Chapter Chapter 5: The Working Cell
 
Chapter Quiz
 

1 .       What is energy? (5.1) [Hint]

 the capacity to perform work
 the amount of food eaten
 movement
 the rearrangement of chemical molecules within matter
 the capacity to produce heat
2 .       According to the second law of thermodynamics, which of the following is true? (5.2) [Hint]

 The total amount of energy in the universe is constant.
 Energy conversions increase the order in the universe.
 The ordering of one system depends on the disordering of another.
 The entropy of the universe is constantly decreasing.
 All reactions produce some heat.
3 .       Which one of the following is an example of the second law of thermodynamics? (5.2) [Hint]

 The aerobic respiration of glucose generates heat.
 All types of cellular respiration produce ATP.
 CO2 is exhaled as a by-product of aerobic respiration.
 Photosynthesis enables plants to create energy from sunlight.
 Energy is stored during the Calvin cycle.
4 .       If the entropy of a system is increasing, this means that ____________. (5.2) [Hint]

 the first law of thermodynamics is being violated
 the sun's energy is being captured by photosynthesis
 heat is being used by organisms as a source of energy
 energy input will be needed to maintain organization
 the amount of usable energy in the system is increasing
5 .       The first law of thermodynamics ____________. (5.2) [Hint]

 states that energy is neither created nor destroyed
 deals with entropy
 deals with heat content
 states that entropy spontaneously increases
 predicts the direction of a reaction
6 .       Which one of the following is NOT true about the second law of thermodynamics? (5.2) [Hint]

 It states that energy is neither created nor destroyed.
 It deals with entropy.
 It deals with heat content.
 It deals with spontaneity.
 All the above are true.
7 .       Cellular respiration is an example of _____. (5.3) [Hint]

 an endergonic reaction
 an exergonic reaction
 bioenergetics
 thermodynamics
 entropy
8 .       A reaction is designated as exergonic rather than endergonic when ___________. (5.3) [Hint]

 activation energy exceeds net energy release
 activation energy is necessary
 no kinetic energy is released
 the potential energy of the products is less than the potential energy of the reactants
 it absorbs more energy
9 .       Most cellular work is accomplished by _____ energizing molecules by _____ them. (5.4) [Hint]

 enzymes ... activating
 coenzyme ... activating
 substrates ... phosphorylating
 ATP ... phosphorylating
 cofactors ... activating
10 .       The mechanism of enzyme action is _____. (5.5) [Hint]

 to create an energy barrier between substrates
 to lower the energy of the activation of a reaction
 to change the direction of thermodynamic equilibrium
 to change endergonic into exergonic reactions
 to allow substrates to move more freely in solution
11 .       Three or four of the following statements concerning enzymes are true and correct. Which one, if any, is NOT correct? If all the statements are correct, choose "All of the above." (5.6) [Hint]

 Most enzymes are proteins.
 An enzyme is not consumed by the catalytic process.
 An enzyme is very specific in terms of which substrates it can bind to.
 An enzyme lowers the activation energy of a chemical reaction.
 All of the above.
12 .       If the tertiary structure of an enzyme is changed _____. (5.6) [Hint]

 its substrate may not fit properly in the active site
 it will be missing one of its polypeptides
 the helical coil will be stretched out
 the product of the reaction will be a different molecule
 its substrate will bond covalently with the wrong part of the molecule
13 .       Which of the following environments or actions does NOT affect enzyme activity? (5.7) [Hint]

 heating the enzyme
 cooling the enzyme
 salt concentration
 pH
 All of the above can affect enzyme activity.
14 .       Succinylcholine is structurally almost identical to acetylcholine but if combined with the enzyme that normally hydrolyzes acetylcholine, the enzyme is no longer able to hydrolyze acetylcholine. This suggests that _____. (5.8) [Hint]

 succinylcholine must be a competitive inhibitor with acetylcholine
 succinylcholine must regulate the activity of this enzyme by negative feedback
 the active site must have the wrong configuration to permit succinylcholine binding
 succinylcholine must be a noncompetitive inhibitor
 the activation energy barrier for succinylcholine hydrolysis is higher than for acetylcholine hydrolysis
15 .       Which of these statements about enzyme inhibitors is true? (5.8) [Hint]

 A competitive inhibitor binds to the enzyme outside the active site.
 The action of competitive inhibitors may be reversible or irreversible.
 A noncompetitive inhibitor does not change the shape of the active site.
 When the product of an enzyme or an enzyme sequence acts as its inhibitor, this is known as positive feedback.
 Antibiotics and pesticides generally do not act on enzymes, but rather affect the genetic code of their victims.
16 .       Why doesn't the antibiotic penicillin harm humans? (5.9) [Hint]

