Practice Midterm Flashcards
Which one is not involved in emulsification of
dietary lipids in the stomach?
A. Shear force
B. Muscle contractions of stomach
C. Bile salts
D. Semi digested proteins, phospholipids and
polysaccharides
C. Bile salts
Which enzyme has the greatest contribution in
digestion of dietary triacylglycerols (TAG) in
gastrointestinal tract?
A. Lingual lipase
B. Gastric lipase
C. Pancreatic lipase
D. Lipoprotein lipase
C. Pancreatic lipase
Which one is NOT correct about pancreatic
lipase?
A. Colipase is needed for its activation
B. Hydrolyses ester bonds in triacylglycerol and
phospholipid
C. Optimal level of activity is achieved in
elevated pH
D. Bile salts are needed for its activity
B. Hydrolyses ester bonds in triacylglycerol and
phospholipid
Which transporter is involved in active
transport of glucose into enterocytes?
A. SGLT1
B. GLUT5
C. GLUT2
D. GLUT4
A. SGLT1
Which of the following fiber types is abundant
in jams and jellies?
A. Cellulose
B. Beta-glucans
C. Pectin
D. Lignin
C. Pectin
Gluconeogenesis is a pathway of glucose
__________ that is activated to ________
blood glucose levels in _______ state.
A. Production, increase, post-absorptive
B. Disposal, decrease, post-absorptive
C. Production, increase, fed
D. Disposal, decrease, fed
A. Production, increase, post-absorptive
Which one of the following is NOT a function of
apolipoproteins?
A. Stimulating enzymatic reactions that regulate
the metabolic functions of lipoproteins
B. Hydrolyzing triacylglycerol to free fatty acids
C. Stabilizing circulating lipoproteins in the
blood
D. Conferring specificity for recognition by
receptors on cells
B. Hydrolyzing triacylglycerol to free fatty acids
Ketone bodies are generated in __________
from ________.
A. Liver, pyruvate
B. Liver, acetyl-CoA
C. Brain, acetyl-CoA
D. None of the above is correct
B. Liver, acetyl-CoA
Which of the following sentences is correct?
A. Most people up-regulate endogenous
synthesis of cholesterol when dietary
cholesterol is elevated
B. Most people have non-changed
endogenous synthesis rate of cholesterol
when dietary cholesterol is elevated
C. Most people down-regulate endogenous
synthesis of cholesterol when dietary
cholesterol is elevated
D. None of the above is correct
C. Most people down-regulate endogenous
synthesis of cholesterol when dietary
cholesterol is elevated
Which of the following is a compound lipid?
A. Triacylglycerol
B. polyunsaturated fatty acid
C. Glycophosphate
D. phospholipid
D. phospholipid
Which organ produces the digestive enzymes
that are responsible for digestion of the
majority of lipids?
A. Liver
B. Pancreas
C. Gallbladder
D. Small intestine
B. Pancreas
Which of the following is NOT a function of
hydrochloric acid secretion in the stomach?
A. Activation of pepsinogen to pepsin
B. Release of disaccharides from complex
carbohydrates
C. Denaturation of proteins
D. Antibacterial action
B. Release of disaccharides from complex
carbohydrates
In the absorption of glucose and fructose,
which one of the following mechanisms is NOT
shared between glucose and fructose?
A. Facilitated diffusion between intestinal
lumen and enterocyte
B. Sodium-dependent transport into enterocyte
C. Facilitated diffusion between enterocyte and
blood stream
D. Active transport between enterocyte and
blood stream
B. Sodium-dependent transport into enterocyte
In the absorption of glucose and fructose,
which one of the following mechanisms is NOT
shared between glucose and fructose?
