Glossary

• Adenosine triphosphate = compounds consisting of an adenosine molecule bonded to three phosphate groups
• Carrier proteins = membrane protein that moves solutes across the membrane by creating conformational changes in the protein
• Concentration gradient = gradual difference in concentration of a dissolved substance between a region of high and low density
• Co-transport = transport of solute across a membrane from a region of low concentration of another solute to a region of high concentration for that solute
• Facilitated diffusion = transport of substances across a biological membrane from an area of high to low concentration
• Isotonic = solution having the same osmotic pressure as another solution
• Kinetic energy = energy of motion, movement of an object or subatomic particle
• Microvilli = finger-like membrane protrusions that increase the surface area of the cell
• Phospholipid = A lipid that contains a phosphate group and two fatty acids
• Plasmolysed = process of contraction or shrinkage of the protoplasm of a plant
• Plasmolysis = osmotic condition where 50% of the cells are plasmolysed
• Protein channels = proteins that allow the transport of specific substances across a cell membrane
• Protoplast = plant cells that have had their cell walls removed by treatment with a chemical
• Simple diffusion = the movement of molecules from an area of high concentration to an area of low concentration until an equilibrium is reached
• Sodium ions = acts as a critical intracellular messenger that regulates many cellular functions
• Sodium-potassium pump = sodium ions are pumped out of the cell
• Villi = small projections of the intestinal wall that increase the surface area for absorption
• Water potential = tendency of water to move from one area to another