The main role of microorganisms in the biogeochemical cycles is to _______________.

A. Work in the decomposition of matter and in the recycling of nutrients necessary for the energy exchange in the biogeochemical cycles.

B. Circulate critical elements of living matter within the biogeochemical cycles.

C. Provide food necessary to supply energy for the biogeochemical cycles.

D. Generate gases as part of their digestion process, which will contribute to maintain equilibrium conditions in the biogeochemical cycles.

Answer:

Microorganisms in biogeochemical cycles work in the decomposition of matter and in the cycling of nutrients necessary for the energy exchange in the biogeochemical cycles. Biogeochemical processes transport nutrients across the ecosystem. A biogeochemical cycle is a circuit that allows a chemical entity to pass through an ecosystem's biotic and abiotic factors. It contains biotic factors, such as live organisms, as well as minerals, air, water, and chemicals. The species that reside in the decomposer trophic stage of the Earth's food system are crucial to the planet's survival. Microorganisms play an important role in a variety of environmental processes, including improving soil fertility. Soil microbes mediate biogeochemical cycling for the supply of soil mineral nutrients such as nitrogen, phosphorus, and sulfur, which are the most essential growth-promoting nutrients for plants.

Reference

Ciais, P., Sabine, C., Bala, G., Bopp, L., Brovkin, V., Canadell, J., ... & Thornton, P. (2014). Carbon and other biogeochemical cycles. In Climate change 2013: the physical science basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (pp. 465-570). Cambridge University Press. 

Morel, F. M., & Price, N. M. (2013). The biogeochemical cycles of trace metals in the oceans. Science, 300(5621), 944-947.