Vitamin not required in TCA cycle ?

Ans. is 'd' i.e., Folic acid Four of the B vitamins are essential in the citric acid cycle : Riboflavin, in the form of flavin adenine dinucleotide (FAD), a cofactor for succinate dehydrogenase. Niacin, in the form of nicotinamide adenine dinucleotide (NAD) the electron acceptor for isocitrate dehydrogenase, a-ketoglutarate dehydrogenase, and malate dehydrogenase. Thiamine (vitamin B1), as thiamine diphosphate, the coenzyme for decarboxylation in a-ketoglutarate dehydrogenase reaction. Pantothenic acid, as pa of coenzyme A, the cofactor attached to "active" carboxylic acid residues such as acetyl-CoA and succinyl CoA.