the rearrangement of chemical molecules within matter
the capacity to produce heat
According to the second law of thermodynamics, which of the following is true? (5.2)
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.
Which one of the following is an example of the second law of thermodynamics? (5.2)
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.
If the entropy of a system is increasing, this means that ____________. (5.2)
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
The first law of thermodynamics ____________. (5.2)
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
Which one of the following is NOT true about the second law of thermodynamics? (5.2)
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.
Cellular respiration is an example of _____. (5.3)
an endergonic reaction
an exergonic reaction
A reaction is designated as exergonic rather than endergonic when ___________. (5.3)
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
Most cellular work is accomplished by _____ energizing molecules by _____ them. (5.4)
enzymes ... activating
coenzyme ... activating
substrates ... phosphorylating
ATP ... phosphorylating
cofactors ... activating
The mechanism of enzyme action is _____. (5.5)
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
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)
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
An enzyme lowers the activation energy of a chemical reaction.
All of the above.
If the tertiary structure of an enzyme is changed _____. (5.6)
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
Which of the following environments or actions does NOT affect enzyme activity? (5.7)
heating the enzyme
cooling the enzyme
All of the above can affect enzyme activity.
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)
succinylcholine must be a competitive inhibitor with acetylcholine
succinylcholine must regulate the activity of this enzyme by
the active site must have the wrong configuration to permit succinylcholine
succinylcholine must be a noncompetitive inhibitor
the activation energy barrier for succinylcholine hydrolysis
is higher than for acetylcholine hydrolysis
Which of these statements about enzyme inhibitors is true? (5.8)
A competitive inhibitor binds to the enzyme outside the active
The action of competitive inhibitors may be reversible or irreversible.
A noncompetitive inhibitor does not change the shape of the active
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.
Why doesn't the antibiotic penicillin harm humans? (5.9)
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.
Why are phospholipids well suited to be the main structural components of membranes? (5.10)
They are completely insoluble in water.
They form a single sheet in water.
They form a structure in which the hydrophobic portion faces
They form a selectively permeable structure.
They are triglycerides, which are commonly available in fatty
The lipids in a cell membrane are arranged _____. (5.11)
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
Phospholipids are well suited to serve as the major component of the plasma membrane because they _____. (5.11)
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
all of the above
Which of the following best describes the general structure of a cell membrane? (5.12)
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
The membrane is referred to as a "fluid mosaic" structure. Which of the following statements is true? (5.12)
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.
Stability of the plasma membrane is enhanced by _____. (5.12)
hydrogenation of the component lipids
All of the following are found in membranes EXCEPT _____. (5.12)
Which of the following functional processes results from the presence of protein within the plasma membrane? (5.13)
attaching the membrane to the cytoskeleton
forming junctions between adjacent cells
all of the above
Which of the following statements is true about passive transport? (5.14)
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.
The movement of atoms, ions, or molecules from a region of higher concentration to regions of lower concentration is called
Which one of the following statements is true about diffusion? (5.14)
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.
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)
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
A ... it needs the oxygen in order to revive.
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? (5.15)
a hypertonic sucrose solution
a hypotonic sucrose solution
a hypertonic urea solution
a hypotonic urea solution
The diffusion of water across a selectively permeable membrane is called _____. (5.15)
Green olives may be preserved in brine, which is a 20–30% salt solution. How does this method prevent contamination
by microorganisms? (5.15)
Bacterial cell walls are shriveled up by salt, causing the cell
High salt concentrations lower the pH, thus inhibiting the process
High salt concentrations raise the pH, thus inhibiting the process
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
Sea water is dangerous to drink because ___________. (5.15)
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
Which of these situations accurately represents osmoregulation in organisms? (5.16)
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
Seawater is hypotonic to human cells.
Freshwater protozoa have short life cycles because they eventually
burst from taking in too much water.
If the volume of a cell increases when it is placed in an aqueous solution, that solution is said to be __________ to the
gin and tonic
Which of these statements describes what occurs in facilitated diffusion? (5.17)
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
Facilitated diffusion of solutes occurs through protein pores
in the membrane.
There is only one kind of protein pore for facilitated diffusion.
Which one of the following is NOT involved in facilitated diffusion? (5.17)
a concentration gradient
an outside energy source
all the above are involved
Which of the following is a difference between active transport and facilitated diffusion? (5.18)
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
Facilitated diffusion involves transport proteins and active
transport does not.
Active transport requires the expenditure of cellular energy,
and facilitated diffusion does not.
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)
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)
the lipid bilayer is permeable to the solute
the concentration of the solute is higher inside the cell than
the concentration of the solute is lower inside the cell than
a transport protein is involved in the movement of the molecules
the cytoskeleton blocks all available channels
Which one of the following is NOT needed for active transport? (5.18)
a concentration gradient
an outside energy source
all the above are needed
Which of the following enables a cell to pick up and concentrate a specific kind of molecule? (5.19)
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)
Which one of the following terms specifically refers to the intake of very large particles by cells? (5.19)
Some liver cells ingest bacteria, a function probably accomplished by _____. (5.19)
Which statement best describes phagocytosis? (5.19)
Cells use this process to export products such as insulin or
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.