3NGS_MEcology_Biogeochemical Cycles

What is the primary pathway through which phosphorus enters terrestrial ecosystems in the phosphorus cycle?

• Weathering of rocks

• Atmospheric deposition

• Rainfall

• Volcanic eruptions

• None of the choices

In the nitrogen cycle, which process converts ammonia into atmospheric nitrogen gas (N2) under anoxic conditions?

• Denitrification

• Nitrification

• Nitrogen fixation

• Ammonification

• None of the choices

The following are examples of physical transformations except:

• Dissolution

• Volatilization

• Precipitation

• Fixation

• None of the choices

Which of the following element is cycled extensively in the biosphere?

• C

• O

• Fe

• P

• S

Which of the following organisms can convert ammonia to nitrite?

• Azotobacter

• Nitrosococcus

• Nitrobacter

• Pseudomonas

• None of the choices

Answer explanation

Nitrification involves two distinct groups of bacteria: those that convert ammonia to nitrites (such as Nitrosomonas, Nitrosospira, Nitrosococcus, and Nitrosolobus) and those that convert nitrites, which are toxic to plants, into nitrates (Nitrobacter, Nitrospina, and Nitrococcus).

References:

Samocha, T. M., & Prangnell, D. I. (2019). System treatment and preparation. In Elsevier eBooks (pp. 119–131). https://doi.org/10.1016/b978-0-12-818040-2.00006-x

https://www.sciencefacts.net/nitrification.html