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, supply of carbon dioxide, supply of 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 investigation, you will be using an online simulation to test the effect of light intensity on the
rate of photosynthesis. In the simulation you will prepare an Elodea plant by placing it in different
carbon dioxide solutions. You will then expose it to different light intensities and collect data by
counting the number of bubbles produced by the Elodea plant.
OBJECTIVE/PURPOSE
Determine the effect of light intensity 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. Select 1200 ppm for the CO2 concentration.
4. Select 5000 lux for light intensity.
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 light intensity to 15000 lux and repeat step 5.
7. Change the light intensity to 25000 lux and repeat step 5.
8. 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?
Objective/Purpose
Determine the effect of light intensity on the rate of photosynthesis.
Hypothesis (Write a hypothesis that relates to the purpose of the investigation in an “If…, then…. statement)
Observations
Data Table 1: The effect of light intensity on the rate of photosynthesis.
Light Intensity
5000 lux
15000 lux
25000 lux
Number of
Bubbles
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 light intensity of 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 light?
EXPLAIN.
Critical Thinking (Use the graphs below to answer the following questions)
1. HOW and WHY is the rate of photosynthesis affected by
wavelengths of light? (Hint: What colors are absorbed by plant
pigments?)
2. Predict how the rate of photosynthesis would change if the color
of light used was primarily yellowish-green and explain why.
3. Predict how the rate of photosynthesis would change if the color of light used was red and
explain why.
4. What is the optimum temperature for photosynthesis to occur? Describe how the rate of
photosynthesis is affected by temperature.