They form lactic acid which needs to be broken down as it is dangerous to the cel
The marrow in certain bones in your body create red blood cells, so eventually you get your blood back. The reason we need to give blood is for people, who lost to much blood to quickly to regenerate it in time to supply their body with oxygen.
The answer is Keystone. Keystone is a species in which others species in the ecosystem largely depend on, if the species was removed the ecosystem would change drastically.
The answer is A. populations, communities, and ecosystems
