What class of macromolecules includes organic compounds consisting of carbon, hydrogen, and oxygen in a typical ratio of 1:2:1?

The correct answer is carbohydrates because they are organic compounds that typically consist of carbon, hydrogen, and oxygen in a ratio of 1:2:1. This specific ratio is characteristic of monosaccharides, which are the simplest form of carbohydrates. For example, glucose, a common monosaccharide, has the formula C6H12O6, clearly demonstrating this 1:2:1 ratio.

Carbohydrates serve as a primary source of energy for many organisms and play crucial roles in various biological processes, such as cellular structure and signaling. They can also exist in more complex forms, like disaccharides (two sugar units) and polysaccharides (many sugar units). Their structural diversity and functional roles in biology highlight their importance.

In contrast, proteins are made up of amino acids and contain elements such as nitrogen. Lipids are primarily composed of fatty acids and glycerol, and they do not follow the same ratio of carbon, hydrogen, and oxygen as carbohydrates. Nucleic acids, such as DNA and RNA, consist of nucleotides and also contain nitrogen and phosphorus, rather than adhering to the carbohydrate composition. This understanding underscores why carbohydrates are identified with the 1:2:1 ratio of their molecular constituents.