Rate of Photosynthesis Lab
Research Question: What factors affect the rate of photosynthesis in plants?
Light intensity is one of the factors affecting the rate of photosynthesis. Other factors are
concentration of carbon dioxide, temperature and to a lesser degree, water. Light intensity directly
affects the light-dependent reaction in photosynthesis and indirectly affects the light-independent
reaction. Light is a limiting factor when the light intensity is too low to allow the light-dependent
reaction to proceed at its maximum rate. Light is not normally a limiting factor except for plants in
forest understory of other shaded plants. Very high light intensities may slow the rate of
photosynthesis due to bleaching of chlorophyll. However, plants exposed to such conditions usually
have protective features to include thick, waxy cuticles and hairy leaves. Other factors that can limit
the rate of photosynthesis include carbon dioxide concentration, temperature, and color of light.
Bubbles are given off by the plant through Photosynthesis. By measuring the rate at which the
bubbles are produced it is possible to tell how fast the plant is photosynthesizing.
Procedure:
1) Go to the website: https://amrita.olabs.edu.in/?sub=79&brch=16&sim=126&cnt=4 to find the
Importance of Light in Photosynthesis Simulator
2) The default settings are set to 40W for power, 50cm for distance, and Clear for color source.
Press “Start” to begin each trial. Record how many bubbles are released from the plant in
about 1 min (the clock is sped up in the simulator). Record your results below.
3) When you are satisfied you have a reliable result, click the back button to move the light to a
different position, reset the clock, and take another reading.
4) Continue this process by changing the light power, distance, and color. Record all results
below.
Data Table (6 points)
Light Power (W)
Distance (cm)
Color
40W
50cm
Clear
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Copying or distributing without K12’s written consent is prohibited.
Minutes
Seconds
Number of
Bubbles
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Conclusion Questions: (4pts)
1) Based on the result in your data table, how does light intensity and color affect the rate of photosynthesis?
2) Watch the following video to help answer the question: https://youtu.be/1curtzL8rUM
© 2008 K12 Inc. All rights reserved.
Copying or distributing without K12’s written consent is prohibited.
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