Respiration releases energy for use in life processes. There are two types of respiration, aerobic (uses oxygen) and anaerobic (does not use oxygen). Respiration can produce useful products that have uses in a range of industries.

Energy from respiration.

Glucose is produced during photosynthesis. This energy is released from cells by a series of chemical reactions. This process is called respiration. Energy from respiration is used in reactions that produce different molecules. Examples of these molecules include starch and cellulose, which are polymers of glucose required by plant cells.

Energy released by respiration is allowing this sportsperson to perform a number of actions such as moving, growing and repairing any damaged tissue.

Aerobic respiration.

Respiration is not the same thing as breathing. Breathing is more properly called ventilation. Instead, respiration is a chemical process in which energy is released from food substances, such as glucose - a sugar.

Aerobic respiration needs oxygen to work. Most of the chemical reactions involved in the process happen in tiny objects inside the cell cytoplasm, called mitochondria.

This is the equation for aerobic respiration:

glucose + oxygen → carbon dioxide + water (+ energy).

The energy released by respiration is used to make large molecules from smaller ones. In plants, for example, sugars, nitrates and other nutrients are converted into amino acids. Amino acids can then join together to make proteins. The energy is also used:

• To allow muscles to contract in animals.
• To maintain a constant body temperature in birds and mammals.

Aerobic respiration - Higher tier.

For the higher paper you must recall the symbol equation for aerobic respiration:

C₆H₁₂O₆ + 6O₂ → 6C O₂ + 6H₂O.

Anaerobic respiration.

Anaerobic respiration is a type of respiration that does not use oxygen. It is used when there is not enough oxygen for aerobic respiration. It can be summarised by the following equation:

glucose…