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Chapter 5

STUDY
PLAY
The ultimate source of nearly all energy available to life on Earth is
sunlight.
Which one of the following is not a
function of the plasma membrane? The plasma membrane
is the control center of the cell
The act of a white blood cell engulfing a bacterium is
phagocytosis.
In lab, you use a special balloon that is
permeable to water but not sucrose to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. Which of the following will occur?
Water will leave the balloon
In the reaction A → B + C + heat,
the potential energy of the products is less than that of the reactant
When two aqueous solutions that differ
in solute concentration are placed on either side of a semipermeable membrane, and osmosis is allowed to take place, the water will
exhibit a net movement to the side with lower water concentration
Bacterial production of the enzymes
needed for the synthesis of the amino acid tryptophan declines with increasing levels of tryptophan and increases as tryptophan levels decline. This is an example of
feedback inhibition
The active site of an enzyme is
the region of an enzyme that attaches to a substrate.
Phagocytosis is to eating as pinocytosis
is to
drinking.
Small, nonpolar, hydrophobic molecules
such as fatty acids
easily pass through a membrane's lipid bilayer.
A steer must eat at least 100 pounds of grain to gain less than 10 pounds of muscle tissue. This illustrates
the second law of thermodynamics.
Which of the following can affect the rate
of an enzyme-catalyzed reaction?
All of the choices are correct.
Which of the following is not a true
statement about diffusion? Diffusion
occurs when particles spread from areas where they are less concentrated to areas
where they are more concentrated
According to __________, energy cannot
be created or destroyed.
the first law of thermodynamics
The more heat released by a reaction, the
greater the increase in entropy.
Diffusion does not require the cell to
expend ATP. Therefore, diffusion is considered a type of
passive transport.
The cholesterol associated with cell membranes
helps to stabilize the cell membrane at body temperature.
Kinetic energy differs from chemical
energy in that
kinetic energy is the energy of a moving object, whereas chemical energy is the potential
energy of molecules.
When an enzyme catalyzes a reaction
it lowers the activation energy of the reaction.
Osmosis can be defined as
the diffusion of water across a membrane
Which one of the following is true?
Enzymes catalyze specific reactions.
When physicians perform an organ
transplant, they choose a donor whose tissues match those of the recipient as closely as possible. Which of the following cell components are being matched?
cell-surface carbohydrates
Most of a cell's enzymes are
proteins
The fluid mosaic model describes the
plasma membrane as consisting of
individual proteins and phospholipids that can drift in a phospholipid bilayer.
Which one of the following processes could result in the net movement of a substance into a cell, if the substance is more concentrated in the cell than in the surroundings?
active transport
Which of the following substances could
be a cofactor?
a zinc atom
Which of the following energy transfers
is/are possible in living systems?
All of the choices are correct.
What is the basic difference between
exergonic and endergonic reactions?
Exergonic reactions release energy; endergonic reactions absorb it.
Anything that prevents ATP formation will
most likely
result in cell death
Living systems
decrease their entropy while increasing the entropy of the universe.
If placed in tap water, an animal cell will
undergo lysis, whereas a plant cell will not. What accounts for this difference?
the relative inelasticity and strength of the plant cell wall
Heating inactivates enzymes by
changing the enzyme's three-dimensional shape.
Plasma membranes are selectively
permeable. This means that
the plasma membrane allows some substances to enter or leave a cell more easily
than others.
What type of bond joins the phosphates of ATP?
covalent
Substrates bind to an enzyme's __________ site.
active
The molecules responsible for
membrane transport are
proteins.
Ultimately, nearly all animals are
dependent on __________ as their source of energy.
photosynthesis
Which one of the following is a typical
feature of an ATP-driven active transport mechanism?
None of the choices are correct
Membrane phospholipids
None of the choices are correct.
A child is brought to the hospital with a
fever of 107°F. Doctors immediately order an ice bath to lower the child's temperature. Which explanation offers the most logical reason for this action?
Elevated body temperatures may denature enzymes. This would interfere with the cell's
abilities to catalyze various reactions
Most of the functions of a cell membrane
are performed by
proteins
Glucose molecules provide energy to
power the swimming motion of sperm. In this example, the sperm are changing
chemical energy into kinetic energy
The energy required to initiate an
exergonic reaction is called
the energy of activation.
The transfer of a phosphate group to a
molecule or compound is called
phosphorylation.
Where in are eukaryotic cell enzymes
typically located?
in plasma membranes and inside organelles
Which one of the following processes is
endergonic?
the synthesis of glucose from carbon dioxide and water
Active transport
All of the choices are correct.
Which one of the following is true about
the ATP molecule?
It contains a nitrogenous base molecule called adenine
Some protozoans have special
organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment
is hypotonic to the protozoan.
Which one of the following is false?
Enzymes are used up in chemical reactions.