Chapter 27—Metabolic Integration and Organ Specialization
MULTIPLE CHOICE
1. Which of the following metabolic pathways is strictly anabolic?
a.
glycolysis
b.
gluconeogenesis
c.
citric acid cycle
d.
pentose phosphate cycle
e.
-oxidation of fatty acids
2. All are major components of anabolic pathways EXCEPT:
a.
NADH.
b.
glycolysis and citric acid cycle intermediates.
c.
ATP, GTP, CTP, UTP.
d.
NADPH.
e.
all are true.
3. ____ is the principal energy source for protein synthesis, ____ for phospholipid synthesis, and ____
for polysaccharide synthesis.
a.
UTP; GTP; CTP
b.
GTP; CTP; UTP
c.
CTP; UTP; GTP
d.
UTP; CTP; GTP
e.
CTP; GTP; UTP
4. ____ and ____ are unique in that they are the only compounds whose purpose is to couple the energy-
yielding processes of ____ to the energy-consuming reactions of ____.
a.
NADH; ATP; catabolism; anabolism
b.
ATP; [FADH2]; catabolism; anabolism
c.
[FADH2]; NADH; anabolism; catabolism
d.
ATP; NADPH; catabolism; anabolism
e.
ATP; NADPH; anabolism; catabolism
5. In photoautotrophs, ____ are fed into catabolism to generate the metabolic intermediates needed to
supply ____.
a.
lipids; photorespiration
b.
proteins; photorespiration
c.
carbohydrates; anabolism
d.
carbohydrates; NADPH
e.
proteins; NADPH
6. The overall thermodynamic efficiency of metabolism is determined through reaction-coupling with:
a.
NADH oxidation.
b.
CO2 release.
c.
reduction of O2.
d.
ATP hydrolysis and synthesis.
e.
glucose oxidation.
7. Which of the following statements is true for ATP stoichiometry in metabolic pathways?
a.
It is a consequence of evolution, only.
b.
A singular number is not required, only.
c.
It results from biological adaptation, only.
d.
It cannot be predicted from any chemical considerations, only.
e.
All are true
8. The two metabolic roles served by ATP are:
a.
promoting increased reaction speed and dephosphorylation.
b.
changing both Km and Vmax.
c.
allosteric regulation and stoichiometric involvement.
d.
preventing futile cycles and changing Km.
e.
none of the above.
9. The reaction, ATP + AMP → 2ADP, is catalyzed by:
a.
adenylate phosphorylase.
b.
AMP-phosphotransferase.
c.
ADP mutase.
d.
adenylate kinase.
e.
none are true.
10. All are true for the energy charge (EC) of a cell EXCEPT:
a.
It is an index of adenylate phosphoric anhydrides.
b.
EC has a range of 0 to 1.0.
c.
It is a ratio of adenylate phosphoric anhydride bonds to total adenylate concentration.
d.
It is 1.0 when all of the adenylate is ATP.
e.
It is rapidly changed by adenylate kinase.
11. Regulatory enzymes, such as ____, in energy-producing pathways show greater activity at ____
energy charge.
a.
fructose-1,6-bisphosphatase; low
b.
acetyl-CoA carboxylase; low
c.
pyruvate kinase; high
d.
PFK-1; low
e.
none of the above
12. An energy charge (EC) of 0.9 is roughly 80% ATP, 17% ADP and 3% AMP. At this EC, ____ enzyme
activities are low and ____ enzyme activities higher.
a.
ATP generating; ATP utilizing
b.
ATP generating; NADH producing
c.
ATP utilizing; ATP generating
d.
ATP utilizing; NADH producing
e.
NADH producing; ATP generating
13. The energy charge of healthy living cells is in the neighborhood of ____.
a.
0.55-0.60
b.
0.60-0.65
c.
0.65-0.75
d.
0.75-0.85
e.
0.85-0.88
14. Which of the following enzymes is activated upon phosphorylation by AMP activated protein kinase?
a.
acetyl CoA carboxylase
b.
phosphofructokinase-2
c.
glycogen synthase
d.
3-hydroxy-3-methylglutaryl-CoA reductase
e.
none of the above
15. A constant availability of fuels in the blood is called ____ and the order of preference for fuel usage is
____.
a.
phosphorylation potential; glycogen> triacylglycerols> protein
b.
fuel dynamics; triacylglycerols> glycogen> protein
c.
metabolic regulation; triacylglycerols> glycogen> protein
d.
caloric homeostasis; glycogen> triacylglycerols> protein
e.
none are true
16. All of the following are paired with their preferred substrate EXCEPT:
a.
brain: glucose
b.
heart: fatty acids
c.
resting skeletal muscle: glucose
d.
anaerobic skeletal muscle: glucose
e.
adipose tissue: fatty acids
17. All are characteristics of brain tissue EXCEPT:
a.