A. Facilitated diffusion between intestinal
lumen and enterocyte
B. Sodium-dependent transport into enterocyte
C. Facilitated diffusion between enterocyte and
blood stream
D. Active transport between enterocyte and
blood stream
B. Sodium-dependent transport into enterocyte
Amylopectin is part of:
A. Lignin
B. Polyols
C. Starch
D. Inulin
C. Starch
Plant sterols are suggested to help reduce blood
cholesterol levels. What is the suggested
mechanism for this beneficial effect?
A. Plant sterols reduce cholesterol absorption
by competing with cholesterol for uptake
into micelles thereby reducing cholesterol
absorption.
B. Plant sterols enhance bile acid excretion
leading to reduced recycling of bile acid and
thus enhanced bile acid formation from
blood cholesterol.
C. Plant sterols displace cholesterol in the
formation of VLDL.
D. Plant sterols suppress hunger resulting in
reduced food intake and cholesterol
ingestion
A. Plant sterols reduce cholesterol absorption
by competing with cholesterol for uptake
into micelles thereby reducing cholesterol
absorption.
T/F: Viscous gel-forming fibers improve micelle
formation and enterohepatic recirculation of
bile.
FALSE
Gel-forming fibers diminish absorption of lipids
and increase fecal bile excretion.
T/F:The main function of LDL is cholesterol delivery
to different tissues
TRUE
T/F:Only anaerobic glycolysis is possible in red blood
cells because of lack of delivery of oxygen to
these cells
FALSE
Red blood cells lack mitochondria.
LECTURE 12 – SLIDE 44
T/F:Hormones glucagon and epinephrine inhibit
“hormone-sensitive lipase” in adipocytes to
increase hydrolysis of triacylglycerols stored in
this tissue.
FALSE
Glucagon and epinephrine activate “hormone-
sensitive lipase” to stimulate hydrolysis of TAG.
LECTURE 12 – SLIDE 46
T/F: Digestion of carbohydrates starts in the mouth
by the action of salivary alpha-amylase which
hydrolyzes alpha-(1-4) glycosidic bonds in starch
TRUE
T/F:Insulin activates glycogenesis pathway in muscle
when blood glucose levels are low.
FALSE
Insulin activates glycogenesis when blood
glucose levels are high
T/F: Succinate dehydrogenase is responsible for
production of ATP in TCA cycle through
substrate-level phosphorylation
FALSE
Succinyl-CoA synthetase produces ATP in TCA
cycle through substrate-level phosphorylation.
Succinate dehydrogenase produces FADH2
_________ is a (an) ____________ that stimulates the gallbladder to contract and release the bile into the duodenum.
Cholecystokinin, enzyme
Cholecystokinin, hormone
Acetylcholine, enzyme
Acetylcholine, hormone
Cholecystokinin, hormone
If lactate generated in the muscle tissue by anaerobic glycolysis is transported to the liver to be converted to glucose, and is then subsequently transported back to the muscle cells (as glucose) which pathway has been completed?
Krebs Cycle
Cori Cycle
Enterohepatic Cycle
Lactate Cycle
Cori Cycle
The glucose transporter GLUT4 is insulin dependent and crucial for glucose uptake into
Adipose tissue
Erythrocytes
Liver
Brain
Adipose tissue
T/F: The process of gluconeogenesis occurs partially in the mitochondria, and partially in the cytosol.
TRUE
Which of the following enzymes catalyzes a regulatory reaction within the aerobic glycolysis pathway in the liver?
Glucokinase
Hexokinase
Phosphofructokinase
Only Glucokinase and Phosphofructokinase are correct
All above answers are correct
Only Glucokinase and Phosphofructokinase are correct
T/F: Gluconeogenesis in the muscle and liver facilitate blood glucose homeostasis during exercise.
FALSE
Which organ produces and releases enzymes which are responsible for the digestion of the majority of macronutrients?
