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. Carbohydrates and proteins produce less than half of this, at only four calories per gram.

Detailed explanation-2: -Energy-rich molecules such as glycogen and triglycerides store energy in the form of covalent chemical bonds. Cells synthesize such molecules and store them for later release of the energy.

Detailed explanation-3: -As FIGURE 3.1 shows, carbon-based molecules have three fundamental structures-straight chains, branched chains, and rings. All three types of molecules are the result of carbon’s ability to form four covalent bonds. Carbon chains can bond with carbon rings to form very large, complex molecules.

Detailed explanation-4: -Instead, they convert it into small, energy-rich molecules such as ATP and nicotinamide adenine dinucleotide (NADH), which can be used throughout the cell to power metabolism and construct new cellular components.