AP BIOLOGY

Detailed explanation-1: -There are four classes of biological molecules: fats, carbohydrates, proteins, and nucleic acids. Of these, fats produce the most energy per gram at a whopping nine calories per gram.

Detailed explanation-2: -Each fatty acid molecule produces many acetyl CoA molecules (whereas glucose yields two), so much more ATP can be generated from a single fatty acid molecule than one glucose molecule.

Detailed explanation-3: -When compared to other macronutrient classes (carbohydrates and protein), fatty acids yield the most ATP on an energy per gram basis, when they are completely oxidized to CO2 and water by beta oxidation and the citric acid cycle.

Detailed explanation-4: -Fats: Triglycerides make up more ATPs because they have three fatty acid tails connected to glycerol and they give additional energy. Glycerol can be transformed to glyceraldehyde-3-phosphate, a glycolysis intermediate, and then used to complete the cellular respiration breakdown cycle.