Liver
Pancreas
Gallbladder
Small intestine
Pancreas
Glycogenolysis is ________________________.
the breakdown of glycogen
the formation of glycogen
the oxidation of glucose
the formation of glucose from galactose
the breakdown of glycogen
The hormone that stimulates glycogen formation in the muscle and liver is:
cortisol
epinephrine
insulin
glucagon
insulin
T/F: Acetyl-CoA can negatively modulate the activity of the rate-limiting allosteric enzyme pyruvate kinase in glycolysis.
TRUE
Glycogen stored in muscle does not contribute directly to blood glucose levels because:
Muscle lacks glucose-6-phosphatase to convert glucose-6-phosphate to free glucose
Muscle lacks glucokinase to convert glucose-6-phosphate to free glucose
It is not true, glycogen in muscle contributes to blood glucose levels
Muscle lacks glucose-6-phosphatase to convert glucose-6-phosphate to free glucose
Which of the following metabolites is not a gluconeogenic precursor?
Acetyl-CoA
Alanine
Pyruvate
Glycerol
Acetyl-CoA
Fructose has the chemical structure of
a ketopentose.
a ketohexose.
an aldohexose.
an aldopentose.
a ketohexose.
T/F: Glycemic load (GL) takes into account a portion size in contrary to glycemic index (GI), which can explain high GL and low GI for carrots.
FALSE
Compared to glucose, fructose is absorbed by facilitated diffusion only and does not require active transport into the intestinal cell. This is because:
Fructose has a much higher affinity to GLUT5 than glucose has to GLUT2.
Fructose can be transported to the intestinal cell independent of the concentration gradient
The concentration of fructose in the intestinal cell is always lower than in the intestinal lumen.
Fructose is phosphorylated in the intestinal cell to allow continuous absorption of fructose molecules.
The concentration of fructose in the intestinal cell is always lower than in the intestinal lumen.
The consumption of hot boiled potato only (no side dishes) compared to the consumption of cold boiled potato only will lead to _________________ in the first two hours after food intake.
a prolonged increase in blood glucose concentrations
a slower increase in blood glucose concentrations
a similar increase in blood glucose concentrations
a faster increase in blood glucose concentrations
a faster increase in blood glucose concentrations
Glucose can be absorbed in the small intestine by different mechanisms. Which glucose transporter allows the absorption of glucose into the enterocytes against a concentration gradient?
GLUT2
GLUT1
SGLT-1
SGLT-2
SGLT-1
Gluconeogenesis is the formation of glucose from non-carbohydrate sources. The function of this pathway however differs between tissues. Which of the following sentences is correct?
In the liver, glucose is formed of amino acids only and serves for maintenance of glycogen stores.
The muscle forms glucose primarily for entry into the hexosemonophosphate shunt.
Glucose formed in the liver from gluconeogenic precursors is used to maintain normal blood glucose levels.
Gluconeogenesis does not exist in muscle tissue because muscle tissue lacks the enzyme fructose-1,6-bisphosphatase.
Glucose formed in the liver from gluconeogenic precursors is used to maintain normal blood glucose levels.
Two hormones that stimulate glycogenolysis in the muscle and liver are __________________.
secretin and epinephrine
epinephrine and glucagon
insulin and epinephrine
glucagon and insulin
epinephrine and glucagon
The digestion of disaccharides mainly occurs in the _________.
Mouth
Stomach
Lumen of small intestine
Brush border membrane
Brush border membrane
Erythrocytes have a high rate of anaerobic glycolysis. Why?
Erythrocytes in venous blood lack oxygen for aerobic glycolysis.
Erythrocytes lack amino acids that are important precursors for the TCA cycle.
Erythrocytes lack mitochondria to fully oxidize glucose.
Erythrocytes have a high rate of anaerobic glycolysis because it releases large amounts of energy.
Erythrocytes lack mitochondria to fully oxidize glucose.
