Life on Earth
Chapter 6
Cell Membrane Structure and Function
[logo]
Self-Quiz

  1. Active transport through the plasma membrane occurs through the action of
    1. diffusion
    2. membrane proteins
    3. DNA
    4. water
    5. osmosis

  2. The following is a characteristic of a cell membrane:
    1. It separates the cell contents from its environment.
    2. It is permeable to certain substances.
    3. It is a lipid bilayer with embedded proteins.
    4. It contains sodium-potassium pumps.
    5. all of the above

  3. If an animal cell is placed into a solution whose concentration of solutes is higher than that inside the cell
    1. The cell will swell.
    2. The cell will shrivel.
    3. The cell will remain the same size.
    4. The solution is described as hypertonic.
    5. Both b and d are correct.

  4. Small, nonpolar hydrophobic molecules such as fatty acids
    1. pass readily through a membrane's lipid bilayer
    2. diffuse very slowly through the lipid bilayer
    3. require special channels to enter a cell
    4. are actively transported across cell membranes
    5. must enter the cell via endocytosis

  5. Which of the following would be least likely to diffuse through a lipid bilayer?
    1. water
    2. oxygen
    3. carbon dioxide
    4. sodium ions
    5. the small, nonpolar molecule butane

  6. Which of the following are evidence that a substance enters a cell by active transport rather than diffusion?
    1. A carrier protein moves the substance across the membrane.
    2. The substance enters the cell when its concentration is higher outside than inside.
    3. The breakdown of ATP is required for the substance to move into the cell.
    4. The substance moves through a channel protein.
    5. all of the above

  7. All of the following are false about cell walls, except:
    1. Cell walls are nonliving.
    2. Cell walls are secreted by the cells they surround.
    3. Bacteria, fungi, and some Protista possess cell walls.
    4. a and c are correct.
    5. All of these are true.

  8. The primary component of cell walls of plants is:
    1. chitin
    2. cellulose
    3. pectin
    4. lignin
    5. protein

  9. All the following are true of the plasma membrane except:
    1. The plasma membrane forms a boundary between the cytoplasm and the external environment.
    2. Cells are capable of communication because of the nature of the plasma membrane.
    3. Regulation of materials moving into an out cell is accomplished by the plasma membrane.
    4. The plasma membrane receives signals from other cells.
    5. The outermost structure of all eukaryotic cells is the plasma membrane.

  10. Why do the tails of phospholipids point toward each other and the heads of the phospholipids point out?
    1. The tails are nonpolar and form hydrogen bonds with each other.
    2. The tails are repelled by the aqueous environment.
    3. The heads are attracted to the water inside and outside.
    4. a and c
    5. b and c

  11. What is the role of the transport and channel proteins within the fluid mosaic of a plasma membrane?
    1. They prevent passage of amino acids.
    2. They allow movement of salts and sugars through the plasma membrane.
    3. They may set off cellular changes such as cell division or hormone secretion.
    4. They are cell-surface attachment sites.
    5. They identify the cell.

  12. In general, which of the following is largely responsible for moving substances across the plasma membrane, communicating with other cells, and identifying the cell?
    1. phospholipids
    2. carbohydrates
    3. proteins
    4. nucleic acids
    5. cytoskeleton

  13. In a cell, "differentially permeable" means:
    1. It has different-sized perforations in the membrane.
    2. It is permeable to different substances than other cells.
    3. Only certain molecules can pass through.
    4. Sometimes water passes through, and sometimes it can not.
    5. Permeability depends on gradient differences.

  14. Molecules that can diffuse freely through a phospholipid bilayer are probably:
    1. hydrophilic
    2. positively charged
    3. hydrophobic
    4. negatively charged
    5. a sugar

  15. A certain cell, such as a neuron, has a high concentration of K+ ions. K+ ions continue to enter the cell via which cellular mechanism?
    1. active transport
    2. facilitated diffusion
    3. osmosis
    4. endocytosis
    5. infusion

  16. Your favorite house plant has wilted. To restore your plant, you add a solution that is ____________________to the soil.
    1. isotonic
    2. hypertonic
    3. hydrophilic
    4. hypothetical
    5. hypotonic

  17. Adhesion of animal tissues and cells is accomplished by cell-to-cell junctions called
    1. desmosomes
    2. tight junctions
    3. gap junctions
    4. plasmodesmata
    5. cell plates

      

PH Sower © 1997 by Prentice-Hall, Inc.
Simon & Schuster/A Viacom Company
Upper Saddle River, New Jersey 07458

Legal Statement