Benthos live in the benthic zone. The benthic zone is the lowest level in a body of water. Bentho organisms include things such as crustaceans and polychaetes
Enzymes lower the activation energy of a chemical reaction.
Asymmetry is the lack of symmetry.
If you are adding something to the water the concentration of water would drop, as it would start off as 100% water but then with the addition of another substance it would change that from 100% free to x% free, due to the water dissolving the substance.
