Use Of A Potometer Flashcards
1
Q
What is transpiration?
A
Loss of water vapour from the stomata by evaporation
2
Q
What is the rate of transpiration affected by?
A
- temperature
- humidity
- air movement
- light intensity
3
Q
What is a potometer?
A
A device that measures the uptake of water from a plant and can be used to measure the effect of a named environmental variable on the rate of transpiration
4
Q
How do you use the potometer?
A
- a sample of the plant is cut underwater to prevent air entering the xylem
- the potometer is filled with water and all bubbles are removed
- the sample is attached to the potometer using rubbers seals and petroleum jelly to make it airtight
- one air bubble is introduced into the equipment and the distance this air bubble has moved towards the plant in a certain time is recorded
5
Q
How do you calculate the rate of transpiration from the results?
A
Volume / time taken = rate
6
Q
Why are rubber seals and petroleum jelly used?
A
To keep the potometer airtight so no unwanted bubbles appear
7
Q
What is the independent variable in the potometer?
A
The time
8
Q
What is the dependent variable?
A
The distance moved by the bubble along the capillary tube
9
Q
What are the control variables?
A
Temperature, air flow, adequate supply of water
