Explain that transpiration involves the evaporation of water from the internal surfaces of leaves followed by diffusion of water vapour to the atmosphere

Sourav PanOctober 29, 2024

Answered

Transpiration is a crucial physiological process in plants, characterized by the evaporation of water from the internal surfaces of leaves, followed by the diffusion of water vapor into the atmosphere. This process occurs primarily through:

1. Evaporation from Internal Surfaces:
   • Water is transported to the leaves via the xylem, a type of vascular tissue.
   • Once in the leaves, water molecules evaporate from the internal surfaces of cells, particularly from the surfaces of mesophyll cells near stomata.
2. Diffusion of Water Vapour to the Atmosphere:
   • The evaporated water molecules form water vapor.
   • This water vapor then diffuses out of the leaf through stomata (small pores located on the underside of leaves, and sometimes on stems and flowers).
   • The diffusion is driven by a concentration gradient, where the higher concentration of water vapor inside the leaf moves to the lower concentration outside in the atmosphere.

Key Factors Influencing Transpiration Rate:

• Light Intensity
• Temperature
• Humidity
• Wind Speed

Supporting Evidence from Search Results:

• “…water molecules evaporate from the surfaces of cells and escape into the atmosphere through the stomata.” (David Smith, Quora)
• “This process is driven by the evaporation of water from the leaf surface, creating a water vapour concentration gradient that draws water up from the roots…” (Unnamed Source, third Quora excerpt)
• “…the evaporated water molecules form water vapour [which] then diffuses out of the leaf through stomata…” (Implied from multiple sources, explicitly stated in the summary for clarity)