Questions: Monosaccharides are the building blocks of: * nucleic acids carbohydrates lipids proteins

The answer is the second one: carbohydrates.

Explanation for each option:

1. Nucleic acids: Incorrect. Nucleic acids are composed of nucleotides, which consist of a sugar, a phosphate group, and a nitrogenous base.
2. Carbohydrates: Correct. Monosaccharides are the simplest form of carbohydrates and serve as the building blocks for more complex carbohydrates like disaccharides and polysaccharides.
3. Lipids: Incorrect. Lipids are composed of fatty acids and glycerol, not monosaccharides.
4. Proteins: Incorrect. Proteins are made up of amino acids, not monosaccharides.

Summary: Monosaccharides are the building blocks of carbohydrates.