A population is all the organisms of the same species in a group, like humans. Population is different from a community in that a population is every organism of the species grouped as a whole, and a community is a certain number of organisms within the whole population. That may not make sense, but that’s as good as I can describe it.
This <span>statement should be classified as</span> a theory
The alveoli are lined with mucus and are surrounded by a network of blood capillaries. They have very thin walls for gases to be absorbed through. An individual air sac is called an alveolus. The layer of moisture in the alveoli allows gases to dissolve so that they can diffuse quickly.