1. Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. As a result, these lipid rafts
    A) are more fluid than the surrounding membrane.
    B) are more rigid than the surrounding membrane.
    C) are able to flip from inside to outside.
    D) detach from the plasma membrane and clog arteries.
    E) have higher rates of lateral diffusion of lipids and proteins into and out of the lipid rafts.
  2. 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
  3. Singer and Nicolson's fluid mosaic model of the membrane proposed that
    A) membranes are a phospholipid bilayer.
    B) membranes are a phospholipid bilayer between two layers of hydrophilic proteins.
    C) membranes are a single layer of phospholipids and proteins.
    D) membranes consist of protein molecules embedded in a fluid bilayer of phospholipids.
    E) membranes consist of a mosaic of polysaccharides and proteins.
  4. 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.
  5. In order for a protein to be an integral membrane protein it would have to be
    A) hydrophilic.
    B) hydrophobic.
    C) amphipathic, with at least one hydrophobic region.
    D) completely covered with phospholipids.
    E) exposed on only one surface of the membrane.
  6. 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 kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
    B) Unsaturated fatty acids have a higher cholesterol content and therefore more cholesterol in membranes.
    C) Unsaturated fatty acids are more polar than saturated fatty acids.
    D) The double bonds block interaction among the hydrophilic head groups of the lipids.
    E) The double bonds result in shorter fatty acid tails and thinner membranes.
  7. Which of the following is true of 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.
  8. Which of these are not embedded in the hydrophobic portion of the lipid bilayer at all?
    A) transmembrane proteins
    B) integral proteins
    C) peripheral proteins
    D) integrins
    E) glycoproteins
  9. 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
  10. 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.
  11. Nitrous oxide gas molecules passing across a cell's plasma membrane without help from another protein and moving from high concentration to low concentration is an example of
    A) diffusion across the lipid bilayer.
    B) facilitated diffusion.
    C) active transport.
    D) osmosis.
    E) cotransport.
  12. 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
  13. 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.
  14. Celery stalks that are immersed in fresh water for several hours become stiff and hard. Similar stalks left in a 0.15 M salt solution become limp and soft. From this we can deduce that the cells of the celery stalks are
    A) hypotonic to both fresh water and the salt solution.
    B) hypertonic to both fresh water and the salt solution.
    C) hypertonic to fresh water but hypotonic to the salt solution.
    D) hypotonic to fresh water but hypertonic to the salt solution.
    E) isotonic with fresh water but hypotonic to the salt solution.
  15. Mammalian blood contains the equivalent of 0.15 M NaCl. Seawater contains the equivalent of 0.45 M NaCl. What will happen if red blood cells are transferred to seawater?
    A) Water will leave the cells, causing them to shrivel and collapse.
    B) NaCl will be exported from the red blood cells by facilitated diffusion.
    C) The blood cells will take up water, swell, and eventually burst.
    D) NaCl will passively diffuse into the red blood cells.
    E) The blood cells will expend ATP for active transport of NaCl into the cytoplasm.
  16. Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells?
    A) The animal cell is in a hypotonic solution, and the plant cell is in an isotonic solution.
    B) The animal cell is in an isotonic solution, and the plant cell is in a hypertonic solution.
    C) The animal cell is in a hypertonic solution, and the plant cell is in an isotonic solution.
    D) The animal cell is in an isotonic solution, and the plant cell is in a hypotonic solution.
    E) The animal cell is in a hypertonic solution, and the plant cell is in a hypotonic solution.
  17. When a plant cell, such as one from a peony stem, is submerged in a very hypotonic solution, what is likely to occur?
    A) The cell will burst.
    B) The cell membrane will lyse.
    C) Plasmolysis will shrink the interior.
    D) The cell will become flaccid.
    E) The cell will become turgid.
  18. The phosphate transport system in bacteria imports phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Phosphate import depends on a pH gradient across the membrane–more acidic outside the cell than inside the cell. Phosphate transport is an example of
    A) passive diffusion.
