1: When the concentration of a substance is the same throughout a space, the substance is a: equilibrium 2: If a cell swells when place in a solution a: hypertonic 3: The following process allows the cell to dispose of wastes? 4: The diffusion of water through a selectively permeable membrane is called Osmosis 5: Identify each pairs of terms, and explain the difference in their meanings a: diffusion, equilibrium diffusion is when a substance moves from a high concentration to a lower one, when the diffusion is equal in space, equilibrium is achieved b: receptor protein, carrier protein A receptor protein is a protein that binds to a specific signal signal molecule, enabling the cell to respond to the signal. Carrier proteins bind to a specific substance so they can carry them across a cell membrane. c: endocytosis, exocytosis Endocytosis is the movement of a substance into a cell by a vesicle. Exocytosis is the movement of a substance out of a cell by a vesicle. 5: active transport. passive transport Passive transport is the movement of substances across the cell membrane without the use of energy by the cell. Active transport is the movement of a substance against the concentration gradient of the substance. Active transport requires cell energy. An ion channel is a transport protein with a polar pore which ions can pass through. The diffusion of ions through ion channels is a form of passive transport because the ions move down their concentration gradients, requiring no energy by the cell.