The dominant ones. Whatever has been gained through evolution in adaptation to their specific environment.
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.
<span><span>All cells have a plasma membrane, ribosomes, cytoplasm, and DNA.
</span>Prokaryotic cells lack a nucleus and membrane-bound structures.
<span>Eukaryotic cells have a nucleus and membrane-bound structures called organelles.</span></span>
