Maybe immune system and respiratory system
Having more then one independent variable will give unreliable results. Hope this helps
The polluted bacteria and algae interacts with fish and other aquatic wildlife, so they will be negatively impacted by that relationship in this case.
Although nitrogen gas makes up 78% of the atmosphere, we can't use it because nitrogen atoms must be broken apart first before. This nitrogen is very much packed and bonded with its atoms and would be useless to use since it can't be used for plants.
A large class of molecules is called a macromolecule.
