Which of the following best describes the nitrogen cycle?

• A. The movement of water from the Earth's surface to the atmosphere and back again.
• B. The transfer of energy through a food chain from producers to consumers.
• C. The process by which carbon dioxide is absorbed by plants and converted into glucose.
• D. The process by which nitrogen is converted between its various chemical forms and circulated among the atmosphere, soil, and living organisms.

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the nitrogen cycle. The nitrogen cycle is a biogeochemical process that describes how nitrogen is converted into different chemical forms and moves through the atmosphere, soil, and living organisms.
2. Step 2: Recognize the key processes involved in the nitrogen cycle. These include nitrogen fixation (conversion of atmospheric nitrogen into ammonia), nitrification (conversion of ammonia into nitrites and nitrates), assimilation (uptake of nitrates by plants), ammonification (conversion of organic nitrogen into ammonia), and denitrification (conversion of nitrates back into atmospheric nitrogen).
3. Step 3: Compare the nitrogen cycle to the other options provided in the question. For example, the movement of water describes the water cycle, the transfer of energy through a food chain relates to energy flow in ecosystems, and the absorption of carbon dioxide by plants is part of the carbon cycle.
4. Step 4: Identify the correct description of the nitrogen cycle from the options. The correct answer is the process by which nitrogen is converted between its various chemical forms and circulated among the atmosphere, soil, and living organisms.
5. Step 5: Conclude by emphasizing the importance of the nitrogen cycle in maintaining ecosystem balance, as nitrogen is a critical element for the synthesis of proteins and nucleic acids in living organisms.