    B) facilitated diffusion.
    C) active transport.
    D) osmosis.
    E) cotransport.
  19. Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Using this information, which transport mechanism is most probably functioning in the intestinal cells?
    A) simple diffusion
    B) phagocytosis
    C) active transport pumps
    D) exocytosis
    E) facilitated diffusion
  20. An organism with a cell wall would most likely be unable to take in materials through
    A) diffusion.
    B) osmosis.
    C) active transport.
    D) phagocytosis.
    E) facilitated diffusion.
  21. A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in
    A) peroxisomes.
    B) lysosomes.
    C) Golgi vesicles.
    D) vacuoles.
    E) secretory vesicles.
  22. According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly
    A) spread in a continuous layer over the inner and outer surfaces of the membrane.
    B) confined to the hydrophobic interior of the membrane.
    C) embedded in a lipid bilayer.
    D) randomly oriented in the membrane, with no fixed inside-outside polarity.
    E) free to depart from the fluid membrane and dissolve in the surrounding solution.
  23. Which of the following factors would tend to increase membrane fluidity?
    A) a greater proportion of unsaturated phospholipids
    B) a greater proportion of saturated phospholipids
    C) a lower temperature
    D) a relatively high protein content in the membrane
    E) a greater proportion of relatively large glycolipids compared with lipids having smaller molecular masses
  24. When biologists wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using
    A) a phase-contrast light microscope.
    B) a scanning electron microscope.
    C) a transmission electronic microscope.
    D) a confocal fluorescence microscope.
    E) a super-resolution fluorescence microscope.
  25. The advantage of light microscopy over electron microscopy is that
    A) light microscopy provides for higher magnification than electron microscopy.
    B) light microscopy provides for higher resolving power than electron microscopy.
    C) light microscopy allows one to view dynamic processes in living cells.
    D) light microscopy provides higher contrast than electron microscopy.
    E) specimen preparation for light microcopy does not produce artifacts.
  26. All of the following are part of a prokaryotic cell except
    A) DNA.
    B) a cell wall.
    C) a plasma membrane.
    D) ribosomes.
    E) an endoplasmic reticulum.
  27. The volume enclosed by the plasma membrane of plant cells is often much larger than the corresponding volume in animal cells. The most reasonable explanation for this observation is that
    A) plant cells are capable of having a much higher surface-to-volume ratio than animal cells.
    B) plant cells have a much more highly convoluted (folded) plasma membrane than animal cells.
    C) plant cells contain a large vacuole that reduces the volume of the cytoplasm.
    D) animal cells are more spherical, whereas plant cells are elongated.
    E) plant cells can have lower surface-to-volume ratios than animal cells because plant cells synthesize their own nutrients.
  28. The evolution of eukaryotic cells most likely involved
    A) endosymbiosis of an aerobic bacterium in a larger host cell–the endosymbiont evolved into mitochondria.
    B) anaerobicarchaea taking up residence inside a larger bacterial host cell to escape toxic oxygen–the anaerobic bacterium evolved into chloroplasts.
    C) anendosymbiotic fungal cell evolved into the nucleus.
    D) acquisition of an endomembrane system, and subsequent evolution of mitochondria from a portion of the Golgi.
  29. Which organelle or structure is absent in plant cells?
    A) mitochondria
    B) Golgi vesicles
    C) microtubules
    D) centrosomes
    E) peroxisomes
  30. Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
    A) lipids
    B) glycogen
    C) proteins
    D) cellulose
    E) nucleic acids
  31. Which type of organelle or structure is primarily involved in the synthesis of oils, phospholipids, and steroids?
    A) ribosome
    B) lysosome
    C) smooth endoplasmic reticulum
    D) mitochondrion
    E) contractile vacuole
  32. Which structure is the site of the synthesis of proteins that may be exported from the cell?
    A) rough ER
    B) lysosomes
    C) plasmodesmata
    D) Golgi vesicles
    E) free cytoplasmic ribosomes
  33. The Golgi apparatus has a polarity or sidedness to its structure and function. Which of the following statements correctly describes this polarity?