The enzyme that digests the majority of ingested complex carbohydrates is:
Salivary alpha 1-4 amylase
Pancreatic alpha 1-4 amylase
Duodenal alpha 1-4 amylase
Salivary alpha 1-6 amylase
Pancreatic alpha 1-4 amylase
Most of the digestive enzymes produced by the intestinal mucosal cells function
in the stomach.
in the intestinal lumen.
at the brush border.
within the cytoplasm of the enterocytes.
at the brush border.
Glucagon stimulates hepatic gluconeogenesis and suppresses glycolysis by reducing the concentration of _________, a positive modulator of phosphofructokinase.
fructose-2,6-bisphosphate
fructose-6-phosphate
glucose-6-phosphate
glucose-1-phosphate
fructose-2,6-bisphosphate
In lipid digestion and absorption processes, polymolecular aggregates called mixed micelles are small enough to…:
Enter the enterocytes
Stabilize circulating lipoproteins in the lymphatic system
Enter the intramicrovillus spaces to interact with the brush border
Confer specificity for recognition by receptors on cells
Enter the intramicrovillus spaces to interact with the brush border
In stages of impaired lipid digestion (e.g., in preterm infants), energy requirements from dietary lipid can be compensated for by enriching diets (e.g., infant formulas) with:
Docosahexaenoic acid
Medium-chain fatty acids
Polyunsaturated fatty acids
Long-chain fatty acids
Medium-chain fatty acids
EPA and DHA can be synthesized in human body from:
linoleic acid
arachidonic acid
alpha-linolenic acid
palmitic acid
alpha-linolenic acid
After a high-fat meal, we feel ‘full’. The high satiety value from fat can be explained by many factors. One of them is hormonal. Which one of the following hormones has been suggested to be secreted after a high-fat meal and contribute to feeling ‘full?
Ghrelin
Cholecystokinin
Enterogastrone
Glucagon
Enterogastrone
T/F; All signaling molecules synthesized from omega-6 unsaturated fatty acids have anti-inflammatory effects.
FALES
Lingual lipase contributes to lipid digestion. Which one of the following statements about the characteristics of lingual lipase is CORRECT:
Lingual lipase preferentially cleaves the sn-2 fatty acids
Lingual lipase is not active in infants
Lingual lipase preferentially cleaves short- and medium chain fatty acids
Lingual lipase contributes to lipid digestion in the mouth (10% of total lipid digestion)
Lingual lipase preferentially cleaves short- and medium chain fatty acids
Dietary fat quality can have an impact on blood cholesterol profile. Altering blood cholesterol levels can lower the risk of atherosclerosis and cardiovascular disease. Which of the following statements reflects our current state of knowledge of the good or bad effects of fatty acids?
Polyunsaturated fatty acids contribute to improved cholesterol profile by increasing LDL cholesterol.
Increasing monounsaturated fatty acid intake decreases LDL cholesterol but increases HDL cholesterol.
Increasing trans-fatty acid intake increases HDL - the “good cholesterol”.
Reducing saturated fatty acids reduces LDL cholesterol but also HDL cholesterol and is therefore not beneficial in reducing the risk of cardiovascular disease.
Increasing monounsaturated fatty acid intake decreases LDL cholesterol but increases HDL cholesterol.
Cholesterol is an essential precursor for synthesis of important biologically active compounds (e.g., vitamin D and steroid hormones).
Therefore…
… cholesterol is an essential nutrient.
… our body is able to synthesize it from scratch.
… we should lower cholesterol intake.
… cholesterol intake is regarded as risk factor for cardiovascular disease.
… our body is able to synthesize it from scratch.
Carbon-carbon double bonds in the trans form of a given fatty acid
Result in a kinking of the fatty acid into a U-shape.
Extend the fatty acid into a linear shape.
Are required to create saturated fatty acids.
Are the hallmark of essential fatty acids.
Extend the fatty acid into a linear shape.
