Cellular movement active transport synthesis of

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Cellular movement Active transport Synthesis of molecules Chemiosmosis Fermentation 2002: The following experiment was designed to test whether different concentration gradients affect the rate of diffusion. In this experiment, four solutions (0% NaCl, 1% NaCl, 5% NaCl, and 10% NaCl) were tested under identical conditions. Fifteen milliliters (mL) of 0% NaCl were put into a bag formed of dialysis tubing that is permeable to Na+, Cl- and water. The same was done for each NaCl solution. Each bag was submerged in a separate beaker containing 300mL of distilled water. The concentration of NaCl in mg/L in the water outside each bag was measured at 40-second intervals. The results from the 5% bag are shown in the table below. Time (seconds) NaCl (mg/L) 0 0 40 130 80 220 120 320 160 400 (a) On the axes provided, graph the data for the 5% NaCl solution. (b) Using the same set of axes, draw and label three additional lines representing the results that you would predict for the 0%, 1% and 10% NaCl solutions. Explain your predictions. (c) Farmlands located near costal regions are being threatened by encroaching seawater seeping into the soil. In terms of water movement into or out of plant cells, explain why seawater could decrease crop production. Include a discussion of water potential in your discussion. 2005: Water potential in potato cells was determined in the following manner. The initial masses of six groups of potato cores were measured. The potato cores were placed in sucrose solutions of various molarities. The masses of the cores were measured again after 24 hours. Percent changes in mass were calculated. The results are shown below. Molarity of Sucrose in Beaker Percent Change in Mass 0.0 M 18.0 0.2 5.0 0.4 -8.0 0.6 -16.0 0.8 -23.5 1.0 -24.0 (a) Graph these data on the axes provided. From your graph, find the apparent molar concentration (osmolarity) of the potato core cells. (b) What are the components of water potential, and why is water potential important for the movement of water in plants? (c) Predict what would happen to typical animal cells placed in 0.0 M and 1.0 M sucrose solutions, and explain your prediction. 2005: Yeast cells are placed in an apparatus with a solution of sugar (a major nutrient for yeast metabolism). The apparatus detects bubbles of gas released by the yeast cells. The rate of respiration varies with the surrounding temperatures as indicated by the data below. Temperature ( ˚ C) 0 10 20 30 40 50 60 70 Number of bubbles of gas produced per minute 0 3 7 12 7 4 1 0 a) Graph the results on the axes provided. Determine optimum temperature for respiration in the yeast. b) Respiration is a series of enzyme-catalyzed reactions. Using your knowledge of enzymes and the data above, analyze and explain the results of this experiment. c) Design an experiment to test the effect of varying the pH of the sugar solution on the rate of respiration. Include a prediction of the expected results.
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