35. Soil

How do animals obtain usable nitrogen for their biological processes?

Where do plants primarily obtain the nitrogen necessary for synthesizing amino acids and DNA?

What is the primary role of decomposers in the nitrogen cycle?

Which process is primarily responsible for returning nitrogen to the atmosphere in the nitrogen cycle?

For what essential biological purpose do plants and animals require nitrogen?

Why must atmospheric nitrogen ($N_2$) be 'fixed' before most organisms can use it, and which organisms are primarily responsible for this process?

Why do plants and animals need nitrogen?

How do animals obtain nitrogen for use in synthesizing proteins?

Why do organisms require nitrogen?

Why can't plants and animals use nitrogen (N_2) directly as it is found in the atmosphere?

Which biogeochemical cycle describes how nitrogen moves through an ecosystem?

Which type of organism is primarily responsible for converting atmospheric nitrogen ($N_2$) into a form usable by plants?

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

Which of the following is primarily responsible for capturing atmospheric nitrogen ($N_2$) and converting it into a biologically usable form during nitrogen fixation?

Nitrogen fixation is carried out primarily by which of the following?