7)What factors contribute to the electrochemical gradient? a) The two factors that affect the electrochemical gradient of the plasma membrane of a cell are the concentration gradient of chemicals across the plasma membrane; and the electrical gradient of variation in electrical charges across the plasma membrane. 8)What factors can increase the rate of diffusion? a) These five factors are: temperature, the steepness of the concentration gradient, mass of diffusing substance, surface area, and diffusion distance. 9)How does simple diffusion compare with facilitated diffusion?
a) Simple diffusion occurs when a molecule moves across the plasma membrane without any assistance, while facilitated diffusion requires the assistance of a membrane protein. 10)What is osmotic pressure? a) It is the pressure generated by the particles of a solute that are unable pass across a permeable membrane. 11)Distinguish among isotonic, hypotonic and hypertonic solutions. a) Isotonic solutions are solutions in which the volume in a cell is constant with the volume outside of cells, and so no change in cell shape/function occurs. Hypotonic solutions are solutions in which the solution a cell is in has a lower concentration of a solution than the cells internal solution, resulting in solutes leaving the cell and causing water molecules to enter the cells; resulting in bloating and possibly rupturing of the cell. Hypertonic solutions are solutions where the solution of the fluid surround a cell is greater than the cells internal solution, and so the cell removes water molecules and shrinks as it takes on more solute. 12)What is the key difference between active and passive processes? a) Active processes require the expending of energy to move a substance against it gradient, usually in the form of expending ATP; while a passive process does not require the cell to actively expend energy by allowing a substance to move with its gradient. 13)How do symporters and antiporters carry out their functions? a) Symporters and antiporters use what is known as secondary active transport to move a particle across the plasma membrane; they use the energy generated from the active transporting of a particle to move another particle with it. Symporters move two particles in the same directions, while antiporters move two particles in opposite directions of each other. 14)What are the sources of cellular energy for active transport? a) The most common source of energy for active transport is chemical energy gained through the hydrolysis of ATP. 15)In what ways are endocytosis and exocytosis similar and different? a) Exocytosis and endocytosis both rely on the plasma membrane to assist in the movement of vesicles in and out of cells; they use these vesicles to move important particles about. Exocytosis is the expelling of these materials however outside of the plasma membrane while endocytosis is the taking in of materials from either vesicles or particles that come into contact with the plasma membrane.
You've reached the end of your free preview.
Want to read all 42 pages?