So now that we've introduced the term theory in our previous lesson videos, here in this video we're going to talk about some basic theories of biology. And so really there are 3 basic theories of biology that your professors tend to want you all to know. And so notice down below in this table, we're going to show you each of these three theories and the concept that they apply to. And so the very first basic theory of biology that you should know is the cell theory, and the cell theory is pretty much saying that all living organisms are made up of cells and all cells come from preexisting cells, and so here we have a little image of a cell. Now once again recall that theories are really just broad hypotheses. And so, we can tell that it's broad here because it includes this word, all.
Now the second theory that you should be familiar with is the homeostasis theory, and the homeostasis theory pretty much says that all living organisms are going to be able to maintain a relatively consistent internal environment. And so here what we're showing you is a little picture of a person sweating in the hot sun since sweating is a mechanism that helps to maintain homeostasis. But really all living organisms have this ability to maintain relatively consistent internal environments. And once again, we can tell that this is broad because it includes the word all again.
Now the 3rd and final basic theory of biology that you should be familiar with is the theory of evolution. Now the theory of evolution does not say that evolution itself is a theory. Instead, the theory of evolution says that all living organisms evolved from a single common ancestor. And so here what we have is a little image that's used commonly to represent evolution. But the idea here is that, once again, theories can never be proven to be true. Instead, there's a large body of evidence that supports the theory. But once again, the theories will always remain falsifiable, which means that they can be proven to be false moving forward in the future. But once again, they will never be proven to be true.
And so there is quite a lot of evidence that suggests, and supports all three of these theories. But for now, this here concludes the basic theories of biology that you should be familiar with, and I'll see you guys in our next video.