Under natural conditions, most populations will stabilize at a level known as the carrying capacity of the ecosystem<span>. The carrying capacity is the maximum </span>number of organisms that an ecosystem can support<span> on a continued basis.</span>
The main difference between the organisms are the uses of the appendage and the size and number of certain bones. The human arm is used for a variety of functions while the lizard's and the cat's are used for walking an climbing, the whale's for swimming, the frog's for support and the bird's and the bat's for flying.
Cell membranes protect and organize cells. All cells have an outer plasma membrane that regulates not only what enters the cell, but also how much of any given substance comes in. Unlike prokaryotes, eukaryotic cells also possess internal membranes that encase their organelles and control the exchange of essential cell components. Both types of membranes have a specialized structure that facilitates their gatekeeping function.
