48-05-membrane_transport.doc 5.13 Bio 48 - Human Physiology Rev: 2/2/11 5 Name: Membrane Transport LAB REPORT / QUESTIONS Before you begin: 1) Prepare and attach a graph of Distance vs Time for Exercise A - Osmosis Across an Artificial Semi-permeable Membrane. 2) Prepare and attach a graph of Distance vs Time for Exercise C - Simple Diffusion (combine averaged data for temperature, diffusion medium & molecular weight effects on one graph). Note: you can access the entire class data set and preliminary graphs from the course web page. To prepare your graph you may elect to isolate your individual groups data and/or use averaged class data to prepare your graph. If averaging data you may need to exclude some data sets that are clearly in error (use caution not to exclude valid data). Graphs may be hand prepared or prepared using Excel. All graphs must be clearly titled and labeled. Exercise A - Osmosis Across An Artificial Semi-Permeable Membrane 1. Define osmosis. What factors are required for osmosis to take place? 2. Define osmotic pressure. 3. Which solution will exert the greatest osmotic pressure: 20% sucrose or 40% sucrose? 4. What effect does changing the concentration of sucrose have on the rate of osmosis? Explain. 5. Why does the rate of osmosis change over time? 6. Would the same results be obtained in exercise A if maltotriose (an impermeable trisaccharide, MW 504) was used in place of sucrose (an impermeable disaccharide, MW 342)? Explain. 1st 1 2 3 4 5 2nd 1 2 3 4 548-05-membrane_transport.doc 5.14 Bio 48 - Human Physiology Rev: 2/2/11 Exercise B – Simple Diffusion Averaged Data: Temperature Effects Cold (add the distances for all four cold tubes at 30 min etc. and divide by 4) Warm (add the distances for all four warm tubes at 30 min etc. and divide by 4) Averaged Total distance in mm at 30, 60 ,90...minutes 30 60 90 120 150 180 24 hours Cold Warm Averaged Data: Diffusion Medium (viscosity) Effects e.g. add the distances for all four 0.5% tubes or 2% at 30 min etc. and divide by 4) Averaged Total distance in mm at 30, 60 ,90...minutes 30 60 90 120 150 180 24 hours 0.5% 2% Averaged Data: Molecular Weight Effects e.g. add the distances for all four Eosin B or KmnO4 tubes at 30 min etc. and divide by 4) Averaged Total distance in mm at 30, 60 ,90...minutes 30 60 90 120 150 180 24 hours Eosin B KMnO4 30 min 60 min90 min 120 min 150 min 180 min 24 hrsTime48-05-membrane_transport.doc 5.15 Bio 48 - Human Physiology Rev: 2/2/11 1. What effect does an increase in molecular size have on the rate of diffusion? 2. What effect does temperature have on the rate of diffusion? 3. What effect does the diffusion medium (viscosity) have on the rate of diffusion? 4. What other factors (not evaluated here) influence the rate of diffusion? 5. Does the concentration of one molecule influence the rate of diffusion of another? Explain. 6. Does the rate of diffusion change over time? Explain. Exercise C – Differential Permeability Initial WeightWeight Change Weight (60 Min.) PART I PART IIPresence of StarchDialysis BagPresence of GlucoseTap Water(test-tube) 1. Did any diffusion, osmosis, or both occur? Explain. Support your conclusions with data obtained from this experiment. (Note: you will need to evaluate the data from both parts of this experiment to answer this question).48-05-membrane_transport.doc 5.16 Bio 48 - Human Physiology Rev: 2/2/11 2. Assume that instead of placing the dialysis bag in tap water that it was placed in a solution containing 1% starch (the dialysis bag still contains 5% glucose and 1% starch). What will happen to the following: a. Glucose molecules b. Starch molecules c. Water molecules d. Will the dialysis bag gain or lose weight? 3. Assume that instead of placing the dialysis bag in tap water that it was placed in a solution containing 5% glucose (the dialysis bag still contains 5% glucose and 1% starch). What will happen to the following: a. Glucose molecules b. Starch molecules c. Water molecules d. Will the dialysis bag gain or lose weight? Exercise D - Tonicity 1. Label each of the following solutions as either isotonic, hypotonic or hypertonic. 10% 0.45% 3.5% 0.20% 0.85% 0.00% 2. Define the following terms. Include a describe and explanation of what will happen to a red blood cell placed in each of these solutions: a) Isotonic b) Hypotonic c) Hypertonic. 3. Red blood cells will ___________ in a hypertonic solution. 4. A 0.10 M NaCl solution is _________tonic to a 0.10 M glucose solution.48-05-membrane_transport.doc 5.17 Bio 48 - Human Physiology Rev: 2/2/11 QUESTIONS 1. Suppose a salt and a glucose solution are separated by a membrane that is permeable to water but not to the solutes. The NaCl solution has a concentration of 1.95 g per 250 ml (molecular weight = 58.5). The glucose solution has a concentration of 9.0 g per 250 ml (molecular weight = 180). Calculate the molarity, millimolarity, and milliosmolarity of both solutions. State whether or not osmosis will occur and, if it will, in which direction. Explain your answer. 2. When the body needs to conserve water, the kidneys excrete a hypertonic urine. What do the terms isotonic and hypertonic mean? Since the fluid that is to become urine begins as an isotonic solution, what must happen to change it to a hypertonic urine? 3. The receptors for thirst are located in a part of the brain called the hypothalamus. These receptors are osmoreceptors—they are stimulated by an increase in blood osmolality. How would dehydration lead to a sense of thirst? What effect would drinking seawater have on his sense of thirst? Explain. 4. Before the invention of refrigerators, pioneers preserved meat by salting it. Explain how meat can be preserved by this procedure. (Hint: Think about what salting the meat would do to decomposer organisms, such as bacteria and fungi.)48-05-membrane_transport.doc 5.18 Bio 48 - Human Physiology Rev: 2/2/11 Review Calculations - Solution Concentrations 1.) Define molecular weight and gram molecular weight. 2.) Define Mole. 3.) Define Molarity. 4.) Define solvent, solute and solution. 5.) How much solute is in: a) 1 liter of a 1 Molar solution? b) 500 ml of a 1 Molar solution? c) 500 ml of a 2 Molar solution? 6.) Determine the