Chapter 14 Digestion: Turning a Meal into Cellular Biochemicals
Matching Questions
Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
a) ATP-dependent proton pump
b) catabolism
c) hydrolyzed
d) pepsin
e) digestion
f) zymogen
g) lipases
h) anabolism
i) carbohydrates
j) lipids
k) micelle
l) enteropeptidase
1.
____________ is the first stage in the conversion of foods to energy.
2.
In digestion, proteins are ____________ into their individual 20 amino acids.
Ans: c
Section: 14.1
3.
____________ is the mechanism by which the stomach maintains a pH of around 1–2 pH units.
Ans: a
Section: 14.2
4.
____________is a protease released by the stomach for digestion of protein.
Ans: d
Section: 14.1
5.
____________ activation is a mechanism of permanently activating a protease by covalent
modification.
Ans: f
Ans: e
Section: Introduction
Chapter 14 Digestion: Turning a Meal into Cellular Biochemicals
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6.
Amylase begins the digestion of ____________ in the gut.
7.
______________ These enzymes start the hydrolysis of proteins in the small intestine.
Ans: l
8.
____________ are lipid vesicles that act to carry fats to the intestinal epithelium for absorption.
Ans: k
9.
Snake venom contains ____________, which cause hydrolysis of red blood cells.
Ans: g
Section: 14.4
10.
___________ is a set of reactions that use energy and small molecules to synthesize new
biomolecules.
Ans: h
Section: Introduction
Fill–in-the-Blank Questions
11.
The set of reactions that extract biologically useful energy from environmental sources is .
Ans: catabolism Section: Introduction
12.
One common motif in metabolism is that pathways are in common ways.
Ans: regulated Section: Introduction
13.
The pH of the stomach is important for the denaturation of proteins.
Ans: denaturation Section: 14.2
14.
The pancreas releases to neutralize the acid produced in the stomach.
Ans: sodium bicarbonate Section: 14.2
15.
A is an inactive enzyme that must be partially digested to attain full enzymatic activity.
Ans: zymogen Section: 14.1
16.
Inactive chymotrypsinogen will be hydrolyzed to become an active enzyme called .
Ans: chymotrypsin Section: 14.1
17.
Amylase digests carbohydrates by cleaving the bonds of starch.
Ans: -1,4 glycosidic Section: 14.2
Ans: i
Section: 14.3
Chapter 14 Digestion: Turning a Meal into Cellular Biochemicals
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18.
The limit dextrin is material not digested by amylase due to the .
19.
Emulsification of lipids requires what amphipathic molecule released from the gall bladder? .
Ans: bile salts Section: 14.4
20.
Micelles are important for lipid absorption across the plasma membrane, but secretion into the
lumen of the intestine and into the lymph system takes the formation of .
Ans: chylomicrons Section: 14.4
21.
Dietary fat is primarily transported from the gut to the .
Ans: lymphatic system Section: 14.4
22.
Snake venom has a high concentration of , which digests the cell membrane.
Ans: phopholipases Section: 14.4
23.
causes the release of digestive enzymes from the pancreas.
Ans: CCK Section: 14.2
24.
Bile salts are produced from the precursor .
Ans: cholesterol Section: 14.4
25.
Protein digestion leads to release of by intestinal mucosal cells into the blood for use by
other tissues.
Ans: free amino acids Section: 14.2
Multiple-Choice Questions
26.
Digestion is___________
A)
the process of breaking down large molecules in food.
B)
the salvage of metabolic intermediates.
C)
creating energy from foodstuff.
D)
the set of reactions that degrade small molecules into a few simple units.
E)
a pathway activated by steroid hormones.
Ans: A Section: Introduction
27.
You are studying a metabolic pathway and are trying to decide if it is an anabolic pathway or a
catabolic pathway. Which of the following would help diagnose this problem?
A)
Look for ATP requiring steps.
B)
Look for common intermediates.
C)
Look for enzymes under allosteric regulation
D)
Look for phagocytic activity.
E)
None of the above.
Ans: E Section: Introduction
Ans: -1,6 glycosidic bonds Section: 14.3
Chapter 14 Digestion: Turning a Meal into Cellular Biochemicals
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28.
Digestion of which of the following involves hydrolases?
A)
carbohydrates
B)
triacylglycerols
C)
proteins
D)
All of the above.
E)
A and C only.
29.
What is the significance of having transporters move amino acids from the lumen of the small
intestine into intestinal cells but anti-porters move them then into blood?
A)
The transporters are driven by a K+/H+ATPase, which provides energy to completely
deplete the intestine of all amino acids.
B)
The secondary active transport of the anti-porter moves amino acids into blood,
regardless of the blood concentrations of amino acids, keeping the intestinal cell
concentrations low.
C)
Peptidases in the intestinal cell membrane also act as amino acid transport channels
driving amino acids into intestinal cells.
D)
The transporters on the lumen side of the intestinal cell will let oligopeptides into the cell,
and the anti-porter ensures that these oligopeptides can be utilized by serum proteins.
E)
None of the above.
Ans: B Section: 14.2
30.
A digestible proton pump inhibitor would likely have the following effect:
A)
undigested protein.
B)
nucleic acid hydrolysis.
C)
loss of ATP production.
