Final answer:
A. Cholesterol is not a carbohydrate; it is a lipid, a class of macromolecules distinct from carbohydrates. Carbohydrates are made up of sugar molecules, and include substances like starches and cellulose, whereas cholesterol is a steroid involved in cellular structure and hormone production.
Step-by-step explanation:
The correct answer to the question Which of the following is not a carbohydrate? is A. Cholesterol. Carbohydrates are a class of biological macromolecules that include sugars, starches, and cellulose, all of which are made up of carbon, hydrogen, and oxygen with a general formula CH2O. They are classified as monosaccharides (single sugar units like glucose), disaccharides (two sugar units like sucrose), or polysaccharides (many sugar units like starch and cellulose).
Cholesterol, on the other hand, is not a carbohydrate but a lipid, specifically a steroid. It's an important component of cell membranes and a precursor to steroid hormones but has a completely different structure from carbohydrates. Cellulose and starch are examples of polysaccharides, which are complex carbohydrates made up of long chains of glucose monomers. The function of cellulose is to provide structural support to plant cell walls, whereas starch is the storage form of glucose in plants.