Basically because the flu shot is a stream of the flu. And when your body gets injected with it. It helps your body to become immune or able to fight the flu off quickly because you have had a little of the flu in you already.
I hope that made sense.... <span />
If natural selection changes then the phenotypes within a population changes over time because natural selection acts on phenotypes instead of genotypes .
The following that is a characteristic that could be applied to both living and nonliving things can contain mostly carbon, hydrogen, oxygen, and nitrogen.
