Cell Structure, Diffusion, Osmosis, and Active Transport Practice Problems


Questions 1 - 2 refer to the following situation:



6% sugar                      2% sugar




  Cell A                         Cell B


Assume that the two cells above have no other dissolved materials in them and that the membrane between the cells is permeable to water, but impermeable to sugar.


1.        In which direction will water movement occur between the two cells?  Why? 


2.        What will happen to the percent of sugar in cell B?  Why? 


        3.     Assume the two cells below are permeable to both chloride and calcium ions. Explain the results seen in the cells below in terms of diffusion and/or active transport.

     4.    About twelve to twenty four hours after the last meal, a person's blood sugar level normally varies from 60 to 90 milligrams (mg) per 100 milliliters (ml) of blood, though it may rise to 130mg/100ml after meals high in carbohydrates.  That the blood sugar   level is maintained within a fairly narrow range despite uneven intake of sugar is due to the body’s ability to carry out _______________________?  Suppose that blood sugar levels do not remain constant, what impact would elevated blood sugar have on the body’s cells, e.g. red blood cells?  Explain your prediction in terms of osmosis.


     5.    A freshwater Protozoa called a Paramecium expels excess water from its body by a cell structure called the contractile vacuole.  If this paramecium floated down a river into a salt-water estuary predict what would happen to the level of activity of its contractile vacuole.  Explain your prediction in terms of osmosis.


For questions 6 - 8 use the following key to answer the question posed.


           KEY:          A. HYPERTONIC

                                B. ISOTONIC

                                C. HYPOTONIC


    6.     If the internal salt concentration of Horatio is 3.6% and you place it in a solution of 3.6%, what would you call this solution?


     7.    You placed marine Critter X in a solution with an unknown solute concentration.  In two hours you examine Critter X and notice that all its cells are swelling and bursting.  The water concentration of Critter X must have been   ?     in order for these results to occur.


     8.    Red blood cells  are ____?___ to their environment.



     9.    What would happen to the cells of a sea star if you placed it in a hypotonic medium? Explain why. 


10.   What would happen to the cells of a plant if you placed it in a hypotonic medium? Explain why.


Multiple Guess Questions


11.    Which process would include a net movement of sugar molecules through a membrane from a region of lower concentration to a region of higher concentration?     (a) osmosis     (b) diffusion     (c) active transport     (d) passive transport   (e)  facilitated diffusion

12.     In the human body, the potassium ion can pass easily through cell membranes, yet the potassium ion concentration is higher inside many cells than it is        outside these cells. This condition is mainly a result of the process of

        (a) passive transport     (b) active transport     (c) osmosis     (d) phagocytosis    (e)  facilitated diffusion

13. Chemical analysis indicates that the cell membrane is composed mainly of

         (a) proteins and starch     (b) proteins and cellulose     (c) lipids and starch     (d) lipids and  proteins

14. The net flow of materials through the membrane of a cell against a concentration gradient is known as

            (a) passive transport         (b) active transport         (c) osmosis         (d) pinocytosis
15. When a cell uses energy to move materials across a cell membrane, the process is known as

           (a) osmosis     (b) active transport     (c) diffusion     (d) passive transport    (e)  facilitated diffusion

16. The diffusion of water molecules into and out of cells is called   

            (a) diffusion     (b) pinocytosis     (c) osmosis     (d) active transport    (e)  facilitated diffusion

17. The net movement of molecules into cells is most dependent upon the
        (a) selectivity of the plasma membrane
         b) selectivity of the cell wall
        (c) number of nucleoli
        (d) the genetic make up of the cell

18. A red blood cell placed in distilled water will swell and burst due to the diffusion of
        (a) salt from the red blood cell into the water
        (b) water into the red blood cell
        (c) water from the blood cell into its environment
        (d) salts from the water into the red blood cell

        (e)  facilitated diffusion

Match the followings
  1. Lysosomes 
  2. Golgi complex 
  3. Smooth ER
  4. Nucleolus 
  5. Rough ER 
  6. Cytoskeleton 
  7. Cilia 
  8. Vesicles
  9. ribosomes (cytoplasmic)
  1. Maintenance of cellular shape
  2. Long, whip-like structure for cellular movement
  3. Processing and chemical modification center of the cell
  4. Digestion
  5. Production of ribosomes
  6. Maintenance of the water balance within a cell
  7. Synthesis of proteins exported from the cell and proteins used in other organelles
  8. Short, hair-like structure for cellular movement.
  9. Lipid biosynthesis
  10. Storage and transport of substances within a cell
  11. Synthesis of proteins found in the cytoplasm

Refer to the figure, below, to answer the following two questions. The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 molar glucose and 0.5 molar sodium chloride (NaCl) and side B is filled with a solution containing 0.8 molar glucose and 0.4 molar sodium chloride. Initially, the volume in both arms is the same.

28.  At the beginning of the experiment,

     a.) side A is hypertonic to side B.

     b.) side A is hypotonic to side B.

     c.) side A is isotonic to side B.

     d.) side A is hypertonic to side B with respect to glucose.

     e.) side A is hypotonic to side B with respect to NaCl.


29.  If you examine side A after 3 days, you should find

       a.) a decrease in the concentration of NaCl and glucose and an increase in the water level.

       b.) a decrease in the concentration of NaCl, an increase in water level, and no change in the    concentration of glucose.

       c.) no net change in the system.

       d.) a decrease in the concentration of NaCl and a decrease in the water level.

       e.) no change in the concentration of NaCl and glucose and an increase in the water level.