Transcript Practice Test Questions

CH 5/6 PracticeTest
The questions are in
no particular order!
Atoms and electrons can be recycled
indefinitely; energy ________.
1.
2.
3.
4.
5.
- since it can be neither created nor destroyed recycles as well
can be reorganized when plants reclaim the CO2
and water produced in respiration
must be continuously replaced because every use
of energy degrades its ability to perform useful work
can be created when needed through cellular
mechanisms
none of the choices
Patients with mitochondrial disorders share
many symptoms, such as muscle weakness,
because mitochondria ________.
1. organize the construction of muscle
protein
2. generate the ATP that is necessary for
muscle contraction
3. store and then release the oxygen used
during muscle contraction
4. facilitate the transport of glucose
across the muscle cell membrane
Which process below is correctly matched
with its cellular location?
1. glycolysis - mitochondrion
2. Krebs cycle - cytoplasm
3. lactic acid fermentation cytoplasm
4. electron transfer phosphorylation
- Golgi
5. electron transfer phosphorylation
– cytoplasm
Potential energy can be visualized
as the energy ________.
1.
2.
3.
4.
5.
of motion
of position and organization
of a falling object
of heat or thermal energy
that drives muscle contraction
In contrast to linear metabolic pathways, in
cyclic pathways, ________.
1.
2.
3.
4.
5.
the last step regenerates the same molecule as was
used in the first step of the sequence
the product molecules are arranged in closed-loop
configurations like the monosaccharides
reactants or intermediates are channeled into two or
more reaction sequences
the enzymes are positioned sequentially along a
membrane
only degradative reactions occur
Exergonic reactions produce both products
and free energy; the free energy may be
either ________.
1.
2.
3.
4.
5.
heat or light
oxidation or reduction
kinetic or potential energy
heat or muscle contraction
mechanical or chemical energy
Enzymes lower activation
energy by ________.
1.
2.
3.
4.
5.
helping substrates get together
orienting substrates into positions that favor a reaction
shutting out water molecules
inducing a fit between the enzyme and the substrate
all of the choices
Less than 50% of the energy in glucose is
converted to ATP bond energy; the remaining
energy ________.
1.
2.
3.
4.
5.
becomes activation energy for the enzymes
is stored in fat and metabolized later as needed
is carried off by CO2 and water
is used to move muscle and drive active
processes
is converted to heat
Regardless of the source of energy, virtually
all living organisms convert their energy
source into ________ before using it.
1.
2.
3.
4.
glucose
carbon dioxide
ATP
light and heat
Where in the mitochondrion are the electron
transfer chains located?
1.
2.
3.
4.
5.
in the inner compartment
embedded in the inner membrane
in the outer compartment
embedded in the outer membrane
in the mitochondrial matrix
How many ATP molecules are formed
during the Krebs cycle for each acetyl-CoA
that enters?
1.
2.
3.
4.
5.
0
1
2
4
6
What statement best
characterizes glycolysis?
1.
2.
3.
4.
glycogen, a large carbohydrate molecule, is broken
down to monosaccharides
a molecule of glucose is converted into two molecules
of pyruvate
overall, there is a net energy cost to the cell during
glycolysis
the carbon atoms in glucose are oxidized to form
carbon dioxide and water
What cofactor accepts electrons in both
glycolysis and the Krebs cycle?
1.
2.
3.
4.
5.
ATP
NADP
FAD
NAD
CoA
Substrate-level phosphorylation, in contrast
to electron transfer phosphorylation, can
occur ________.
1.
2.
3.
4.
both in the cytoplasm and the mitochondrion
under anaerobic conditions
without the aid of the enzyme ATP synthase
all of the choices are correct
After two turns of the Krebs cycle, the original glucose is
completely disassembled but the cell has gained only four
ATP. What happened to the bulk of the energy?
1.
2.
3.
4.
it has been converted to heat and is no longer
capable of producing work
glucose is a small molecule; four ATP was all the cell
could hope to recover
it was used to reduce NAD and FAD but will be
recovered during electron transfer phosphorylation
it is still contained within the carbon-oxygen bonds of
carbon dioxide
Prior to entering the Krebs cycle, pyruvate
loses ________ and is converted to ________.
1.
2.
3.
4.
5.
a water, acetyl-CoA
a carbon dioxide, oxaloacetate
a carbon dioxide, acetyl-CoA
a water, oxaloacetate
electrons, lactate
What is the role of the molecular oxygen (O2) in
aerobic respiration?
1.
2.
3.
4.
5.
it donates H's and electrons
oxygen combines with carbon from glucose to
form CO2
it transfers H's from the Krebs cycle by temporarily
forming water
oxygen accepts electrons from the electron
transfer chain and hydrogen ion to form water
oxygen is needed to synthesize ATP
The energy released during electron transfer
reactions is initially used to push ________ into
the outer compartment.
