Aerobic and anaerobic respiration

AQA·Biology (Combined Science)·4.4.2.1·Trilogy — Foundation

Aerobic respiration

Cells release energy from nutrient molecules through a series of chemical reactions called aerobic respiration. These reactions use oxygen to break down the nutrient molecules.

When the nutrient is glucose, the overall reactants and products are shown by this word equation:

glucose+oxygen→carbon dioxide+water\text{glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water}

Glucose and oxygen are the reactants: they are used in the reactions. Carbon dioxide and water are the products: they are formed by the reactions.

Energy is released during the reactions, but it is not a substance, so it is not shown among the products in the word equation.

Anaerobic respiration

Cells can release energy from nutrient molecules without using oxygen. They do this through a series of chemical reactions called anaerobic respiration. The released energy can be used by the cell.

Anaerobic respiration releases much less energy per glucose molecule than aerobic respiration, which uses oxygen. The products of anaerobic respiration depend on the cells involved.

Anaerobic respiration in yeast

In yeast cells, glucose is broken down to produce alcohol and carbon dioxide:

glucose→alcohol+carbon dioxide\text{glucose} \rightarrow \text{alcohol} + \text{carbon dioxide}

Anaerobic respiration in muscles

During vigorous exercise, muscle cells can release energy from glucose by anaerobic respiration. In these cells, glucose is broken down to produce lactic acid:

glucose→lactic acid\text{glucose} \rightarrow \text{lactic acid}

Notes for this section are being prepared.

Notes for this section are being prepared.