Potometer

Question 1

How does photometer work

Answer 1

Assemble potometer with capillary tube end submerged in a beaker of water
- Insert shoot underwater
- Ensure apparatus is watertight and airtight
- Dry leaves and allow time for the shoot to acclimatise
- Shut off tap to reservoir
- Remove the end of the capillary tube from the water beaker until one hair bubble has
formed, then put the tube back into the water
- Record the position of the air bubble
- Use a stopwatch to record time e.g. one minute
- Record distance moved per unit time
- Rate of air movement = estimate of transpiration rate
- Change one variable at a time and keep all other variables constant (wind, humidity, light
and temperature)

Question 2

Two equation needed in potometer

Answer 2

Rate=distance moved/time

Volume of water = distance moved x area of circle

Question 3

What reservoir allow

Answer 3

Bubbles to be returned to start

Question 4

What does using healthy root ensure

Answer 4

Stomata are open

Transpiration can happen

Question 5

Why should leaves be dried

Answer 5

Moist leaves would affect water potential gradient from stomata