Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Transpiration is the loss of water in the form of water vapor () from the aerial parts (leaves and stems) of a plant.
The Mechanism of Stomatal Transpiration involves the turgidity of guard cells. When guard cells absorb water and become turgid, the stomatal pore opens. This is often regulated by the active transport of Potassium ions () into the guard cells.
Types of Transpiration: 1. Stomatal (approx. ), 2. Cuticular (loss through the waxy ), and 3. Lenticular (loss through small openings in woody stems called ).
Factors affecting the rate include Light (increases rate), Temperature (increases rate), Humidity (decreases rate as the concentration gradient of molecules decreases), and Wind Velocity.
The Transpiration Pull is a suction force created by the evaporation of water from leaf cells, which facilitates the upward movement of water and minerals (Ascent of Sap) from the roots.
Adaptations to reduce transpiration include sunken stomata, thick cuticles, and leaves modified into spines (as seen in or ).
📐Formulae
💡Examples
Problem 1:
In a Ganong's Potometer experiment, the air bubble moves a distance of in . Calculate the rate of transpiration in .
Solution:
Explanation:
The rate of transpiration is measured by the speed of the air bubble, which indicates the volume of absorbed by the plant to replace the water lost through transpiration.
Problem 2:
Why does a piece of dry Cobalt Chloride paper change color from Blue to Pink when placed on the underside of a leaf?
Solution:
Explanation:
Anhydrous Cobalt Chloride is blue. When it comes into contact with vapor transpired through the stomata, it becomes hydrated (), turning pink. This confirms that water vapor is being released from the leaf surface.