Compare and contrast the mechanisms of getting material across the plasma membranes of cells. Tells me what the mechanisms are if they are active or passive transport, how do they function and give me an example of where you would find that mechanisms.

Materials get transported from the cell by some mechanisms such as Active Transport, Passive Transport, Diffusion, etc.

Explanation:

Active Transport :

It is a process by which, materials are transported from the extracellular membrane to the intracellular membrane with the help of ATP. It has a few types :  

Primary Active Transport :  

This system is standing upon the sodium-potassium pump. It moves out   Na⁺ from the cell and allows the entry of K⁺ into the cell. In this process ATP is a source of energy. E.g, Sodium-potassium pump.

Secondary Active Transport :

It is mainly standing upon Primary Active Transport. In this process, the main key point is the concentration gradient. There is already a concentration gradient set up by the primary active transport. This system uses that up and moves other substances against their own gradient concentration. E.g, assuming, there is a high concentration of sodium outside the cell,  if a route such as a channel or a carrier protein is open then sodium ions will move into the cell.  In this transport system, some cotransporters are used who move in the sodium ion into the sodium gradient.  

Passive transport :

It is a process by which, substances cross the plasma membrane without acquiring any energy from the cell. Here, no energy is needed because the substances are moving from higher concentration to its lower concentration. E.g, cell membrane or plasma membrane works as a permeable or semipermeable membrane.  

Diffusion :

It is the movement of a substance across a membrane, due to the concentration gradient, without any help from other molecules. E.g, movement of the gaseous molecule from cell to cell.