence transpiration.

Ascent of xylem sap:

The ascent of xylem sap caused by transpiration is primarily determined by the physical characteristics of water:

1. Cohesion - the attraction of water molecules to one another.
2. Adhesion - the attraction of water molecules to polar surfaces (such as tracheary elements' surfaces).
3. Surface Tension - In the liquid phase, water molecules are more attracted to each other than in the gas phase.

The importance of transpiration:
The importance of transpiration is explained in the following paragraphs:

1. Transpiration aids in the transportation of water and minerals throughout the plant.
2. Water balance is maintained inside the plant due to the constant removal of water from the plant body.
3. It keeps the cells stiff and maintains osmosis.
4. Transpiration creates a suction force that aids in the upward transport of water in plants.
5. The accumulation of certain hydrophilic salts on the surface of the leaves keeps the leaves moist.
6. It keeps the cells turgid and aids cell division.