 Human cells do not have cell walls.
 The dosage given to kill bacteria is too low to harm humans.
 Penicillin attacks the nervous system.
 Penicillin attacks plasma membranes.
 Penicillin inhibits the action of acetylcholinesterase.
17 .       Why are phospholipids well suited to be the main structural components of membranes? (5.10) [Hint]

 They are completely insoluble in water.
 They form a single sheet in water.
 They form a structure in which the hydrophobic portion faces outward.
 They form a selectively permeable structure.
 They are triglycerides, which are commonly available in fatty foods.
18 .       The lipids in a cell membrane are arranged _____. (5.11) [Hint]

 between two layers of protein
 on either side of a single layer of protein
 so that the polar parts of two lipids point toward each other
 so that the nonpolar parts of two lipids point toward each other
 none of the above
19 .       Phospholipids are well suited to serve as the major component of the plasma membrane because they _____. (5.11) [Hint]

 have a water-soluble part and a water-insoluble part
 have very diverse structures and can act as receptors, enzymes, and channel molecules
 allow all needed molecules to pass through the membrane while being impermeable to any toxic substances
 contain protein
 all of the above
20 .       Which of the following best describes the general structure of a cell membrane? (5.12) [Hint]

 proteins sandwiched between two layers of phospholipid
 proteins embedded in two layers of phospholipid
 a layer of protein coating a layer of phospholipid
 phospholipids sandwiched between two layers of protein
 phospholipids embedded in two layers of protein
21 .       The membrane is referred to as a "fluid mosaic" structure. Which of the following statements is true? (5.12) [Hint]

 The fluid is phospholipid and the mosaic is carbohydrate.
 The fluid is protein and the mosaic is phospholipid.
 The mosaic comprises the carbohydrate chains on the inner surface of the membrane.
 The fluid is phospholipid and the mosaic is protein.
 The term refers to the appearance of cells in a tissue.
22 .       Stability of the plasma membrane is enhanced by _____. (5.12) [Hint]

 cholesterol molecules
 saturated triglycerides
 saturated phospholipids
 polyunsaturated triglycerides
 hydrogenation of the component lipids
23 .       All of the following are found in membranes EXCEPT _____. (5.12) [Hint]

 phospholipids
 glycolipids
 steroids
 glycoproteins
 glyconucleic acids
24 .       Which of the following functional processes results from the presence of protein within the plasma membrane? (5.13) [Hint]

 signal transduction
 attaching the membrane to the cytoskeleton
 forming junctions between adjacent cells
 enzymatic activity
 all of the above
25 .       Which of the following statements is true about passive transport? (5.14) [Hint]

 Passive transport operates independently of diffusion.
 Passive transport operates independently of concentration.
 Passive transport phenomena can never reach equilibrium.
 Passive transport does not occur in the human body.
 Passive transport requires no expenditure of cellular energy.
26 .       The movement of atoms, ions, or molecules from a region of higher concentration to regions of lower concentration is called _____. (5.14) [Hint]

 spontaneous combustion
 diffusion
 heat
 crenation
 active transport
27 .       Which one of the following statements is true about diffusion? (5.14) [Hint]

 It is very rapid over long distances.
 It requires expenditure of energy by the cell.
 It is a passive process.
 It occurs when molecules move from a region of lower concentration to a region of higher concentration.
 It requires membrane proteins.
28 .       Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell ___ because _____________. (5.14) [Hint]

 A ... the diffusion gradient there is shallower
 A ... its membrane transport proteins will not be saturated
 B ... the diffusion gradient there is steeper
 B ... the oxygen molecules inside cell B have a higher kinetic energy.
 A ... it needs the oxygen in order to revive.
29 .       Which of these statements describes what occurs in facilitated diffusion? (5.15) [Hint]

 Facilitated diffusion is another name for osmosis.
 Facilitated diffusion of solutes occurs through phospholipid pores in the membrane.
 Facilitated diffusion requires energy to drive a concentration gradient.
 Facilitated diffusion of solutes occurs through protein pores in the membrane.
 There is only one kind of protein pore for facilitated diffusion.
30 .       Which one of the following is NOT involved in facilitated diffusion? (5.15) [Hint]

 a concentration gradient
 a membrane
 a protein
 an outside energy source
 all the above are involved
31 .       The diffusion of water across a selectively permeable membrane is called _____. (5.16) [Hint]

 active transport
 osmosis
 exocytosis
 passive transport
 facilitated diffusion
32 .       The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions? (5.17) [Hint]

 a hypertonic sucrose solution
 a hypotonic sucrose solution
 a hypertonic urea solution
 a hypotonic urea solution
 pure water
33 .       Green olives may be preserved in brine, which is a 20–30% salt solution. How does this method prevent contamination by microorganisms? (5.17) [Hint]

