The Bubble Potometer Flashcards
Outline the first 6 steps of the practical
1- The potometer must be immersed in water to remove air bubbles
2- The screw clip opened to fill the tube with water
3- The branch of the plant was cut in the water
4- The end of the branch was inserted under water
5- A beaker of water was placed at the end of the capillary tube
6- Screw clip closed, potometer removed from water
Outline the last 6 steps of the practical
7- Surface of the leaves and stem wiped with tissue paper
8- Vaseline spread around every joint so it’s tight
9- Allow plant to equilibrate for 5 mins before introducing the air bubble
10- Take 3 readings of bubble movement, use reservoir to return bubble to 0
11- Calculate mean and record air temperatures
12- Rate of water uptake per unit area of leaves can be calculated by measurement of leaf area
How would you prepare the rubber tubing?
Should be greased and wired to stop air leaks
How would you use the capillary tube?
Must be horizontal to prevent the air bubble moving due to its density compared with water
What is the reservoir of water for?
May be connected to capillary tubing if tap is opened. It’s used to prevent the air bubble entering the plant and to move the bubble back along the capillary tube.
