IB Biology C1.2 Notes

Remember that cell respiration is the process by which a cell releases energy, in the form of ATP, from its organic compounds. You learned that it is divided into two types: aerobic and anaerobic. In this topic, you will learn about the specific reactions that occur in each type. To summarize:

1. In anaerobic respiration, only glycolysis occurs.
2. In aerobic respiration, glycolysis is followed by the link reaction, Krebs cycle, and oxidative phosphorylation. This ends up producing around 34 more ATP molecules.

Additionally, to understand what occurs in the reactions it is important to understand two terms: oxidation and reduction.

1. Oxidation is the loss of electrons.
2. Reduction is the gain of electrons.

However, it is sometimes difficult to see how electrons are transferred, so two alternate definitions can be used:

1. Oxidation is the gain of oxygen or the loss of hydrogen.
2. Reduction is the loss of oxygen or the gain of hydrogen.