Question

Formation of ATP in respiration is called
A. Photophosphorylation
B. Substrate phosphorylation
C. Oxidative phosphorylation
D. Phosphorylation

Answer 1

Adenosine triphosphate also known as ATP is an organic compound that provides energy to living organisms by fuelling many processes in living cells, e.g. contraction of muscles, propagation of the nerve impulses, dissolution of the condensate, and chemical synthesis of various compounds in the body.

Complete answer:
• ATP’s are formed in the mitochondria.
• The breakdown of glucose in the presence of oxygen (respiratory breakdown) is an oxidative process.
• It involves several intermediates such as Pyruvic acid, Isocitric acid, Succinic acid, and Oxalic acid are oxidized.
• 2 Hydrogen is released in every oxidation step which goes to reduce various coenzymes i.e. NAD+ and FAD.
• These reduced coenzymes (NAD+ and FAD) that are released in the glycolysis and Krebs cycle reduce oxygen to water. The transfer of H+ and e- from NADH + H+ or FADH2 to oxygen is not a simple process and the direct transfer is not possible.
•This arrangement of electron transporters establishes the electron transport framework. The electron transport continues from transporters that have low redox potential to those having high redox potential. The electron transport down to the energy angle through the electron transport framework prompts the development of ATP from ADP and inorganic phosphate. This is called oxidative phosphorylation.
So, the formation of ATP is called Oxidative phosphorylation.

Hence, the correct answer is option (C).

Additional information:
Other terms-

Photophosphorylation occurs in the chloroplasts of cells, in the thylakoid membranes. It involves light-dependent reactions, light is absorbed by chlorophyll and other pigment molecules.
Substrate phosphorylation involves the conversion of ADP to ATP.
Phosphorylation-It involves the addition of Phosphate to the desired compound.

Note: ATP is produced from the ADP and inorganic phosphate within the electron transport chain when the electrons pass from one carrier to another through the four complexes and the electrons are coupled to ATP synthetase which is the fifth complex where ATP synthesis takes place.