1.
2.
3.
4.
5.
electrons
NADH
hydrogen ions
oxygen
ATP
A mitochondrion has a double membrane
with the outer compartment between them.
Within the outer compartment, ________.
1.
2.
3.
4.
hydrogen ions accumulate to form the proton gradient
that drives ATP synthase
carbon dioxide accumulates and is stored until it can be
transported to the lung
the matrix containing Krebs cycle enzymes is located
the soluble electron transport enzymes are found
For glycolysis to continue in eukaryotes, NAD+ must be
regenerated. In anaerobic environments, this is
accomplished by ________, which produces ________ as
the end product(s).
1.
2.
3.
4.
fermentation, ethanol or lactic acid
phosphorylation, ATP
an exchange reaction, FADH2 and NAD+
hydrogenation, NADPH2
Substrate-level phosphorylation occurs in
only the ________stage(s) of aerobic
respiration.
1.
2.
3.
4.
5.
glycolysis and electron transfer
Krebs cycle
glycolysis
glycolysis and Krebs cycle
Krebs cycle and electron transfer
Careful measurement reveals that the cofactors coenzyme
A, NAD+, and FAD are present in cells in relatively low
concentrations. This is not surprising because ________.
1.
2.
3.
4.
5.
each becomes toxic at higher concentrations and
would damage cell metabolism
like enzymes, each can be used over and over
they are costly molecules to synthesize and cells
make them only as needed
each is degraded immediately after being used,
preventing any buildup from occurring
their roles in aerobic respiration are extremely minor
1.
2.
3.
4.
Chemical reactions that end with a net
release of energy are classified as
________.
endodermal
endothermal
endergonic
exergonic
Activation energy describes the minimum
amount of energy required ________.
1.
2.
3.
4.
for the reactants to reach the transition state and
react
before water and carbon dioxide will combine to form
glucose
to raise the temperature of a cell to within its
homeostatic range
before nutrients can cycle between producers and
consumers
How does the release of a phosphate group
from ATP provide energy for other
reactions?
1.
2.
3.
4.
the associated heat provides the activation energy to
start the reaction
the phosphate collides with one or more of the reacting
molecules
the phosphate is transferred to another molecule,
energizing it
phosphate must be added to the substrate before it will
enter an active site
Which of the following is an
example of an exergonic reaction?
1.
2.
3.
4.
6 CO2 + 6 H2O - > C6H12O6 + 6 O2
ATP - > ADP + Pi
ADP + Pi - > ATP
glycerol + 3 fatty acids - > triglyceride + H2O
Enzymes are considered
catalysts because ________.
1.
2.
3.
4.
they make reactions occur much faster than they
would on their own
like a bullet that can be fired once, the enzyme is
destroyed after each use
they are energy carriers, providing the activation
energy needed to start a reaction
all of the choices accurately describe a catalyst
Enzymes speed up reactions by
lowering the ________ energy.
1.
2.
3.
4.
activation
kinetic
mechanical
potential
That portion of the enzyme that binds
the substrate is called the ________.
1.
2.
3.
4.
allosteric activator site
transitional site
active site
substrate site
A molecule becomes reduced
when it ________.
1.
2.
3.
4.
gains an electron
is degraded into smaller products
gives up an electron
releases hydrogen ion
Pickling preserves foods by first soaking
them in strong salt solutions; how might this
delay spoilage?
1.
2.
3.
4.
bacteria probably don't like the taste of pickled foods
pickling oxidizes the foods, making them unsuitable to
bacteria
the high salt concentration denatures bacterial
enzymes
salt is an antioxidant
In feedback inhibition, ________ usually
inhibits the first enzyme in a metabolic
pathway.
1.
2.
3.
4.
the first reactant
the first intermediate
the end-product
none of the choices
In the absence of oxygen,
________.
1. energy metabolism completely ceases
and the organism dies
2. a small amount of ATP can be produced
using glycolysis
3. eukaryotic cells can use alternative
electron acceptors such as sulfur or iron
4. carbon dioxide molecules can't be
constructed and the Krebs cycle stops
How many ATPs are required for the early
stages of glucose breakdown in glycolysis?
1.
2.
3.
4.
0
1
2
4
What is the typical yield (in most cells) of ATP
from the complete aerobic respiration of
glucose?
1.
2.
3.
4.
5.
30
32
12
6
4
What is the final carbon-containing end
product of the complete aerobic respiration
of glucose?
1.
2.
3.
4.
carbon dioxide
pyruvate
starch
water
When muscle cells are deprived of oxygen,
they can continue to form ATP through
________.
1.
2.
3.
4.
5.
lactate fermentation
alcoholic fermentation
anaerobic electron transfer
sulfur reduction
both alcoholic and lactate fermentation