AP BIOLOGY

Detailed explanation-1: -Pyruvate-three carbons-is converted to acetyl CoA, a two-carbon molecule attached to coenzyme A . A molecule of coenzyme A is a necessary reactant for this reaction, which releases a molecule of carbon dioxide and reduces a NAD+ to NADH.

Detailed explanation-2: -In the second reaction of the Krebs cycle, the isomerisation of citrate to isocitrate takes place. As an intermediate, cis-aconitate is formed. Therefore, it is a two-step reaction sequence.

Detailed explanation-3: -Pyruvate, derived from glycolysis, is firstly converted into acetyl-CoA (2-C) which is subsequently condensed with oxaloacetate (4-C) to form the 6-C compound citrate. This is cycled back to oxaloacetate via a series of reactions which form CO2 (as a waste product) as well as NADH and FADH.

Detailed explanation-4: -Overall, glycolysis converts one six-carbon molecule of glucose into two three-carbon molecules of pyruvate.

Detailed explanation-5: -Krebs cycle produces the following: Two molecules of carbon dioxide are given off. One molecule of ATP is formed. Three molecules of NADH are produced.