Which of the following statements correctly describes nitrogen and its role as a plant nutrient?

• A. Nitrogen is an essential macronutrient required for the synthesis of amino acids and nucleic acids in plants.
• B. Nitrogen is primarily absorbed by plants in the form of elemental nitrogen (\(N_2\)) from the atmosphere.
• C. Nitrogen is a micronutrient that plants require in very small amounts.
• D. Nitrogen is not involved in the formation of chlorophyll in plants.

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the role of nitrogen in plants. Nitrogen is a macronutrient, meaning it is required in large amounts for plant growth and development. It is essential for synthesizing amino acids, which are the building blocks of proteins, and nucleic acids, which are vital for genetic material (DNA and RNA).
2. Step 2: Clarify how plants absorb nitrogen. Plants cannot directly use elemental nitrogen (\(N_2\)) from the atmosphere. Instead, they absorb nitrogen primarily in the form of nitrate (\(NO_3^-\)) and ammonium (\(NH_4^+\)) ions from the soil, which are products of nitrogen fixation and decomposition processes.
3. Step 3: Differentiate between macronutrients and micronutrients. Macronutrients like nitrogen are required in large quantities, whereas micronutrients are needed in trace amounts. Nitrogen is not a micronutrient; it is a macronutrient essential for plant growth.
4. Step 4: Address the role of nitrogen in chlorophyll formation. Nitrogen is a critical component of chlorophyll, the pigment responsible for photosynthesis in plants. Without sufficient nitrogen, plants cannot produce enough chlorophyll, leading to poor growth and yellowing leaves (chlorosis).
5. Step 5: Evaluate the statements provided in the problem. Use the information from the previous steps to identify the correct statement: 'Nitrogen is an essential macronutrient required for the synthesis of amino acids and nucleic acids in plants.' The other statements are incorrect based on the explanations provided.