Physioex 8.0 Exercise 1

REVIEW SHEET EXERCISE 1 Cell Transport Mechanisms and Permeability 1. Match each of the definitions in Column A with the appropriate term in Column B. |Column A |Column B | |__E__ term used to describe a solution that has a lower |a. diffusion | |concentration of solutes compared to another solution |b. facilitated diffusion | | |c. smosis | |__G__ term used to describe a solution that has a higher |d. active transport | |concentration of solutes compared to another solution |e. hypotonic | | |f. isotonic | |__A__ the movement of molecules from an area of higher |g. ypertonic | |concentration to an area of lower concentration as a result of | | |random thermal motion | | | | | |__D__ the movement of molecules across a membrane that requires| | |the expenditure of cellular energy (ATP) | | | | | |__C__ the transport of water across a semipermeable membrane | | | | | |__F__ term used to describe two solutions that have the same | | |concentration of solutes relative to one another | | | | | |__B__ the movement of molecules across a selectively permeable | | |membrane with the aid of specialized transport proteins | | 2. What is the main difference between simple diffusion and facilitated diffusion?

Simple diffusion passes through a biological membrane and facilitated involves passing through selectively permeable membrane. 3. What is the main difference between facilitated diffusion and active transport? Active transportation requires the use of ATP and facilitated is passive using no energy. 4. In the “Simple Diffusion” experiment, which solute(s) passed through the MWCO 20 membrane? None of the substances passed through the MWCO 20 membrane. Why? They did not pass through because the solute mass was greater than twenty. 5. List three examples of passive transport mechanisms. Three examples include, simple diffusion, osmosis, and facilitated diffusion. 6. Describe the relationship of solute concentration to solvent concentration in osmosis.

The solute concentration is higher than the solvent. 7. What is the equation for Fick’s First Law of Diffusion? Jnet=dQs/dt=-DA(dc/dx) 8. In the mock dialysis activity, what was the only solute removed from the beaker representing the patient’s blood? Urea was the only solute removed to be removed. Why is it important that this solute be removed from diabetic patients? It must be removed because it will become toxic to body and cause death. 9. How can the concentration of water in a solution be decreased? The concentration can be decreased by adding solute. 10. Suppose that a membrane separates a solution of higher osmolarity and a solution of lower osmolarity.

To prevent osmotic flow of water across the membrane, pressure should be applied to which of the two solutions? Pressure should be applied to the higher osmolarity to block water from coming in. 11. What change in cell volume will occur when a cell is placed in a hypotonic solution? Water will move into the cell causing the cell to expand. 12. What change in cell volume will occur when a cell is placed in a hypertonic solution? Water will move out of the cell causing it to shrink. 13. By what mechanism does the active transport of sodium lead to osmotic flow of water across a membrane? Osmotic balance is used to add sodium ions outside the cell to draw out water otherwise, the cell would burst. 14.

If two solutions having different osmolarities are separated by a water-permeable membrane, will there be a change in the volume of the two compartments if the membrane is impermeable to solutes? It will result in a change, because water will flow from a region of high concentration to low until the osmolarities are equal. Will there be a change in the volume of the two compartments if the membrane is permeable to solutes? There will be no change because the solute will simultaneously diffuse from higher osmolarity solution to lower until equilibrium is reached. Explain your answers. Stabler, T. , Peterson, G. , Smith, L. & Lokuta, A. (2009). PhysioEx 8. 0 for human physiology: Lab simulations in physiology. Benjamin Cummings.