D)
pepsin activation.
E)
decreasing levels of bile salts.
Ans: A Section: 14.2
31.
The pancreas releases _________ to buffer the pH of the stomach juices.
A)
a strong base to counter the strong acid
B)
HCl
C)
NaHCO3
D)
pepsin
E)
ATPase activating protein
Ans: C Section: 14.2
32.
Pepsin requires _________ to achieve activity.
A)
low pH
B)
partial denaturation of protein
C)
zymogen activation
D)
All of the above.
E)
None of the above.
Ans: D Section: 14.2
Ans: D Sections: 14.2, 14.3, and 14.4
Chapter 14 Digestion: Turning a Meal into Cellular Biochemicals
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33.
Which of the following enzymes activates trypsin?
A)
zymogenase
B)
pepsin
C)
trypsinase
D)
enteropeptidase
E)
carboxypeptidase
34.
All of the following are pancreatic proteases except:
A)
pepsin.
B)
chymotrypsin.
C)
trypsin.
D)
carboxypeptidase.
E)
elastase.
Ans: A Section: 14.2
35.
Complex carbohydrates are absorbed:
A)
as acetyl CoA.
B)
as starch or glycogen.
C)
as glucose and simple sugars.
D)
as short 4-glucose residues.
E)
after the digestion of 1,6 bonds by amylase.
Ans: C Section: 14.3
36.
Glucose transport into intestinal epithelial cells takes place by:
A)
active transport using sodium gradient.
B)
active transport using ATP as the energy source.
C)
passive transport using the glucose gradient.
D)
secondary active transport using potassium gradient.
E)
secondary active transport using the sodium glucose cotransporter.
Ans: E Section: 14.3
37.
The result of lipase activity in digestion is:
A)
phopholipid head group hydrolysis.
B)
monoacylgycerol and two free fatty acids.
C)
bile salt formation.
D)
hydrolysis of membrane proteins.
E)
emulsion formation.
Ans: B Section: 14.4
38.
The transport of lipids in the lymph is carried out by:
A)
lipases.
B)
micelles.
C)
cholesterol bile salt binding.
D)
chylomicrons.
E)
None of the above.
Ans: D Section: 14.4
Ans: D Section: 14.2
Chapter 14 Digestion: Turning a Meal into Cellular Biochemicals
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39.
Snake venom’s poison is actually:
A)
a collection of digestive enzymes.
B)
repertory toxins.
C)
paralysis toxins and red blood cell poisons.
D)
All of the above.
E)
None of the above.
40.
Which of the following is released by the upper intestine and increases zymogen secretion?
A)
secritin
B)
pepsin
C)
cholecystekinin
D)
bile salts
E)
enteropeptidiase
Ans: C Section: 14.2
41.
What is the advantage in synthesizing enzymes as zymogens?
A)
It allows them to be packaged in chyomicrons more easily.
B)
Zymogens can be stored for rapid release when needed.
C)
Depending on the zymogen, it can be activated by the low pH in the stomach or the high
pH in the intestine.
D)
Zymogens are resistant to inactivation by kinases.
E)
Diet pills can be designed to inhibit zymogen hydrolysis.
Ans: B Section: 14.1
Short-Answer Questions
42.
How are dietary proteins, carbohydrates, and lipids digested?
monomer components, and then converted to intermediate forms for transport to their
final metabolic site.
Sections: Introduction, 14.1 – 14.5
43.
How is the release of pancreatic enzymes coordinated with digestion in the stomach?
cholecystokinin (CCK). CCK acts on the pancreas causing it to release a host of digestive
enzymes.
Section: 14.2
44.
Why is the acidification of the stomach juices important for digestion of proteins?
active at low pHs. For the proteases to bind to their substrate, the digested protein must
be partially denatured by the acidic condition of the stomach.
Section: 14.2
Ans: A Section: 14.4
Chapter 14 Digestion: Turning a Meal into Cellular Biochemicals
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45.
What would happen if an enzyme mutation occurred that seriously inhibited the activity of
amylase?
46.
What is the role of cholesterol in digestion?
Ans:
The emulsification of lipids is required for digestion and transport of fats. Crucial to this
process are the bile salts formed from cholesterol.
Section: 14.4
47.
What is a limit dextrin?
material not digested by amylase due to the 1,6 bonds
Section: 14.3
48.
Non-fat substitutes often come with a warning of runny or watery stool. What metabolic
condition is similar?
Ans:
Steatorrhea, runny stool due to excess lipids when the bile salts necessary for
emulsification and transport of lipids are inadequate.
Section: 14.4
49.
Explain the mechanism of snake bite poisons.
spreading.
Section: 14.4
50.
Why does the drug Omeprazole impact protein digestion more than lipid digestion?
Most lipases act in the small intestine where the pH is high, however pepsin, a protein
peptidase, acts in the stomach. Thus, raising stomach pH will inhibit pepsin activity.
Section: 14.2
51.
What is a chylomicron?
Ans:
A complex mixture of lipid and protein formed in the lumin of the gut to transport nacent
lipids through the lymph system.
Section: 14.4
an inability of the lumen to transport the sugars to the blood. Osmotic changes in the gut
would lead to very watery stool.
Section: 14.3