Question

Describe how animals produce energy in aerobic and anaerobic conditions.

Answer 1

Animals primarily produce energy by metabolism of glucose. Respiration is the process of releasing energy from the breakdown of glucose. Respiration takes place in every living cell, all of the time and all cells need to respire in order to produce the energy that they require. It can be aerobic or anerobic. Anerobic metabolism is usually employed by prokaryotes and in skeletal muscles in eukaryotes.

Anerobic respiration in muscles :

Anaerobic respiration happens in muscles during hard exercise:

glucose → lactic acid + energy

C6H12O6 → 2C3H6O3 + 120kJ/mol

Glucose is not completely broken down, so much less energy is released than during aerobic respiration. There is a build-up of lactic acid in the muscles during vigorous exercise. The lactic acid needs to be oxidised to carbon dioxide and water later.

Anerobic respiration in plant cells and prokaryotes :

Anaerobic respiration also happens in plant cells and some microorganisms. Anaerobic respiration in yeast is used during brewing and bread-making:

glucose → ethanol + carbon dioxide

C6H12O6 → 2C2H5OH + 2C02

Aerobic Respiration

Aerobic respiration needs oxygen. It is the release of a relatively large amount of energy in cells by the breakdown of food substances in the presence of oxygen:

glucose + oxygen → carbon dioxide + water + energy

C6H12O6 + 6O2 = 6CO2 + 6H2O + 2900 kJ/mol

Approximately 2900 kJ of energy is released when one mole of glucose is broken down. The released energy is used to make a special energy molecule called Adenosine triphosphate (ATP).