Class 11 NEET Biology Respiration In Plants Questions

(a) : When oxygen is not available ( anaerobic condition) yeast and some microbes convert pyruvic acid into ethyl alcohol. It is a two step process. In the first step pyruvic acid is decarboxylated to yield acetaldehyde and CO2.
Pyruvic acid is a 3 -C compound and acts as electron donor while acetaldehyde is the electron acceptor.
CH3COCOO−+H+→CH3CHO+CO2 ( pyruvic carboxylase)
In the second step acetaldehyde is reduced to ethyl alcohol by NADH ‌2 formed in the glycolysis.
CH3CHO+NADH+H+→C2H5OH+NAD+ (alcohol dehydrogenase)