Diffusion Review Worksheet Essay Example for Free

Diffusion Review Worksheet Essay 1. Define diffusion and what causes it to occur? The action of spreading the light from a light source evenly so as to reduce glare and harsh shadows. Diffusion is caused when entities are small and moving in molecules. They collide because they are moving at a random pace. The temperature causes diffusion. 2. Define the terms hypertonic, hypotonic, and isotonic solution. * Hypertonic: Having increased pressure or tone, in particular. * Hypotonic: Having reduced pressure or tone, in particular. * Isotonic solution: a solution having the same osmotic pressure 3. Explain the similarities and differences between diffusion and osmosis. Both are the movement of a substance from an area of high concentration to an area of low concentration. But osmosis is the movement of water through a cell membrane. 4. Define Turgor pressure ( also known as osmotic pressure). The pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis, often used to express the concentration of the solution 5. What occurs when plasmolysis takes place? The cells shrink and shiver. 6. Define the terms endocytosis and exocytosis . * Endocytosis: the taking in of matter by a living cell by its membrane to form a vacuole. * Exocytosis: Large molecules that are manufactured in the cell are released through the cell membrane. 7. Name the two processes that occur during endocytosis. 8. What are the differences between active and passive transport? * Requires energy or ATP * Doesn’t require energy, moves high to low concentration 9. Define facilitated diffusion. * The passage of both materials aided by both a concentration gradient and by a transport protein. 10. What is a carrier protein? What is its function? * can change shape to move material from one side of the membrane to the other 11. What statement describes the movement of molecules from an area of low concentration to an area of high concentration? * 12. What does the term semipermeable (or selectively permeable) membrane mean? * Small molecules and larger hydrophilic molecules move through easily. * Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own. 13. What happens to the water in a cell placed in a hypertonic solution? * Water is moving out. 14. What happens to a cell placed in a hypotonic solution * It shrinks 15. Define the following terms: * Concentration gradient: a difference in the concentration of a substance across a distance * Diffusion: the movement of particles from regions of higher density to regions of lower density * Equilibrium: in biology, a state that exists when the concentration of a substance is the same throughout a space * Osmosis: the diffusion of water or another solvent from a more dilute solution (of a solute) to a more concentrated solution (of the solute) through a membrane that is permeable to the solvent * Phospholipid: a lipid that contains phosphorus and that is a structural component in cell membranes * carrier protein: a protein that transports substances across a cell membrane * Receptor protein: a protein that binds specific signal molecules, which causes the cell to respond * lipid bilayer: the basic structure of a biological membrane, composed of two layers of phospholipids * sodium-potassium pump: a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell * second messenger: a molecule that is generated when a specific substance attaches to a receptor on the outside of a cell membrane, which produces a change in cellular function * signal: anything that serves to direct, guide, or warn