Biology stops

Name: Date: 10/14/2013 1. What types of molecules have difficulty crossing the plasma membrane? Explain why. Large polar molecules and ions cannot cross plasma membranes easily, because the inner hydrophobic section of the membrane impedes the movement of these molecules. 2. What does the term concentration gradient mean? Concentration that exists between two different areas 3. A solution of 1M glucose is separated by a selectively permeable membrane from a solution of 0.2M fructose and 0.7M sucrose. The membrane is not permeable to the sugar molecules. Indicate which side is initially hypertonic and which is hypotonic. Show, using an arrow, the direction of osmosis.

4. Red blood cells are placed in three beakers containing the following solutions: Beaker distilled water, Beaker B – isotonic solution, Beaker C – 5% salt solution. Describe the effect each solution will have on the cells and explain why. a. Cells in Beaker A: the cells will burst

b. Cells in Beaker B: They will stay the same.

c. Cells in Beaker C: The cell will shrink.
5. Explain why a turgid plant cell placed in a solution in an open beaker