### Introduction

Aerobic cellular respiration is 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 reaction:

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

All organisms, including plants and animals, oxidize glucose for energy. Often, this energy is used to convert ADP and phosphate into ATP. In this experiment, the rate of cellular respiration will be measured by monitoring the consumption of oxygen gas.

Many environmental variables might affect the rate of aerobic cellular respiration. Temperature changes have profound effects upon living things. Enzyme-catalyzed reactions are especially sensitive to small changes in temperature. Because of this, the metabolism of ectotherms, organisms whose internal body temperature is determined by their surroundings, are often determined by the surrounding temperature. In this experiment, you will determine the effect temperature changes have on the aerobic respiration of yeast.

### Objectives

In this experiment, you will

• Measure changes in dissolved oxygen concentration.
• Study the effect of temperature on cellular respiration.
• Make a plot of the rate of cellular respiration as a function of temperature.