Biogeochemical cycles are crucial to ecosystem function because _____.

• A. they prevent the loss of energy from ecosystems
• B. they eliminate the need for decomposers in ecosystems
• C. they increase the rate of photosynthesis in all plants
• D. they recycle essential nutrients, allowing them to be reused by living organisms

Answer: (D)

Verified step by step guidance

1. Understand the concept of biogeochemical cycles: These are natural pathways through which essential elements like carbon, nitrogen, phosphorus, and water circulate through the biotic (living) and abiotic (non-living) components of ecosystems.
2. Recognize the importance of nutrient recycling: Biogeochemical cycles ensure that essential nutrients are not lost from the ecosystem but are instead reused by organisms, maintaining ecosystem stability and function.
3. Eliminate incorrect options: (1) Biogeochemical cycles do not prevent energy loss because energy flows in one direction and is not recycled. (2) They do not eliminate the need for decomposers; decomposers play a key role in breaking down organic matter to release nutrients. (3) They do not directly increase the rate of photosynthesis in all plants.
4. Identify the correct function: The primary role of biogeochemical cycles is to recycle essential nutrients, such as carbon, nitrogen, and phosphorus, so they can be reused by living organisms.
5. Conclude that the correct answer is: 'They recycle essential nutrients, allowing them to be reused by living organisms.' This aligns with the fundamental purpose of biogeochemical cycles in ecosystems.