True, organisms take in nitrogen and carry out life processes.
Most enzymes do in fact work on a single substrate in most cases, this is because of the enzyme - substrate specificity. Certain reactant molecules acting as substrates can only fit in the "lock" of particular enzymes and undergo a conformational change and result in Unique products to be released after the reaction has occurred.
Explanation:
Classification systems function in order to organize a group of organisms into smaller groups according to some kind of logic. For example, the most used classifications system in biology is the phyllogenetic, which classifies living beings according to their evolutive affinity.
In the other hand, a dichotomous key is a "guide" used by biologists when they need to indentify an individual. It is organized in several steps regarding some key characteristics in order to guide you to which species/genus/family your individual belongs to. A dichotomous key never provides any kind of trustworthy phyllogenetic information, and should be understood only as a tool.
