35. Soil

What is the primary reason that plants and animals require nitrogen?

Which organisms are primarily responsible for transforming atmospheric nitrogen ($N_2$) into a form that is usable by plants?

How do humans primarily obtain the nitrogen necessary for building proteins and nucleic acids?

Members of which phylum establish a successful symbiotic relationship with the roots of trees for nitrogen fixation?

Which of the following molecules do plants primarily produce using nitrogen obtained through nitrogen fixation?

Which of the following best describes what happens during nitrogen fixation?

How does nitrogen fixed by bacteria ultimately become available to herbivores and carnivores in an ecosystem?

Which organisms are primarily responsible for transforming atmospheric nitrogen ($N_2$) into a form that is usable by plants?

After nitrogen is released from our bodies through waste or decomposition, which organisms are primarily responsible for incorporating that nitrogen back into the ecosystem?

Which of the following does NOT conduct nitrogen fixation?

In a diagram showing the root nodules of a leguminous plant, nitrogen-fixing bacteria are indicated by the letter(s) _____.

Which of the following is a way that nitrogen fixation can occur in nature?

Which of the following pathways indicates how nitrogen is added to the largest nitrogen reservoir, the atmosphere?

What is the role of nitrogen-fixing bacteria in the nitrogen cycle?

Bacteria in root nodules change nitrogen gas ($N_2$) into what form?