3.1.3 Plant Transport – Transpiration Flashcards
(14 cards)
What is transpiration?
The loss of water vapour through evaporation from the stomata of leaf.
What is the transpiration stream?
The continuous movement of water from the soil to air through a plant, brought about by the loss of water vapour from the leaves.
Why is transpiration a consequence of photosynthesis?
- The stomata must be open for carbon dioxide to diffuse in for photosynthesis to occur.
- The open stomata mean that water vapour can evaporate and diffuse out of the plant.
Which 4 factors increase transpiration?
- Low humidity
- High temperatures
- High light intensity
- Wind
Which 4 factors decrease transpiration?
- High humidity
- Low temperatures
- Low light intensity (stomata close as no photosynthesis is occurring)
- Lack of wind
Explain why a high temperature increases transpiration rate.
- A high temperature gives the water molecules more kinetic energy.
- Therefore water is able to evaporate faster.
What does a potometer measure?
The volume of water taken up by a plant.
Why should the shoot be cut under water before being used in a potometer?
It prevents air entering the plant and ensures the water travels in a continuous column.
What is the function of petroleum jelly when setting up a potometer?
It ensures the potometer is air tight.
What is the function of the reservoir in the potometer?
It allows the potometer to be refilled with water, so that the air bubble can be moved to the start.
Once the potometer has been set up, what must you allow to happen before taking any measurements?
It must acclimatise to the environment.
What measurements do you take from a potometer in order to calculate the rate of transpiration?
The distance an air bubble has moved in a given time.
What calculation would allow you to find convert the distance the air bubble has moved into a volume of water taken up by the plant?
=π r2l
r = radius of capillary tube
l = length of capillary tube (the distance the air bubble has moved)
Why would you repeat the experiment to get multiple results?
To increase the reliability of the results.
To identify anomalous results.
To calculate the mean.
