The term posterior teeth defines the teeth in the back of our mouths with their flat surfaces to crush the food. There are two kinds and they are called molars and premolars. The proximal contact of posterior teeth refers to these teeth being in contact with each other's surface areas constantly which result in erosion over time. The answer given in option C, decreased lenght of anatomic crowns is true because anatomic crown is the part of the teeth that is visible and covered with enamel so the constant contact affects this area and causes it to wear in time.
E.Coli would be a good model organism to study how the cell membrane controls movement of substances in and out of cells because it a eubacteria .Eubacteria characteristics include the ability to allow the movement of molecules across its membrane once a proton gradient is established , The membrane also has permeability enhancing properties that allow for the easy movement of substances.
