1. Which of the following statements regarding the general concepts of metabolism is true?
(A) once glucose is converted to pyruvate, there is no way to convert pyruvate back to glucose
(B) when triacylglycerols are used as fuel, only the fatty acids can be metabolized, the glycerol is a waste product
(C) all 20 common amino acids can be made from metabolites derived from the citric acid (or TCA) cycle
(D) the citric acid (or TCA) cycle is generally considered an anabolic pathway while gluconeogenesis is generally considered a catabolic pathway
(E) none of the above