Exercise 11: Water Dynamics In Plants

• Transpiration - exit of water in the form of vapor, and may occur as stomatal, cuticular, or lenticular and helps facilitate the upward transport of important minerals in the plant
• What are some factors that affect transpiration rate?

  Temperature, humidity, wind speed, light intensity
• Stomata - primary sites of transpiration and gas exchange in leaves.
• Changes in the turgor pressure of guard cells and light intensity play major roles in the regulation of the stomatal pore.
• Changes in the turgor pressure within structures called pulvinus help facilitate rapid movements of the leaf closing.
• Potometer - enclosed water system, between a burette or pipette and a plant and is used to measure transpiration rate.
• In the regulation of transpiration, water leaves in the form of vapor primarily through the stomates
• Transpiration rate - change in water level of time
• In the regulation of stomatal pores, when the guard cells are turgid, the stoma is open
• Movement of water between guard cells and the accessory cells determines the opening or closing of the stoma
• In the experiment, what was applied on the surface of the leaves so that the stomates would be plugged?

  petroleum jelly
• In the potometer setup, by principle, the water level should decrease within the burette as water moves towards the shoot due to the existing potential gradient between the plant and the air space.
• Guttation - Release of liquid water from a plant leaf due to temporal changes in water potential.
• Hydathodes - leaf organ that is responsible for guttation in plants
• What is the relationship of the number of stoma, light intensity, humidity, and wind speed with the transpiration rate respectively?

  Stomata: Direct Light intensity: Direct Humidity: Inverse Wind speed: Direct
• What do the subsidiary cells in the stomatal complex contain that regulate the movement of the guard cells?

  Potassium ions