Potometer Flashcards
What is a potometer?
A piece of equipment used to investigate the rate of transpiration of a plant
Does the potometer actually measure rate of transpiration?
No, measures water uptake
However these values are very similar: as a very small amount of water from water uptake by plant is taken into cells, as the rest is evaporated in transpiration
Why do we cut the stem of the plant we are measuring the rate of transpiration of?
To prevent air from entering xylem and at a slant (to increase the surface area)
Potometer apparatus
Capillary tube with scale
Into a beaker of water
Attached to a reservoir of water with a tap
Attached to place with stem
Why do we assemble the potometer apparatus underwater?
To ensure no air bubbles enter
What does the reservoir and tap do?
Supplies more water to restart the measurement: pushes air bubble back
What is important to let plant do?
Equilibrate to these new conditions to measure true rate of transpiration under the new manipulated conditions by drying leaves
How do we use the potometer to measure rate of transpiration?
Introduce an air bubble into the tube by lifting capillary tube from water beaker
Recording the distance it travelled/ area of tube it travelled within the tub per given time
How to find volume of water air bubbled?
By calculating the area of the capillary tube it travelled as if it were a cylinder
