MODEL PAPER 5 — BIOLOGY STD 11 Science — Question

• Oxidative phosphorylation is a metabolic pathway that uses energy released by the oxidation of nutrients to produce
adenosine triphosphate (ATP).
• Although the many forms of life on earth use a range of different nutrients, almost all carry out oxidative phosphorylation to produce ATP, the molecule that supplies energy to metabolism.
• This pathway is an efficient way of releasing energy, compared to alternative fermentation processes such as anaerobic glycolysis.
• During oxidative phosphorylation, electrons are transferred from electron donors to electron acceptors such as oxygen, in redox reactions. These redox reactions release energy, which is used to form ATP.
• In eukaryotes, these redox reactions are carried out by a series of protein complexes within mitochondria, whereas, in prokaryotes, these proteins are located in the cells' inner membranes. These linked sets of enzymes are called electron transport chains.