Question

The process of cellular respiration in the absence of oxygen is called as

• A. Krebs Cycle
• B. Electron transport chain
• C. Fermentation
• D. Glycolysis
• E. Calvin cycle

Answer 1

The correct option is C Fermentation

Aerobic respiration is breakdown of sugar/other food substances in presence of oxygen to released energy. It includes glycolysis, Kreb cycle and electron transport chain. Glycolysis and Kreb cycle produce reducing compounds NADH, FADH${}_2$ which are then oxidized in presence of oxygen by the process of chemiosmosis and reduce oxygen to water. Fermentation is incomplete oxidation of food substances into alcohol and lactic acid with small amount of energy being released. Both lactic acid and ethanol fermentation do not use oxygen as electron acceptor. Calvin cycle is fixation of atmospheric carbon dioxide into organic compounds; it makes the dark reaction of photosythesis. This makes option C correct.