Chapter 7 Test - AP Biology

40 Questions | Total Attempts: 1274

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AP Biology Quizzes & Trivia

Questions and Answers
  • 1. 
    Which of the following types of molecules are the major structural components of the cell membrane?
    • A. 

      Phospholipids and cellulose

    • B. 

      Nucleic acids and proteins

    • C. 

      Phospholipids and proteins

    • D. 

      Proteins and cellulose

    • E. 

      Glycoproteins and cholesterol

  • 2. 
    When biological membranes are frozen and then fractured, they tend to break along the middle of the bilayer.  The best explanation for this is that
    • A. 

      The integral membrane proteins are not strong enough to hold the bilayer together.

    • B. 

      Water that is present in the middle of the bilayer freezes and is easily fractured.

    • C. 

      Hydrophilic interactions between the opposite membrane surfaces are destroyed on freezing.

    • D. 

      The carbon-carbon bonds of the phospholipid tails are easily broken.

    • E. 

      The hydrophobic interactions that hold the membrane together are weakest at this point.

  • 3. 
    All of the following molecules are part of the cell membrane except
    • A. 

      Lipids.

    • B. 

      Nucleic acids.

    • C. 

      Proteins.

    • D. 

      Phosphate groups.

    • E. 

      Steroids.

  • 4. 
    The original model for the bilayer structure of cell membranes, which was prepared in the 1920s, was based on which of the following?
    • A. 

      Detailed electron micrographs of freeze-fractured membranes

    • B. 

      The presence of proteins as a functional component of biological membranes

    • C. 

      The observation that all membranes contain phospholipids and proteins

    • D. 

      The understanding that phospholipids are amphipathic molecules

  • 5. 
    The presence of cholesterol in the plasma membranes of some animals
    • A. 

      Enables the membrane to stay fluid more easily when cell temperature drops.

    • B. 

      Enables the animal to remove hydrogen atoms from saturated phospholipids.

    • C. 

      Enables the animal to add hydrogen atoms to unsaturated phospholipids.

    • D. 

      Makes the membrane less flexible, allowing it to sustain greater pressure from within the cell.

    • E. 

      Makes the animal more susceptible to circulatory disorders.

  • 6. 
    According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?
    • A. 

      They can move laterally along the plane of the membrane.

    • B. 

      They frequently flip-flop from one side of the membrane to the other.

    • C. 

      They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane.

    • D. 

      They are free to depart from the membrane and dissolve in the surrounding solution.

    • E. 

      They have hydrophilic tails in the interior of the membrane.

  • 7. 
    The lateral mobility (fluidity) of lipids and proteins in membranes is a consequence of
    • A. 

      Lack of covalent bonds between the lipid and protein components of the membrane.

    • B. 

      Weak hydrophobic interactions among the components in the interior of the membrane.

    • C. 

      The presence of liquid water in the interior of the membrane.

    • D. 

      Lack of covalent bonds between the lipids and proteins and weak hydrophobic interactions among the components in the interior of the membrane and

    • E. 

      Lack of covalent bonds between lipids and proteins, weak hydrophobic interactions in the interior of the membrane, and the presence of liquid water in the interior of the membrane.

  • 8. 
    What is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold?
    • A. 

      By increasing the percentage of unsaturated phospholipids in the membrane

    • B. 

      By increasing the percentage of cholesterol molecules in the membrane

    • C. 

      By decreasing the number of hydrophobic proteins in the membrane

    • D. 

      By increasing the percentage of unsaturated phospholipids and increasing the percentage of cholesterol molecules in the membrane

    • E. 

      By increasing the percentage of unsaturated phospholipids, increasing the percentage of cholesterol molecules, and decreasing the number of hydrophobic proteins in the membrane

  • 9. 
    The surface of an integral membrane protein would be best described as
    • A. 

      Hydrophilic.

    • B. 

      Hydrophobic.

    • C. 

      Amphipathic.

    • D. 

      Completely covered with phospholipids.

    • E. 

      Exposed on only one surface of the membrane.

  • 10. 
    When a membrane is freeze-fractured, the bilayer splits down the middle between the two layers of phospholipids.  In an electron micrograph of a freeze-fractured membrane, the bumps seen on the fractured surface of the membrane are
    • A. 

      Peripheral proteins.

    • B. 

      Phospholipids.

    • C. 

      Carbohydrates.

    • D. 

      Integral proteins.

    • E. 

      Cholesterol molecules.

  • 11. 
    All of the following are functions of integral membrane proteins except
    • A. 

      Protein synthesis.

    • B. 

      Active transport.

    • C. 

      Hormone reception.

    • D. 

      Cell adhesion.

    • E. 

      Cytoskeleton attachment.

  • 12. 
    Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperatures?
    • A. 

      The double bonds form a kink in the fatty acid tail, forcing adjacent lipids to be further apart.

    • B. 

