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?