The cells are producing carbon dioxide and water. By taking in oxygen, the one performing cellular respiration releases carbon dioxide into the air.
Predators and prey are both in a constant struggle for survival, foxes with bigger ears tend to catch more mice, and live longer, because of this, foxes with smaller ears don't live as long, pretty soon all foxes have larger ears. The same goes for prey, Mice with padded feet live longer due to the foxes having more trouble hearing them, pretty soon all mice have padded feet, and the cycle continues.
The optimal pH can be measured by looking at enzyme activity verses pH. Enzyme activity will increase up to a certain pH; above that pH, the enzyme activity will begin to fall.
Crosscutting concepts have application across all domains of science. As such, they are a way of linking the different domains of science. They include patterns; cause and effect; scale, proportion, and quantity; systems and system models; energy and matter; structure and function; and stability and change.
