Cell Respiration (Pressure)

Recommended for grades 6–12.

Figure from experiment 11C from Biology with Vernier

Introduction

Cell respiration refers to the process of converting the chemical energy of organic molecules into a form immediately usable by organisms. Glucose may be oxidized completely if sufficient oxygen is available, by the following equation:

${{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}} + {\text{ 6 }}{{\text{O}}_{\text{2}}}\left( {\text{g}} \right) \to {\text{6 }}{{\text{H}}_{\text{2}}}{\text{O }} + {\text{ 6 C}}{{\text{O}}_{\text{2}}}\left( {\text{g}} \right) + {\text{ energy}}$

All organisms, including plants and animals, oxidize glucose for energy. Often, this energy is used to convert ADP and phosphate into ATP.

To measure the rate of cell respiration, the pressure change due to the consumption of oxygen by peas will be measured. It is not possible to directly measure pressure changes due to oxygen, since the pressure sensor measures the total pressure change. Carbon dioxide is produced as oxygen is consumed. The pressure due to CO₂ might cancel out any change due to the consumption of oxygen. To eliminate this problem, a chemical will be added that will selectively remove CO₂. Potassium hydroxide, KOH, will chemically react with CO₂ by the following equation:

${\text{2 KOH }} + {\text{ C}}{{\text{O}}_{\text{2}}} \to {{\text{K}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}} + {{\text{H}}_{\text{2}}}{\text{O}}$

This will allow you to monitor pressure changes exclusively due to the consumption of oxygen.

Objectives

In this experiment, you will

Measure gas production.
Study the effect of temperature on cell respiration.
Determine whether germinating peas and non-germinating peas respire.
Compare the rates of cell respiration in germinating and non-germinating peas.

Sensors and Equipment

This experiment requires each of the following Vernier sensors and equipment (unless otherwise noted):

Gas Pressure Sensor (2)

Additional Requirements

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

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Step-by-step instructions for computer-based data collection
List of materials and equipment

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Standards Correlations

No standards correlations for this experiment.