Sugars are a type of carbohydrate typically made up of hydrogen, carbon, and oxygen. The hydrogen:oxygen ratio is typically 2:1. Which of the following statements explains how carbohydrates function as a stored form of energy?

(A) Excess glucose is stored as glycogen in muscles and the liver.
(B) Glucose is broken down during photosynthesis to act as an energy source.
(C) Glycerol is released into the bloodstream when stored fat is used as an energy source.
(D) Glucagon is a hormone that stores excess energy in the pancreas.

There are four major types of macromolecules, and each type has specific functions and characteristics. Proteins are made of amino acids and function as enzymes, receptors, hormones, signals, and receptors. Lipids are made of fatty acids and glycerol and function as membrane components and energy storage. Carbohydrates are made of monosaccharides and function as energy storage. Nucleic acids are made of nucleotides and provide genetic information for organisms.