Describe and name three stages of cellular respiration that aerobic organisms use to obtain energy from glucose.

Explanation

Stages of aerobic respiration :
(a) Glycolysis (Glucose splitting) :
(i) It is the breakdown of one molecule of glucose ( 6 carbon) into two molecules of pyruvic acid (3 carbon).
(ii) It takes place in cytoplasm of the cell.
(b) Krebs Cycle :
(i) This cycle occurs in mitochondrial matrix.
(ii) At the end of glycolysis, 2 molecules of pyruvic acid enter into mitochondria.
The oxidation of pyruvic acid into `CO_2` and water takes place through this cycle.
(iv) It is also called Tricarboxylic Acid Cycle (TCA).
(c ) Electron Transport Chain :
(i) This is accomplished through a system of electron carrier complex called elctron transport chain (ETC) located on the inner membrane of the mitochondria.
(ii) `NADH_2 and FADH_2` molecules formed during glycolysis and Krebs cycle are oxidised to `NAD^(+) and FAD^(+)` to release the energy via electrons.
(iii) The electrons, as they move through the system, release energy which is trapped by ADP to synthesize ATP. This is called oxidative phosphorylation.
(iv) In this process, `O_2` the ultimate acceptor of electrons gets reduced to water.