What term describes a substance composed of carbon, hydrogen, and oxygen, such as sugar or starch?

The term that describes a substance composed of carbon, hydrogen, and oxygen, such as sugar or starch, is carbohydrate. Carbohydrates are organic compounds that serve as a major energy source for living organisms. They can be classified into simple carbohydrates, like sugars, and complex carbohydrates, such as starches, which are made up of long chains of sugar molecules.

In contrast, proteins are made from amino acids and primarily contain carbon, hydrogen, oxygen, and nitrogen, while lipids are fatty compounds that also include carbon and hydrogen, often with considerably fewer oxygen atoms compared to carbohydrates. Nucleic acids, such as DNA and RNA, are composed of nucleotides and contain carbon, hydrogen, oxygen, nitrogen, and phosphorus. Therefore, the specific combination of carbon, hydrogen, and oxygen in a ratio typical of carbohydrates is what distinguishes them as a separate class of biomolecules.