Potometer A- Level Bio OCR A
Explain and outline the method of using a potometer - ANS-1. cut a shoot with leaves, and place
into h2o to prevent xylem from absorbing air
2-cut the bottom again underwater(as air bubbles may fill up the xylem) in the lab , keeping the
leaves dry
3-immerse potometer into a sink fill all the tubes and lose any air bubbles
4-place cut stem into a tight bung seal at the end of the potometer
5- with tap closed lift potometer out of sink
6-let the other end form an air bubble, then put free end in h2o to close the bubble
7- let the bubble around the corner, and when beginning experiment note it's position along a
ruler
8-time experiment & measure distance moved
\Explain how accurate Measurements could be taken - ANS-1- regular intervals
2-measure from the same point in bubble as its a circle
3-units of distance=mm/cm
4- construct a table for different time intervals
\Explain how to calculate water uptake/ rate of transpiration - ANS-1- work out VOLUME OF
CYLINDER= V=πr2h
2- RATE= volume/ time
\Explain what needs to be included to ensure the investigation is improved - ANS-1. leafy shoot
needs to be cut underwater
2. leafy cut must represent the entire plant(dont get one that has fruits/sick)
3.keep all factors of transpiration constant EXCEPT the one being measured
4.before recording leafy shoot needs to adjust in potometer
5.keep conditions in lab constant
6. Leaves must be dry otherwise will interfere with transpiration
7. Use leafy shoot with thin waxy cuticle OTHERWISE transpiration is limited
\Explain why anomlies occur? - ANS-1- when measuring bubbles- could be due to a fault in the
apparatus/ misreading scale
2-miscalculation of volume of rates
3- poor control over factors (eg.humidity,temp.,wind,)
\How can the conclusions be made more accurate? - ANS-1-setting up potometer correctly
\how can the conclusions be made more reliable? - ANS-1-repeat experiments experiment
several tmes
2-multiple bubble readings
\how would humidity be controlled - ANS-by wrapping a plastic a plastic bag around the plant to
maintain a humid environment
\How would light intensity be controlled? - ANS-by changing the distance between the lamp and
potometer
\How would wind speed be controlled? - ANS-by putting a fan close to the potometer and
changing it's wind speeds
Explain and outline the method of using a potometer - ANS-1. cut a shoot with leaves, and place
into h2o to prevent xylem from absorbing air
2-cut the bottom again underwater(as air bubbles may fill up the xylem) in the lab , keeping the
leaves dry
3-immerse potometer into a sink fill all the tubes and lose any air bubbles
4-place cut stem into a tight bung seal at the end of the potometer
5- with tap closed lift potometer out of sink
6-let the other end form an air bubble, then put free end in h2o to close the bubble
7- let the bubble around the corner, and when beginning experiment note it's position along a
ruler
8-time experiment & measure distance moved
\Explain how accurate Measurements could be taken - ANS-1- regular intervals
2-measure from the same point in bubble as its a circle
3-units of distance=mm/cm
4- construct a table for different time intervals
\Explain how to calculate water uptake/ rate of transpiration - ANS-1- work out VOLUME OF
CYLINDER= V=πr2h
2- RATE= volume/ time
\Explain what needs to be included to ensure the investigation is improved - ANS-1. leafy shoot
needs to be cut underwater
2. leafy cut must represent the entire plant(dont get one that has fruits/sick)
3.keep all factors of transpiration constant EXCEPT the one being measured
4.before recording leafy shoot needs to adjust in potometer
5.keep conditions in lab constant
6. Leaves must be dry otherwise will interfere with transpiration
7. Use leafy shoot with thin waxy cuticle OTHERWISE transpiration is limited
\Explain why anomlies occur? - ANS-1- when measuring bubbles- could be due to a fault in the
apparatus/ misreading scale
2-miscalculation of volume of rates
3- poor control over factors (eg.humidity,temp.,wind,)
\How can the conclusions be made more accurate? - ANS-1-setting up potometer correctly
\how can the conclusions be made more reliable? - ANS-1-repeat experiments experiment
several tmes
2-multiple bubble readings
\how would humidity be controlled - ANS-by wrapping a plastic a plastic bag around the plant to
maintain a humid environment
\How would light intensity be controlled? - ANS-by changing the distance between the lamp and
potometer
\How would wind speed be controlled? - ANS-by putting a fan close to the potometer and
changing it's wind speeds