    A) Transport vesicles fuse with one side of the Golgi and leave from the opposite side.
    B) Proteins in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other.
    C) Lipids in the membrane of the Golgi may be sorted and modified as they move from one side of the Golgi to the other.
    D) Soluble proteins in the cisternae (interior) of the Golgi may be sorted and modified as they move from one side of the Golgi to the other.
    E) All of the above correctly describe polar characteristics of the Golgi function.
  34. Hydrolytic enzymes must be segregated and packaged to prevent general destruction of cellular components. Which of the following organelles contains these hydrolytic enzymes in animal cells?
    A) chloroplast
    B) lysosome
    C) central vacuole
    D) peroxisome
    E) glyoxysome
  35. The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and therefore abundant in liver cells?
    A) rough ER
    B) smooth ER
    C) Golgi apparatus
    D) nuclear envelope
    E) transport vesicles
  36. Which of the following produces and modifies polysaccharides that will be secreted?
    A) lysosome
    B) vacuole
    C) mitochondrion
    D) Golgi apparatus
    E) peroxisome
  37. Which organelle often takes up much of the volume of a plant cell?
    A) lysosome
    B) vacuole
    C) mitochondrion
    D) Golgi apparatus
    E) peroxisome
  38. Which organelle is the primary site of ATP synthesis in eukaryotic cells?
    A) lysosome
    B) vacuole
    C) mitochondrion
    D) Golgi apparatus
    E) peroxisome
  39. Which plant cell organelle contains its own DNA and ribosomes?
    A) glyoxysome
    B) vacuole
    C) mitochondrion
    D) Golgi apparatus
    E) peroxisome
  40. Thylakoids, DNA, and ribosomes are all components found in
    A) vacuoles.
    B) chloroplasts.
    C) mitochondria.
    D) lysosomes.
    E) nuclei.
  41. In a plant cell, DNA may be found
    A) only in the nucleus.
    B) only in the nucleus and mitochondria.
    C) only in the nucleus and chloroplasts.
    D) in the nucleus, mitochondria, and chloroplasts.
    E) in the nucleus, mitochondria, chloroplasts, and peroxisomes.
  42. Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures?
    A) sites of energy production in cellular respiration
    B) membrane proteins
    C) ribosomes
    D) cytoskeletal structures
    E) cellulose fibers in the cell wall
  43. Movement of vesicles within the cell depends on what cellular structures?
    A) microtubules and motor proteins
    B) actin filaments and microtubules
    C) actin filaments and ribosomes
    D) centrioles and motor proteins
    E) actin filaments and motor proteins
  44. Which of the following contain the 9 + 2 arrangement of microtubules, consisting of nine doublets of microtubules surrounding a pair of single microtubules?
    A) both motile cilia and primary (nonmotile) cilia
    B) centrioles only
    C) both flagella and motile cilia
    D) both basal bodies and primary (nonmotile) cilia
    E) both centrioles and basal bodies
  45. What do the cell walls of plants and the extracellular matrix of animal cells have in common?
    A) They are largely composed of phospholipids and glycoproteins.
    B) Their proteins are made by free cytoplasmic ribosomes.
    C) They form rigid structures that provide structural support for cells but limit their expansion.
    D) They limit the passage of small molecules.
    E) They have functional connections with the cytoskeleton inside the cell.
  46. Which of the following is present in a prokaryotic cell?
    A) mitochondrion
    B) ribosome
    C) nuclear envelope
    D) chloroplast
    E) ER
  47. Which structure-function pair is mismatched?
    A) nucleolus; production of ribosomal subunits
    B) lysosome; intracellular digestion
    C) ribosome; protein synthesis
    D) Golgi; protein trafficking
    E) microtubule; muscle contraction
  48. Which of the following is (are) true for anabolic pathways?
    A) They do not depend on enzymes.
