The greater the surface area of a cell, the faster the cell can transport materials across its membrane because there is more area to absorb/excrete materials. We also want the surface area much higher than the volume of a cell. the more volume a cell has the slower the transport of diffusion will be. If the cell is smaller because it has a higher surface area than it does volume. Because of this larger SA:V ratio, smaller cells will transport materials faster.
The very function, or job of CELL MEMBRANES is to protect the cell from it's surroundings, or in other words, to keep it safe. It controls the movement of substances in and out of cells and organelles, like a guard watching for suspicious activity and protecting something.
The cell membrane itself is a thin, flexible layer around the cells of all living things. It separates the inside of the cells from the outside of the cells.
Um... neeeed details plz!