2% or so of body mass.
b.
20% of oxygen consumed by brain.
c.
oxygen consumption is independent of mental activity.
d.
has no significant fuel reserves.
e.
all are true.
Garrett/Grisham 5e Test Bank 4
18. The brain prefers to use ____ as fuel, but under prolonged fasting or starvation it adapts to use ____.
a.
fatty acids; glucose
b.
glucose; -hydroxybutyrate
c.
glycogen; fatty acids
d.
glucose; fatty acids
e.
-hydroxybutyrate; amino acids
19. During fasting or starvation, the brain:
a.
converts endogenous fatty acids into -hydroxybutyrate.
b.
utilizes -hydroxybutyrate from the blood stream.
c.
utilizes amino acids for fuel from degradation of brain protein.
d.
utilizes its glycogen stores as a first responding source of fuel.
e.
all of the above.
20. Muscle contractions occur when a motor nerve impulse causes ____ release from specialized
compartments, that bind to ____, a regulatory protein initiating events that result in sliding of ____
thick filaments along ____ thin filaments.
a.
Fe++; myoglobin; actin; myosin
b.
Na+; troponin C; IGG; actin
c.
Ca++; troponin C; myosin; actin
d.
Ca++; calmodulin; PKC; PLC
e.
K+; Na+/K+ ATPase; subunit-; subunit-
21. All of the following are fuels for contracting muscles during strictly anaerobic metabolism EXCEPT:
a.
ATP.
b.
creatine phosphate.
c.
glycogen.
d.
glucose.
e.
palmitic acid.
22. During strictly anaerobic exercise, muscle cells preferentially:
a.
carboxylate pyruvate to oxaloacetate.
b.
oxidize pyruvate to acetyl-CoA.
c.
decarboxylate pyruvate to acetaldehyde.
d.
reduce pyruvate to lactate.
e.
none of the above.
23. Under strenuous aerobic exercise, which of the following would be true for skeletal muscle?
a.
only glucose will serve as a fuel source
b.
only fatty acids will serve as a fuel source
c.
both glucose and fatty acids will be used as fuel with the use of glucose increasing with
the intensity of the exercise
d.
both glucose and fatty acids will be used as fuel with the use of fatty acids increasing with
the intensity of the exercise
e.
none of the above
Garrett/Grisham 5e Test Bank 5
24. Heart muscle differs from skeletal muscle in the following ways EXCEPT:
a.
heart is completely aerobic.
b.
heart prefers fatty acids as fuel.
c.
heart has more phosphocreatine than skeletal muscle.
d.
heart has limited quantities of glycogen.
e.
all are true.
25. Energy metabolism in the heart is characterized by all of the following EXCEPT:
a.
the preferred fuel is fatty acids.
b.
it has minimal energy reserves.
c.
it is unusually rich in mitochondria.
d.
the heart consumes over 90% of the total oxygen supply during maximal physical
exertion.
e.
the range of activity is much less than that in muscle (200 fold).
26. Glucose is pivotal to adipocyte metabolism in all areas EXCEPT:
a.
forms DHAP for reduction and esterification of fatty acids.
b.
provides glucose-6-phosphate for generating NADPH from the pentose phosphate
pathway.
c.
synthesizes ketone bodies.
d.
converts glucose to fatty acids for storage and export.
e.
all are true.
27. Adipocytes lack the enzyme ____ and thus require DHAP for triacylglycerol synthesis.
a.
DHAP reductase
b.
glycerol kinase
c.
acyldihydroxyacetonephosphate transferase
d.
DHAP acyltransferase
e.
carnitine acyl transferase
28. Fatty acids are released from adipocytes when:
a.
insulin levels are high.
b.
glycerol-3-phosphate levels are high.
c.
adipose ATP levels are high.
d.
blood glucose levels are low.
e.
none are true.
29. All are characteristics associated with “brown fat” EXCEPT:
a.
high levels of mitochondria rich in cytochromes.
b.
presence of uncoupler protein-1, thermogenin, in the mitochondrial inner membrane.
c.
energy from oxidation is converted to heat.
d.
found in newborns and hibernating animals.
e.
all are characteristics.
