Provide definitions/explanations for the following terms:
$(1)$ Biological Nitrogen Fixation
$(2)$ Root Nodules

(N/A) $(1)$ The process of reduction of atmospheric nitrogen $(N_2)$ into ammonia $(NH_3)$ by living organisms is known as biological nitrogen fixation.
$(2)$ Root nodules are small,rounded outgrowths or swellings found on the roots of leguminous plants,which house nitrogen-fixing bacteria such as $Rhizobium$.