Photosynthesis Online Investigation
-- CLASS COPY -BACKGROUND
Photosynthesis is the process in which plants use sunlight to convert carbon dioxide
and water into the simple sugar glucose and oxygen gas. The rate at which
photosynthesis occurs is not always the same. The intensity of light, amount of carbon
dioxide and water, and the availability of minerals are important factors that affect the
rate of photosynthesis in plants. The rate also varies by species and a plant’s health and
maturity.
In this online investigation, an Elodea plant will be used to simulate the effect of light
intensity and carbon dioxide concentration on the rate of photosynthesis.
Photosynthesis rate will be measured by counting the number of bubbles produced at a
particular light intensity and different carbon dioxide levels.
Objective/Purpose:
Determine the effect of light intensity and carbon dioxide concentration on the rate of
photosynthesis.
Procedure:
1. Go to the following website:
www.newpathlearning.com/MML/PHOTOSYNTHESIS/files/BubbleLab.swf
2. Click on the prepare plant button.
3. Using your knowledge of light intensity and photosynthesis, determine the light
intensity that would produce the most bubbles in the simulation. Use this light
intensity to run the rest of the simulations.
4. Select 0 ppm for the CO2 concentration.
5. Click on the start button and count the number of bubbles produced in 5 minutes.
(IMPORTANT: Note that the speed of the timer is stimulated). Record the number of
bubbles in a data table.
6. Change the CO2 concentration to 300 ppm and repeat step 5.
7. Change the CO2 concentration to 600 ppm and repeat step 5.
8. Change the CO2 concentration to 1200 ppm and repeat step 5.
9. Share your group data with the class.
NAME: _______________________________________
PERIOD: ______
DATE: _______________
Photosynthesis Online Investigation
Pre-Lab Questions (Answer questions in complete sentences)
1. What does a plant need for photosynthesis to occur?
2. What factors can affect the rate of photosynthesis?
3. Why can the number of bubbles produced indicate the rate of photosynthesis?
Hypothesis: (Hypothesis should relate to the purpose of the investigation in an “If…, then…. because statement)
Observations:
Light intensity that would produce the most bubbles in the simulation:
Data Table 1: The effect of carbon dioxide levels on the rate of photosynthesis.
Carbon Dioxide
0 ppm
300 ppm
600 ppm
Concentration
Number of Bubbles
1200 ppm
Qualitative Data:
Collect data from all of the groups in your class and organize it in a data table below.
Data Table 2:
Graph
On a separate sheet of paper, create a LINE graph that represents the effect of carbon dioxide
concentration on the rate of photosynthesis. STAPLE the graph paper to this lab before turning it in.
Analysis
1. What conclusion can you draw about the rate of photosynthesis and its relationship to carbon
dioxide concentration? EXPLAIN.
Conclusion
Does the data support
your hypothesis? (Restate
hypothesis in the answer)
List data from simulation
to support the above
claim.
Use what you have
learned in class to
explain WHY you got
these results.
What is the relevance of
the findings from this
experiment? (Why would
this be useful to know?)
What are some possible
sources of error
(mistakes that were
made) that could have
affected the outcome of
the experiment?
What are some other
questions or factors about
the rate of photosynthesis
that you could test?