What are carbohydrates?
Carbohydrates are a class of organic compound often used for energy, but are also important structurally. A carbohydrate can be a polymer itself, like starch, or it might be a monomer, like glucose.
A single unit or monomer of a carbohydrates is called a monosaccharide. These are often ring-shaped and include molecules like glucose and fructose. Also, they tend to have the formula
If you put two monosaccharides together, you have a disaccharide. A common example is sucrose, which is table sugar. It consists of glucose and fructose connected together. Here's sucrose:
More than two monosaccharides is usually called a polysaccharide. Examples of polysaccharides include cellulose and starch. Starch is the main way plants store energy and you might be aware of various foods that are high in starch, like potatoes, rice, and grains. Starch is made of lots and lots of glucose molecules connected together.
So, the term "carbohydrate" can refer to any of these molecules: monosaccharides, disaccharides, and polysaccharides. So not all carbs are polymers, but some are.