What type of substance do plants make using nitrates?

• A. Carbohydrates
• B. Protein
• C. Lipids
• D. Nucleic acids

Answer: (B)

Nitrogen from nitrates is used to make amino acids, the building blocks of proteins. Plants absorb nitrates from the soil and convert them into forms that become amino acids like glutamine and glutamate; these amino acids are then linked together to form proteins. Because proteins depend on nitrogen, nitrates directly support protein synthesis, making proteins the best answer. Carbohydrates and lipids are built mainly from carbon, hydrogen, and oxygen and don’t require nitrates for their basic structures, while nucleic acids do contain nitrogen but are not produced directly from nitrates in the way proteins are.