Fatty acids in human body are synthesized from:
Cholesterol
Amino groups
Hormones
Acetyl-CoA
Acetyl-CoA
All of the following are functions of apolipoproteins EXCEPT:
Stimulating enzymatic reactions that regulate the metabolic functions of lipoproteins
Stabilizing circulating lipoproteins in the blood by being a part of their outer membrane
Decreasing the density of the lipoprotein
Conferring specificity for recognition by receptors on cells
Decreasing the density of the lipoprotein
hich organ provides the major site for lipoprotein formation from endogenously derived lipids:
Intestine
Gallbladder
Liver
Pancreas
Liver
Essential fatty acids are:
Arachidonic acid and docosahexaenoic acid
Eicosapentaenoic acid and alpha-linolenic acid
Alpha-linolenic acid and linoleic acid
Docosahexaenoic acid and eicosapentaenoic acid
Alpha-linolenic acid and linoleic acid
Which group of the following lipoproteins is normally NOT present in blood in the fasting state?
VLDL
LDL
HDL
Chylomicrons
Chylomicrons
Why are the oligosaccharides raffinose, stachyose, and verbascose digested by fermentation and not by degradation into monosaccharides?
Because they are preferred substrates for bacterial growth.
Because they are not accessible to the gastric α-amylase.
Because humans don’t have the enzymes required to digest them.
Because hydrochloric acid in the stomach makes them inaccessible for digestive enzymes.
Because humans don’t have the enzymes required to digest them.
Which type of fiber is abundantly present in edible seeds on the surface of strawberries?
resistant starch
lignin
cellulose
beta-glucans
lignin
Which of the following is a biological role of phospholipids?
Structural support for cell membranes
Energy storage
Insulation
Transport of lipids in the bloodstream
Structural support for cell membranes
Most of the energy in our body is stored as fat. What is the storage form of fat in our body?
Cholesterol esters
Glycogen
Phospholipids
Triacylglycerols
Triacylglycerols
T/F: Lipoprotein lipase is responsible for unloading the content of both chylomicrons and VLDL at peripheral tissues.
TRUE
Plant sterols are suggested to help reduce blood cholesterol levels. What is the suggested mechanism for this beneficial effect?
Plant sterol rich food products contain low amounts of cholesterol.
Plant sterols are absorbed instead of cholesterol but do not impact LDL or HDL formation.
Plant sterols reduce cholesterol absorption because they displace cholesterol from mixed micelles.
Plant sterols increase satiety which leads to reduced food intake and thereby lowering the cholesterol intake and absorption.
Plant sterols reduce cholesterol absorption because they displace cholesterol from mixed micelles.
Certain types of lipids are responsible for conferring structural properties to medullary sheaths found in nervous tissue. One of them is:
Glucosidase
Lecithin
Ganglioside
Eicosanoid
Ganglioside
Which one of the following statements about cellulose is correct?
Cellulose is a minor component of plant cell walls.
Cellulose is water insoluble.
Cellulose is only a dietary fiber, not a functional fiber.
Bacteria ferment cellulose at extremely high rates.
Cellulose is water insoluble.
Which of the following statements is FALSE? Short-chain fatty acids produced by colonic bacteria during fermentation of fiber exert diverse effects including:
can provide a source of energy for various body tissues
are protective in colon cancer
help to emulsify lipids
inhibit cholesterol and fatty acid synthesis
help to emulsify lipids
The key to the cell’s internalization of low density lipoprotein is the interaction between apoB-100 and…
Lipoprotein lipase
Cholesterol acyltransferase
HMG CoA reductase
LDL receptor
LDL receptor
high-fiber diet is suggested to help prevent obesity. Taking into account physiological effects of fiber, which one of the following answers describes the effects of fiber that are underlying mechanisms between high fiber intake and obesity prevention?
Reduced absorption of macronutrients and increased formation of gas
Increased satiety and reduced absorption of macronutrients
Increased satiety and decreased formation of short-chain fatty acids
Increased nutrient utilization and increased pancreatic secretions
Increased satiety and reduced absorption of macronutrients
