Transpiration and Stomata Flashcards
Organisation (12 cards)
What are the four main factors that affect transpiration rate?
- Light Intensity
- Temperature
- Air Flow
- Humidity
Each factor influences how much water vapor is lost from the leaves.
How does light intensity affect transpiration rate?
The brighter the light, the greater the transpiration rate. Stomata close in darkness, reducing water escape.
Photosynthesis requires open stomata to take in CO₂, which is not needed in the dark.
What is the relationship between temperature and transpiration rate?
The warmer it is, the faster transpiration happens, as warmer water particles have more energy to evaporate.
Increased temperature enhances the movement of water particles out of the stomata.
How does air flow influence transpiration?
Better air flow around a leaf increases transpiration rate. Poor air flow leads to high concentration of water vapor around the leaf, slowing diffusion.
Strong wind helps remove water vapor from around the leaf.
What effect does humidity have on transpiration?
The drier the air around a leaf, the faster transpiration happens. High humidity reduces the concentration difference needed for diffusion.
Diffusion is most efficient when there is a significant difference in water vapor concentration.
How can you estimate the rate of transpiration in a plant?
By measuring the uptake of water by a plant, which is directly related to water loss by the leaves.
This can be done using a potometer to measure the movement of an air bubble.
What is a potometer used for?
A potometer is used to measure the rate of water uptake by a plant, which indicates transpiration rate.
Setting it up requires careful attention to ensure consistent conditions.
Describe the structure and function of guard cells.
Guard cells have a kidney shape that opens and closes stomata, controlling gas exchange and water loss.
They become turgid with water to open stomata and flaccid to close them.
What happens to guard cells when the plant has lots of water?
Guard cells fill with water and become turgid, causing the stomata to open for gas exchange.
This facilitates photosynthesis by allowing CO₂ in.
What occurs to guard cells when the plant is short of water?
Guard cells lose water and become flaccid, which closes the stomata to prevent excessive water loss.
This adaptation helps the plant conserve water during drought conditions.
How are guard cells adapted for their function?
They have thin outer walls and thickened inner walls, which aid in opening and closing stomata.
Their sensitivity to light also helps regulate water loss at night.
Where are stomata usually found on a leaf?
More stomata are typically found on the undersides of leaves than on the top.
The lower surface is shaded and cooler, which reduces water loss.
