Passive vs. Active Transport How Substances Move Across Cell Membranes

University:
Boston University
Course:
CAS BI 105 | Introductory Biology for Health Sciences
Academic year:

2020
Views:

165

Pages:

4
Author:

Carissa Thomas

1. Compare passive transport (simple diffusion, facilitated diffusion, osmosis) with active transport. Discuss concentration gradients and give examples. 2. What is the function of proteins that are embedded into the cell membrane of cells? Some can act as channel proteins, carrier proteins - for polar or charged molecules that cannot easily pass on their own. Glucose or ions need a protein to pass the phospholipid bilayer. 3. Explain what happens to red blood cells (normally contain .9% NaCl) when placed in the following solutions and provide an explanation for each: a) Hypotonic solution (100% distilled water): Water will diffuse into the cells. Water will move from a high to low concentration (to where there is more solute, less water). Cells will swell and burst. b) Isotonic solution (.9% NaCl): Water will diffuse in and out at an equal rate. Equal solute and water on each side. No net change in mass. Cells remain the same size. c) Hypertonic solution (90% water, 10% salt): Water will diffuse out of the cells; water moves from a high to low concentration (to where there is more solute, less water). Cells will shrink in size. 4. Use the following diagram to determine whether the concentration of the following molecules will remain the same, increase or decrease in the bag after 30 minutes. Amount of starch in the bag will _______remain the same______________________. Amount of glucose in the bag will _____decrease_______________________. Amount of iodine in the bag will _______increase_______________________. Amount of water in the bag will ________increase______________________. 5. A sweet potato was peeled and cut into 18 identical cubes. The initial mass was recorded. Three of each cube was soaked in a different sucrose solution overnight at a temperature of 25 degrees Celsius. The cubes were then removed and the final mass was recorded. The percent change in mass was calculated for each cube and the results are shown in the graph below. a) Calculate the water potential (in bars) of the sweet potato at 25 degrees Celsius. Give your answer to one decimal place. Water Potential: 6. For each of the following organic compounds, list the elements they contain and describe the function of that organic compound. Choose from the following list of elements: Elements= Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Sulfur Organic compounds:

Passive vs. Active Transport How Substances Move Across Cell Membranes

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