Macronutrients are defined as elements required in relatively large amounts for growth and survival.

• A. True
• B. False
• C. Only in plants
• D. They are used only for energy

Answer: (A)

Macronutrients are the elements cells must obtain in relatively large amounts to build biomass and carry out metabolism. For microbes, major macronutrients include carbon, nitrogen, oxygen, hydrogen, phosphorus, and sulfur, which form essential biomolecules like proteins, nucleic acids, lipids, and carbohydrates. In addition, essential inorganic ions such as potassium, magnesium, and calcium support enzyme activity and maintain cell stability. Because these elements are needed in larger quantities, they’re categorized as macronutrients, while micronutrients are required only in trace amounts as cofactors. The statement is true, and it’s important to note that macronutrients aren’t used only for energy—many also serve as building blocks and enzyme cofactors. This requirement applies broadly, not just to plants.