(b) : The reactions of Krebs' cycle were worked out by Sir Hans Kreb, hence the name Krebs' cycle. It involves many 3 -C compounds such as citric acid, cis-aconitic acid and iso-citric acid etc., so it is also called TCA cycle or tricarboxylic acid cycle. It involves formation of citric acid as its first product so it is called citric acid cycle. It involves production of 24 ATP molecules.