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The
potometer investigation
Introduction
The
potometer simulation
Suggestions for tasks
How to use the potometer program
Introduction
There
are several aspects to teaching about transpiration. Students should appreciate
that the loss of water from leaves and stems is a natural and essential
process in green plants. They should also study the different environmental
factors that affect the loss of water from a plant. The main objectives
of the simulation are outlined below:
1. All students should
know that plants take up water to replace water lost through transpiration.
2. All students should know one factor that can affect the rate of transpiration.
3. Most students should know that transpiration is important to plants
in maintaining a transpiration stream that draws minerals into plants.
4. Most students should know that the rate of transpiration can be affected
by light intensity, humidity and wind.
5. Most students should know that the rate of transpiration is not the
same as the rate of photosynthesis.
6. Some students should give reasons why a factor such as light intensity
affects the rate of transpiration.
The
potometer simulation
The
potometer investigation generates consistent and realistic results,
showing the uptake of water by a photosynthesising plant, from which the
rate of transpiration is automatically calculated. A feature draws and
print graphs of the data in order to show how transpiration is affected
by various environmental factors.
Suggestions
for tasks
Here are some suggestions
for activities and questions you could try to achieve the objectives listed
above.
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Objective
|
Level
|
Task
|
|
1
|
B,
I
|
Turn on the light,
the fan and the humidifier. Click on the "Next Result" button.
What happens to the bubble in the glass tube? Why does this happen? |
|
2
|
B
|
Turn off the
light, the fan and the humidifier. Click on the "Next Result"
button. Turn one of them back on and take another result. What happens
when one of them is on? |
|
2,
4
|
I,
H
|
Does the fan,
the light or the humidifier affect the movement of the bubble most?
|
|
3
|
I
|
Why does the
bubble move faster when the light is on? What chemical process do
plants carry out in light? |
|
|
H
|
Why doesn't the
bubble move much when it's dark? |
|
5
|
I,
H
|
Does the bubble
stop completely when it's dark? Why not? |
|
6
|
H
|
Why would a plant
need to take in more water when it is light? What difference does
turning the light on make to the mean speed of the bubble? |
How to use the potometer program
The software is easy to use and provides accurate reliable results for
the uptake of water by a plant. There are several buttons, each with a
different function.
1. On the right side of the screen are the control toggle buttons: Light,
Fan, Humidifier. They turn on and off the devices that control
the environmental conditions.
2. On the left side of the screen are the experiment controls:
- Next Result moves the experiment on by one minute and takes
a result.
- Reset resets the whole experiment and clock.
3. As the simulation takes a result, it is automatically plotted on the
graph.
The potometer investigation
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