      Unsaturated fatty acids have a higher cholesterol content.

    • C. 

      Unsaturated fatty acids permit more water in the interior of the membrane.

    • D. 

      The double bonds block interaction among the hydrophilic head groups of the lipids.

    • E. 

      The double bonds result in a shorter fatty acid tail.

  • 13. 
    Which of the following is correct about integral membrane proteins?
    • A. 

      They lack tertiary structure.

    • B. 

      They are loosely bound to the surface of the bilayer.

    • C. 

      They are usually transmembrane proteins.

    • D. 

      They are not mobile within the bilayer.

    • E. 

      They serve only a structural role in membranes.

  • 14. 
    Of the following functions, which is most important for the glycoproteins and glycolipids of animal cell membranes?
    • A. 

      Facilitated diffusion of molecules down their concentration gradients

    • B. 

      Active transport of molecules against their concentration gradients

    • C. 

      Maintaining the integrity of a fluid mosaic membrane

    • D. 

      Maintaining membrane fluidity at low temperatures

    • E. 

      A cell's ability to distinguish one type of neighboring cell from another

  • 15. 
    What is one of the functions of cholesterol in animal cell membranes?
    • A. 

      Facilitates transport of ions

    • B. 

      Stores energy

    • C. 

      Maintains membrane fluidity

    • D. 

      Speeds diffusion

    • E. 

      Phosphorylates ADP

  • 16. 
    What membrane-surface molecules are thought to be most important as cells recognize each other?
    • A. 

      Phospholipids

    • B. 

      Integral proteins

    • C. 

      Peripheral proteins

    • D. 

      Cholesterol

    • E. 

      Glycoproteins

  • 17. 
    An animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function?
    • A. 

      Transporting ions against an electrochemical gradient

    • B. 

      Cell-cell recognition

    • C. 

      Maintaining fluidity of the phospholipid bilayer

    • D. 

      Attaching to the cytoskeleton

    • E. 

      Establishing the diffusion barrier to charged molecules

  • 18. 
    Which of the following adheres to the extracellular surface of animal cell plasma membranes?
    • A. 

      Fibers of the extracellular matrix

    • B. 

      Fibers of the cytoskeleton

    • C. 

      The phospholipid bilayer

    • D. 

      Cholesterol

    • E. 

      Carrier proteins

  • 19. 
    What kinds of molecules pass through a cell membrane most easily?
    • A. 

      Large and hydrophobic

    • B. 

      Small and hydrophobic

    • C. 

      Large polar

    • D. 

      Ionic

    • E. 

      Monosaccharides such as glucose

  • 20. 
    Which of the following is a characteristic feature of a carrier protein in a plasma membrane?
    • A. 

      It is a peripheral membrane protein.

    • B. 

      It exhibits a specificity for a particular type of molecule.

    • C. 

      It requires the expenditure of cellular energy to function.

    • D. 

      It works against diffusion.

    • E. 

      It has few, if any, hydrophobic amino acids.

  • 21. 
    After a membrane freezes and then thaws, it often becomes leaky to solutes.  The most reasonable explanation for this is that
    • A. 

      Transport proteins become nonfunctional during freezing.

    • B. 

      The lipid bilayer loses its fluidity when it freezes.

    • C. 

      Aquaporins can no longer function after freezing.

    • D. 

      The integrity of the lipid bilayer is broken when the membrane freezes.

    • E. 

      The solubility of most solutes in the cytoplasm decreases on freezing.

  • 22. 
    Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
    • A. 

      CO2

    • B. 

      An amino acid

    • C. 

      Glucose

    • D. 

      K+

    • E. 

      Starch

  • 23. 
    The selective permeability of biological membranes is dependent on which of the following?
    • A. 

      The type of transport proteins that are present in the membrane

    • B. 

      The lipid bilayer being permeable to primarily small, nonpolar molecules

    • C. 

      The types of carbohydrates on the surface of the membrane

    • D. 

      The type of transport proteins that are present in the membrane and the lipid bilayer being permeable to primarily small, nonpolar molecules

    • E. 

      The type of transport proteins that are present in the membrane, the lipid bilayer being permeable to primarily small, nonpolar molecules, and the types of carbohydrates on the surface of the membrane

  • 24. 
    Which of the following statements is correct about diffusion?
    • A. 

      It is very rapid over long distances.

    • B. 

      It requires an expenditure of energy by the cell.

    • C. 

      It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

    • D. 

      It is an active process in which molecules move from a region of lower concentration to one of higher concentration.

    • E. 

      It requires integral proteins in the cell membrane.

  • 25. 
    Water passes quickly through cell membranes because
    • A. 

      The bilayer is hydrophilic.

    • B. 

      It moves through hydrophobic channels.

    • C. 

      Water movement is tied to ATP hydrolysis.

    • D. 

      It is a small, polar, charged molecule.

    • E. 

      It moves through aquaporins in the membrane.

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