ZURICH INTERNATIONAL SCHOOL
Coordinated Science I
Name_________________________________
Date____________
Online Exploration: Photosynthesis Lab
Using Internet Explorer, visit http://www.explorelearning.com/ and search: "Photosynthesis". Launch the Gizmo
"Photosynthesis Lab." Enter the enrolment code 7TP6VVHCGQ and quickly register yourself (you DO NOT need to
provide your email address to them).
A. Reaction Warm-Up
During photosynthesis plants use the energy of ____________ to produce
________________ from _________________ and _____________ .
 Glucose is a simple sugar that plants use for energy and as a building block for
larger molecules.
 A by-product of photosynthesis is _________________. Plants use some of the
oxygen they produce, but most of it is released.
o In the Photosynthesis Lab Gizmo™, you can monitor the rate of
photosynthesis by measuring oxygen production.
B. Gizmo Warm-Up


By moving the sliders on the carbon dioxide, light intensity, and temperature you can adjust the conditions for
the plant.
Explore the tabs on the top right to see what the Gizmo is capable of doing.
C. Activity #1: What is the effect of limiting factors on photosynthesis?
Get the Gizmo ready:
 Select the WHITE tab and the BAR CHART tab.
 Turn on "Show numerical values".
Introduction: Photosynthesis requires light, water, and CO2 to work. When one of these factors is in short supply, it is
called a limiting factor. Temperature can also be a limiting factor when it is too hot or too cold for photosynthesis to
work well.
1. Select one limiting factor that you would like to investigate: ___________________________
2. Write a hypothesis on how that variable affects the rate of photosynthesis. Use "If...then…because…"
3. Design an experiment to test this hypothesis.
a) Determine the treatment values (the experimental range) for your independent variable and fill them into
Table 1 (top of the next page).
b) Set the values for the other variables (control variables) that you must keep constant. Record:
Control Variable 1: ___________________________
Value: _____________________
Control Variable 2: ___________________________
Value: _____________________
Table 1. Raw data collected (don't forget to fill in the IV and DV you are working with in the heading of the graph,
including units)
Independent Variable:
Dependent Variable:
*Please note that because this simulation gives you
the same results every time, you do not need to have
multiple trials for each value.
4. Gather Data: Using your independent variable and the
selected control variables, gather data using the simulation
and record it in your table.
5. Create a line graph of your data on the axis provided:
6. Conclusion: Was your hypothesis supported or refuted? How do you know (refer to data points)?
7. Challenge: Use the Gizmo to create each of the following scenarios. For each one, determine which of the factors is
the limiting factor.
Scenario
Temperature (°C)
Light intensity (%)
CO2 level (ppm)
A
25
60
700
B
15
20
200
C
30
50
400
Limiting factor
8. Think and discuss: Suppose you were a farmer trying to grow plants in a greenhouse. Why would it be important to
know what the limiting factor of the greenhouse is?
D. Activity #2: What are the ideal conditions for photosynthesis?
Get the Gizmo ready:
 Be sure that the BAR CHART tab is selected.
 Turn on "Show numerical values".
Recap: During photosynthesis, light energy is used to synthesize carbon dioxide (CO2) and water (H2O) into glucose
(C6H12O6) and oxygen (O2). The complex series of chemical reactions is summarized by the chemical equation below. Fill
in the blanks to balance it.
_____ CO2 + _____ H2O + light energy _____ C6H12O6 + _____ O2
1. Experiment: Use the Gizmo to find the ideal conditions for photosynthesis. Use any method you like. When you think
you have the answer, list the conditions below.
Temperature (°C)
Light intensity (%)
CO2 level (ppm)
O2 production (mL/h)
2. Comparison: Compare your results to a friend. How did they determine their optimal levels? Did you use different
methods? Who is right?

If necessary, explore some more and revise your numbers in the table above.
3. Think and discuss: Think about the process of finding the ideal conditions.
a. Why would it be hard to find the ideal light intensity if the temperature were very hot or cold?
b. Why would it be hard to find the ideal CO2 level if the light intensity were very low?
E. Activity #3: What color of light is the best for photosynthesis?
Get the Gizmo ready:
 Select the COLOR tab and the BAR CHART tab.
 Set the Temperature to 24°C, the Light intensity to 90%, and the CO2 level to 1,000 ppm.
 Turn on "Show numerical values".
Introduction: Plants use a green pigment called chlorophyll to absorb light and convert its energy into a form that the
plant can use. Chlorophyll gives plants their green color.
1. Initial thought: Which color of light do you think will maximize the rate of photosynthesis?
_________________________________________________________________________
2. Gather data: Set the Light wavelength to 400 nm. (nm stands for
nanometers. A nanometer is a billionth of a meter.) Visible light
ranges from 400 to 700 nm.
On the TABLE tab, click Record data. Then set the Light wavelength
to 420 nm, and repeat. Continue recording data in the Gizmo every
20 nm until the wavelength is 700 nm.
3. Make a graph: Select the GRAPH tab and select Wavelength.
Sketch the graph in the space at right.
4. Analysis:
a. Which colors were absorbed best by the plant?
_________________________
b. Which colors were absorbed worst?
_________________________
c. Revisit your "Initial thought" above. Were you right?
5. Think and discuss: When we look at a leaf, we see the colors of light
that are reflected off its surface. How does this explain the relatively
low rate of photosynthesis in green light?