Biosynthetic integration is a major subject in biochemistry, but in Bio 101, the ideas are typically only hinted at, not typically well developed. The MCAT puts itself somewhere in the middle, not so hard that someone who has not had biochemistry can complain, but a bit harder than your average general biology course. The exam often discusses sophisticated concepts in a passage, but asks simple questions This is so important to understand this for your test-taking psychology. Never let an MCAT passage knock the wind out of you. If the passage is really hard, that just means the questions are going to be really basic. Such passages are a cue for you to grip down and listen to the voice of the passage, not to panic that you might have forgotten to study something important.

Back to carbohydrates as biosynthetic precursors. Here is what I wanted to say: The products of glycolysis and the subsequent decarboxylization of pyruvate, acetyl coenzyme A, may not always be utilized for energy production in the citric acid cycle. They can also serve a precursor in biosynthesis. Several amino acids and many lipids are among the products of biosynthesis from the acetate portion of acetyl coA for example.