Cellular respiration

In the syllabus and the exam

Cellular respiration is presented as the general umbrella process before the syllabus splits it into aerobic and anaerobic pathways, and candidates need to state its overall word equation (glucose combining with oxygen to release carbon dioxide, water and energy, or glucose alone releasing a smaller amount of energy without oxygen) and identify that it occurs continuously in the mitochondria of every living cell, not only during physical exercise. A frequently tested idea is that cellular respiration is not the same as breathing (the physical movement of air into and out of the lungs); breathing is a mechanical process that supplies the oxygen and removes the carbon dioxide involved in cellular respiration, but the actual chemical release of energy from glucose happens inside cells, a distinction examiners deliberately probe with questions asking candidates to explain the difference in their own words. A common error is describing cellular respiration as only occurring in the lungs or only during exercise, when in fact it takes place in every living cell around the clock to release the energy needed for all life processes, including at rest. Candidates should also be able to state that the energy released by cellular respiration is stored in a usable form as ATP, which then powers processes such as active transport, muscle contraction and protein synthesis throughout the body. Candidates are also expected to know that cellular respiration and photosynthesis are, in a sense, opposite processes in terms of their overall reactants and products, and structured questions sometimes ask candidates to compare the two word equations side by side to check this understanding.

Example

Every living cell, from a bacterium to a human muscle cell, carries out cellular respiration continuously, breaking down glucose to release the energy needed to power its activities.

Related terms

Aerobic respirationMetabolism

Source:SRC-DSKP-EN