Vernier Software & Technology

Photosynthesis

Introduction

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.

Objectives

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 3

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

Biology with Vernier

See other experiments from the lab book.

 1 Energy in Food 2 Limitations on Cell Size: Surface Area to Volume 3 Acids and Bases 4 Diffusion through Membranes 5 Conducting Solutions 6A Enzyme Action: Testing Catalase Activity 6B Enzyme Action: Testing Catalase Activity 7 Photosynthesis 8 The Effect of Alcohol on Biological Membranes 9 Biological Membranes 10 Transpiration 11A Cell Respiration (O2) 11B Cell Respiration (CO2) 11C Cell Respiration (Pressure) 11D Cell Respiration (CO2 and O2) 12A Respiration of Sugars by Yeast 12B Sugar Fermentation 13 Population Dynamics 14 Interdependence of Plants and Animals 15 Biodiversity and Ecosystems 16A Effect of Temperature on Respiration 16B Effect of Temperature on Fermentation 17 Aerobic Respiration 18 Acid Rain 19 Dissolved Oxygen in Water 20 Watershed Testing 21 Physical Profile of a Lake 22 Osmosis 23A Effect of Temperature on Cold-Blooded Organisms 23B Effect of Temperature on Cold-Blooded Organisms 24A Lactase Action 24B Lactase Action 25 Primary Productivity 26 Control of Human Respiration 27 Heart Rate and Physical Fitness 28 Monitoring EKG 29 Ventilation and Heart Rate 30 Oxygen Gas and Human Respiration 31A Photosynthesis and Respiration (O2) 31B Photosynthesis and Respiration (CO2) 31C Photosynthesis and Respiration (CO2 and O2)

Experiment 7 from Biology with Vernier Lab Book

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.