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The energy-releasing metabolic process in which substrate is oxidised without an external electron acceptor is called
A
Photorespiration
B
Glycolysis
C
Fermentation
D
Aerobic respiration
Detailed Solution
In aerobic respiration the electrons removed from the substrate are finally passed to an external electron acceptor, molecular oxygen.
In fermentation there is no external electron acceptor: glucose is only partially oxidised to pyruvic acid, and the NADH produced is re-oxidised by transferring its electrons to an internal organic molecule derived from the substrate itself.
In alcoholic fermentation acetaldehyde is reduced to ethanol; in lactic acid fermentation pyruvic acid is reduced to lactic acid.
Only a small amount of energy is released (net gain of 2 ATP per glucose).
Glycolysis by itself only produces pyruvate and NADH; photorespiration consumes energy.
Hence the process is fermentation.
In fermentation there is no external electron acceptor: glucose is only partially oxidised to pyruvic acid, and the NADH produced is re-oxidised by transferring its electrons to an internal organic molecule derived from the substrate itself.
In alcoholic fermentation acetaldehyde is reduced to ethanol; in lactic acid fermentation pyruvic acid is reduced to lactic acid.
Only a small amount of energy is released (net gain of 2 ATP per glucose).
Glycolysis by itself only produces pyruvate and NADH; photorespiration consumes energy.
Hence the process is fermentation.