- Why is it important to cut the stem at an angle under the water?
- Which part of the stem does the straw represent?
- Which three factors are you investigating?
- Under which condition is the highest rate of transpiration?
- Name one possible error that could have occurred in your investigation.
- What are the potential limitations of this investigation?
Investigation: Determining the effect of light intensity on transpiration
Aim:
To determine the effect of light intensity on transpiration
Apparatus:
- plants
- plastic bag
- piece of string
- graduated measuring cylinder
Method:
- Use at least three plants of the same species and as close to the same size as possible
(think of why this might be important). - Ensure that all three plants are exposed to the same amount of light.
- Use clear plastic bags to completely cover all the leaves of each plant.
- Tie the bottom of the plastic around the main stem of the plant, allowing the water lost
from the plant to collect inside the bag. Try not to crush the leaves of the plant with
the bag. - Place the bags on the plants early in the morning. Leave the bags on all day and check
for signs of water drops inside. If there are water drops, shake the bag so that the water
drops to the bottom of the bag. - At the end of the experiment (the following morning), carefully remove the bags to
ensure that you do not lose any water. Collect the water inside a measuring cylinder
and measure how much water the plant has lost. Collect the amount of water lost
every four hours over 12 hours before leaving the plant overnight.
Results:
Record the amount of water lost at each time point.
Plot a bar graph with time of the day on the horizontal axis and the amount of water collected
on the vertical axis.
Plot another graph with the average water loss in millilitres on the y-axis and the time on the
x-axis.
Chapter 6. Support and transport systems in plants 175