30. All are uses of glucose-6-phosphate in liver EXCEPT:
a.
catabolized to acetyl-CoA for fatty acid biosynthesis.
b.
generate NADPH and pentoses.
c.
released as glucose to blood stream.
d.
converted to glycogen.
e.
all are true.
31. In addition to carbohydrate and lipid energy metabolism, the liver serves other purposes EXCEPT:
a.
producing insulin to regulate metabolism.
b.
converting amino acids into metabolic fuel.
c.
ketone body production.
d.
detoxification of poisons and drugs.
e.
Gluconeogenesis.
32. All are characteristics of leptin EXCEPT:
a.
it binds to hypothalamus, inhibits release of neuropeptide-Y and is thus an anorexic agent.
b.
it is a signal molecule that limits food intake and increases energy expenditure.
c.
it communicates the status of triacylglycerol levels in the adipocytes to the central nervous
system.
d.
if leptin levels are low, appetite is suppressed; and if leptin levels are high, appetite is
increased.
e.
it induces synthesis of -oxidation enzymes and increases expression of uncoupler protein-
2 (UCP-2) to increase thermogenesis.
33. Which of the following hormones that governs eating behavior is INCORRECTLY defined?
a.
insulin: stimulation of adipocyte leptin production
b.
leptin: appetite suppression when levels are high
c.
ghrelin: released from stomach in response to food to further stimulate appetite
d.
cholecystokinin: released from the intestines during eating to signal satiety
e.
all are correct
34. Ethanol metabolism in liver is characterized by all of the following EXCEPT:
a.
decreased pH levels due to lactic acidosis.
b.
two oxidation steps to convert ethanol to acetate, both reactions produce NADH.
c.
decreased gluconeogenesis activity resulting in hypoglycemia.
d.
decreased NADH/NAD+ ratio in the cell.
e.
increased acetaldehyde-protein adducts impairing protein function.
35. Which of the following comments regarding resveratrol is INCORRECT?
a.
produced in plants, particularly in grape skins, in response to stress
b.
activates SIRT1 NAD+-dependent deacetylase activity
c.
inhibits AMPK in the brain
d.
has many of the same effects as caloric restriction
e.
all of the above are correct
36. Of the following, which tissue is correctly described?
a.
brain: use of glucose and fatty acids as fuel
b.
pancreas: production of insulin and glucagon
c.
adipose tissue: storage of carbohydrates and triacylglycerols
d.
liver: overall control of metabolism through hormone production
e.
none of the above are correct
37. During the fasting phase, which of the following events occurs?
a.
release of hormones such as gastrin and cholecystokinin
b.
release of insulin by the pancreatic -cells
c.
activation of lipolysis
d.
production of glycogen
e.
none of the above
38. During the feeding phase, which of the following pathways would be inhibited in the liver?
a.
glycogen synthesis
b.
fatty acid synthesis
c.
pentose phosphate pathway
d.
gluconeogenesis
e.
none of the above
39. During prolonged fasting (more than 48 hours), which of the following would show a dramatically
increased concentration in the blood?
a.
glucose
b.
fatty acids
c.
ketone bodies
d.
lipoproteins
e.
none of the above
40. Energy balance in the cell (ATP/ADP/AMP levels) is an important factor in the metabolic pathways
we have studied. How does this regulation take place?
a.
ATP, ADP and/or AMP bind to DNA to modulate transcription of genes for enzymes
involved in metabolism
b.
ATP, ADP and/or AMP bind to enzymes involved in metabolism, allosterically changing
the enzyme activity
c.
High levels of ATP result in nonenzymatic phosphorylation of the enzymes involved in
metabolism, changing their activity
d.
High levels of ATP result in excessive production of cyclic AMP, causing activation of
pathways such as glycogenolysis and gluconeogenesis
e.
None of the above
41. Under conditions where glucose levels are high and acetyl CoA is needed for fatty acid synthesis,
which of the following pathways would NOT be active in adipose tissue?
a.
Pentose phosphate pathway
b.
Glycogen synthesis
c.
Glycolysis
d.
Glycerol synthesis from DHAP
e.
All of the above would be active
42. Leptin is an important hormone that indicates a generally satisfactory amount of metabolites available
in the body. Which of the following is true regarding leptin?
a.
Leptin is produced in adipose tissue in response to the presence of large amounts of
triacylglycerols
b.
One of the results of leptin production is the increase in thermogenesis in adipose tissue
brought about through an increase in the expression of thermogenin
c.
The primary site of leptin’s action is upon the hypothalamus where it ultimately results in
the release of norepinephrine
d.
All of the above are correct
e.
A and C are correct