Vernier Software and Technology
Vernier Software & Technology


Figure from experiment 7 from Biology with Vernier


The process of photosynthesis involves the use of light energy to convert carbon dioxide and water into sugar, oxygen, and other organic compounds. This process is often summarized by the following reaction:

{\text{6 }}{{\text{H}}_{\text{2}}}{\text{O + 6 C}}{{\text{O}}_{\text{2}}}{\text{ + light energy }} \to {\text{ }}{{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}{\text{ + 6 }}{{\text{O}}_{\text{2}}}

This process is an extremely complex one, occurring in two stages. The first stage, called the light reactions of photosynthesis, requires light energy. The products of the light reactions are then used to produce glucose from carbon dioxide and water. Because the reactions in the second stage do not require the direct use of light energy, they are called the dark reactions of photosynthesis.

In the light reactions, electrons derived from water are “excited” (raised to higher energy levels) in several steps, called photosystems I and II. In both steps, chlorophyll absorbs light energy that is used to excite the electrons. Normally, these electrons are passed to a cytochrome-containing electron transport chain. In the first photosystem, these electrons are used to generate ATP. In the second photosystem, excited electrons are used to produce the reduced coenzyme nicotinamide adenine dinucleotide phosphate (NADPH). Both ATP and NADPH are then used in the dark reactions to produce glucose.

In this experiment, a blue dye (2,6-dichlorophenol-indophenol, or DPIP) will be used to replace NADPH in the light reactions. When the dye is oxidized, it is blue. When reduced, however, it turns colorless. Since DPIP replaces NADPH in the light reactions, it will turn from blue to colorless when reduced during photosynthesis.


In this experiment, you will

  • Use a Spectrometer or Colorimeter to measure color changes due to photosynthesis.
  • Study the effect of light on photosynthesis.
  • Study the effect that the boiling of plant cells has on photosynthesis.
  • Compare the rates of photosynthesis for plants in different light conditions.

Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

Option 1

Option 2

Option 3

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Standards Correlations

See all standards correlations for Biology with Vernier »

Biology with Vernier

See other experiments from the lab book.

1Energy in Food
2Limitations on Cell Size: Surface Area to Volume
3Acids and Bases
4Diffusion through Membranes
5Conducting Solutions
6AEnzyme Action: Testing Catalase Activity
6BEnzyme Action: Testing Catalase Activity
8The Effect of Alcohol on Biological Membranes
9Biological Membranes
11ACell Respiration (O2)
11BCell Respiration (CO2)
11CCell Respiration (Pressure)
11DCell Respiration (CO2 and O2)
12ARespiration of Sugars by Yeast
12BSugar Fermentation
13Population Dynamics
14Interdependence of Plants and Animals
15Biodiversity and Ecosystems
16AEffect of Temperature on Respiration
16BEffect of Temperature on Fermentation
17Aerobic Respiration
18Acid Rain
19Dissolved Oxygen in Water
20Watershed Testing
21Physical Profile of a Lake
23AEffect of Temperature on Cold-Blooded Organisms
23BEffect of Temperature on Cold-Blooded Organisms
24ALactase Action
24BLactase Action
25Primary Productivity
26Control of Human Respiration
27Heart Rate and Physical Fitness
28Monitoring EKG
29Ventilation and Heart Rate
30Oxygen Gas and Human Respiration
31APhotosynthesis and Respiration (O2)
31BPhotosynthesis and Respiration (CO2)
31CPhotosynthesis and Respiration (CO2 and O2)

Experiment 7 from Biology with Vernier Lab Book

<em>Biology with Vernier</em> book cover

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