Transpiration Flashcards
What is the process to open the stomata for transpiration? 1st part
- ATP-powered proton pump transports hydrogen ions out of guard cell
- Potassium ions diffuse into cell down electrochemical gradient
- Lowers WP inside cell
What is the process of opening the stomata for transpiration? 2nd part
- Water enters cell by osmosis
- Turgid pressure in cell increases
- Thin outer walls bend more easily than thick inner walls
- Cell becomes curved + stomata opens
What are the factors that affect transpiration rate?
Temp, humidity, air movement, light intensity
How does increased temp affect transpiration rate?
Kinetic energy of water molecules increase, so they diffuse faster
How does increased air movement affect transpiration rate?
Removes water molecules as they pass out of leaf, maintaining steep conc gradient for diffusion
How does low humidity affect transpiration rate?
Lowers conc gradient of water outside leaf, steeper conc gradient for diffusion
How does high light intensity affect transpiration rate?
Stomata opens up to allow gas exchange for photosynthesis, water vapour can diffuse out of leaf
What is transpiration?
Movement of water from roots of plant to leaves
What are the properties of water allowing the water to travel up the plant?
Adhesive and cohesive
Water evaporates as it leaves the leaves