 Bacterial cell walls are shriveled up by salt, causing the cell to burst.
 High salt concentrations lower the pH, thus inhibiting the process of glycolysis.
 High salt concentrations raise the pH, thus inhibiting the process of glycolysis.
 Bacteria can't survive in a hypotonic solution because of pressure on the cell wall.
 Bacteria can't survive in a hypertonic solution because they lose water.
34 .       Sea water is dangerous to drink because ___________. (5.17) [Hint]

 one cup of sea water contains enough sodium to poison you
 sea water is hypertonic to your body tissues and drinking it will cause you to lose water by osmosis
 sea water is isotonic to your body fluids and you will absorb too much water, causing your cells to burst
 the salt causes hypertension and you will promptly die of a stroke
 it contains toxic levels of iodine
35 .       Which of these situations accurately represents osmoregulation in organisms? (5.17) [Hint]

 Freshwater fish must all be isotonic to their environments.
 Marine animals cannot be isotonic to seawater.
 Plant cells need a hypotonic environment for their cells to stay turgid.
 Seawater is hypotonic to human cells.
 Freshwater protozoa have short life cycles because they eventually burst from taking in too much water.
36 .       If the volume of a cell increases when it is placed in an aqueous solution, that solution is said to be __________ to the cell. (5.17) [Hint]

 hypertonic
 subatomic
 isotonic
 gin and tonic
 hypotonic
37 .       Which of the following is a difference between active transport and facilitated diffusion? (5.18) [Hint]

 Active transport involves transport proteins and facilitated diffusion does not.
 Facilitated diffusion can move solutes against a concentration gradient and active transport cannot.
 Facilitated diffusion requires energy from ATP and active transport does not.
 Facilitated diffusion involves transport proteins and active transport does not.
 Active transport requires the expenditure of cellular energy, and facilitated diffusion does not.
38 .       When in solution, a molecule that moves slowly across an artificial membrane moves rapidly across a plasma membrane. This occurs regardless of whether the concentration of this molecule is higher inside or outside the cell. Using this information, which transport mechanism is most likely to be responsible for the movement of the molecule across a plasma membrane? (5.18) [Hint]

 simple diffusion
 phagocytosis
 active transport
 exocytosis
 facilitated diffusion
39 .       The transport of molecules of a particular solute from inside an animal cell across the cell membrane to the extracellular fluid always requires energy when _____. (5.18) [Hint]

 the lipid bilayer is permeable to the solute
 the concentration of the solute is higher inside the cell than outside it
 the concentration of the solute is lower inside the cell than outside it
 a transport protein is involved in the movement of the molecules
 the cytoskeleton blocks all available channels
40 .       Which one of the following is NOT needed for active transport? (5.18) [Hint]

 a concentration gradient
 a membrane
 three ions
 an outside energy source
 all the above are needed
41 .       Which of the following enables a cell to pick up and concentrate a specific kind of molecule? (5.19) [Hint]

 passive transport
 diffusion
 osmosis
 receptor-mediated endocytosis
 exocytosis
42 .       A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via _____. (5.19) [Hint]

 osmosis
 passive transport
 exocytosis
 active transport
 endocytosis
43 .       Which one of the following terms specifically refers to the intake of very large particles by cells? (5.19) [Hint]

 phagocytosis
 exocytosis
 pseudocytosis
 osmosis
 pinocytosis
44 .       Some liver cells ingest bacteria, a function probably accomplished by _____. (5.19) [Hint]

 pinocytosis
 phagocytosis
 receptor-mediated endocytosis
 exocytosis
 passive transport
45 .       Which statement best describes phagocytosis? (5.19) [Hint]

 Cells use this process to export products such as insulin or thyroxine.
 A cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole.
 Small droplets of extracellular fluid and all the dissolved solutes enter the cell by this process.
 A receptor on the plasma membrane binds to a molecule, and the cell engulfs both the receptor and the molecule.
 After entry, the endocytotic vesicle migrates to and fuses with the Golgi apparatus.
46 .       The secretion of neurotransmitters out of the nerve cell, from small vesicles at the end of the axon, can be considered an example of _____. (5.19) [Hint]

 exocytosis
 endocytosis
 phagocytosis
 pinocytosis
 osmoregulation
47 .       LDLs enter cells by means of _____. (5.20) [Hint]

 active transport
 osmosis
 receptor-mediated endocytosis
 protein-mediated exocytosis
 passive transport
48 .       Which organelles convert light energy to chemical energy? (5.21) [Hint]

 mitochondria
 ribosomes
 lysosomes
 chloroplasts
 nuclei