    B) They are usually highly spontaneous chemical reactions.
    C) They consume energy to build up polymers from monomers.
    D) They release energy as they degrade polymers to monomers.
    E) They consume energy to decrease the entropy of the organism and its environment.
  49. Which of the following is a statement of the first law of thermodynamics?
    A) Energy cannot be created or destroyed.
    B) The entropy of the universe is decreasing.
    C) The entropy of the universe is constant.
    D) Kinetic energy is stored energy that results from the specific arrangement of matter.
    E) Energy cannot be transferred or transformed.
  50. Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?
    A) Living organisms do not obey the second law of thermodynamics, which states that entropy must increase with time.
    B) Life obeys the second law of thermodynamics because the decrease in entropy as the organism grows is exactly balanced by an increase in the entropy of the universe.
    C) Living organisms do not follow the laws of thermodynamics.
    D) As a consequence of growing, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their growth.
    E) Living organisms are able to transform energy into entropy.
  51. Whenever energy is transformed, there is always an increase in the
    A) free energy of the system.
    B) free energy of the universe.
    C) entropy of the system.
    D) entropy of the universe.
    E) enthalpy of the universe.
  52. In alcohol fermentation, NAD⁺ is regenerated from NADH by
    A) reduction of acetaldehyde to ethanol (ethyl alcohol).
    B) oxidation of pyruvate to acetyl CoA.
    C) reduction of pyruvate to form lactate.
    D) oxidation of ethanol to acetyl CoA.
    E) reduction of ethanol to pyruvate.
  53. Which of the following is an example of potential rather than kinetic energy?
    A) the muscle contractions of a person mowing grass
    B) water rushing over Niagara Falls
    C) light flashes emitted by a firefly
    D) a molecule of glucose
    E) the flight of an insect foraging for food
  54. Which of the following is true of metabolism in its entirety in all organisms?
    A) Metabolism depends on a constant supply of energy from food.
    B) Metabolism depends on an organism's adequate hydration.
    C) Metabolism uses all of an organism's resources.
    D) Metabolism consists of all the energy transformation reactions in an organism.
    E) Metabolism manages the increase of entropy in an organism.
  55. The mathematical expression for the change in free energy of a system is ΔG =ΔH - TΔS. Which of the following is (are) correct?
    A) ΔS is the change in enthalpy, a measure of randomness.
    B) ΔH is the change in entropy, the energy available to do work.
    C) ΔG is the change in free energy.
    D) T is the temperature in degrees Celsius.
  56. Which of the following is true for all exergonic reactions?
    A) The products have more total energy than the reactants.
    B) The reaction proceeds with a net release of free energy.
    C) The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants.
    D) A net input of energy from the surroundings is required for the reactions to proceed.
    E) The reactions are rapid.
  57. A chemical reaction that has a positive ΔG is correctly described as
    A) endergonic.
    B) endothermic.
    C) enthalpic.
    D) spontaneous.
    E) exothermic.
  58. Which of the following best describes enthalpy (H)?
    A) the total kinetic energy of a system
    B) the heat content of a chemical system
    C) the system's entropy
    D) the cell's energy equilibrium
    E) the condition of a cell that is not able to react
  59. Why is ATP an important molecule in metabolism?
    A) Its hydrolysis provides an input of free energy for exergonic reactions.
    B) It provides energy coupling between exergonic and endergonic reactions.
    C) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy.
    D) Its terminal phosphate bond has higher energy than the other two.
    E) It is one of the four building blocks for DNA synthesis.
  60. Which of the following statements is true concerning catabolic pathways?
    A) They combine molecules into more energy-rich molecules.
    B) They supply energy, primarily in the form of ATP, for the cell's work.