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Q:
What type of resistant starch is formed during food processing such as the cooking and cooling of starchy foods?
a. RS1
b. RS2
c. RS3
d. RS4
Q:
Which of the following fibers stimulate the growth of bifidobacteria and thus are considered prebiotics?
a. lignins
b. fructans
c. beta-glucans
d. cellulose
Q:
Common food sources of fructans are _____.
a. strawberries, apples, and citrus fruits
b. whole grains
c. chicory, onions, and Jerusalem artichokes
d. legumes
Q:
What are the homopolymers of glucopyranose found in cereal brans such as oats and barley that are effective in reducing serum cholesterol?
a. beta-glucans
b. fructans
c. fructooligosaccharides
d. chitin
Q:
What are the hydrocolloids that are secreted at a site of injury on a plant or surround the endosperm of some seeds and that are used as thickening agents?
a. lignin
b. cellulose
c. pectins
d. gums
Q:
Name a water-soluble, gel-forming fiber that functions in the plant as intracellular cement and that is used commercially to make jellies and to provide fiber in enteral formulas.
a. lignin
b. gum
c. pectin
d. cellulose
Q:
What is the primary noncarbohydrate component of fiber?
a. gums
b. hemicellulose
c. lignin
d. cellulose
Q:
Pectins are part of the cell wall and middle lamella and are _____.
a. water soluble
b. gel forming
c. stable at acidic pHs
d. all of the above
Q:
Which fiber component is provided primarily by the outer layers of cereal grains?
a. lignin
b. pectin
c. fructans
d. cellulose
Q:
Which group of high-fiber foods contains the greatest quantities of hemicellulose?
a. legumes
b. whole-grain cereals and bran
c. fruits
d. vegetables
Q:
Processed foods that may have cellulose purified from wood added to them include all of the following EXCEPT _____.
a. canned green beans
b. cake mixes
c. sandwich spreads
d. fruit juice mixes
Q:
Dietary fibers are mainly provided by
a. proteins that have been heated with sugars.
b. plant cell walls.
c. chitin and chitosan.
d. plant gums.
Q:
Functional fiber is currently defined as
a. carbohydrates and lignin that are nondigestible by human enzymes and are intact and intrinsic in plants.
b. carbohydrates that are nondigestible by human enzymes, have been isolated, extracted or manufactured, and have been shown to have beneficial physiological effects in humans.
c. all dietary fiber.
d. the same as crude fiber.
Q:
Dietary fiber is currently defined as
a. carbohydrates and lignin that are nondigestible by human enzymes and are intact and intrinsic in plants.
b. carbohydrates that are nondigestible by human enzymes, have been isolated, extracted or manufactured, and have been shown to have beneficial physiological effects in humans.
c. crude fiber.
d. the same as functional fiber.
Q:
True/FalseThe reason we require the malate-aspartate shuttle is because NADH cannot enter the mitochondria to donate its electrons to the electron transport chain.
Q:
Briefly discuss how high-fructose corn syrup is made and why it contains the same amount of fructose as sucrose or honey and less fructose than apple juice.
Q:
When fructose-sweetened beverages are consumed in research studies, plasma triglycerides levels are:
a. always elevated.
b. sometimes elevated.
c. never elevated.
d. elevated only in women.
Q:
Which tissue metabolizes fructose?
a. muscle
b. adipose tissue
c. liver
d. all of these
Q:
The fructose : glucose ratio of high-fructose corn syrup is approximately _____.
a. 100:1
b. 80:20
c. 50:50
d. 25:75
Q:
Which statement is true?
a. The use of high-fructose corn syrup in U.S. products increased between 1970 and 1998, but has since leveled off.
b. Between 2000 and 2010, use of high-fructose corn syrup in the U.S. food supply was about twice the use of table sugars.
c. High-fructose corn syrup and corn syrup are two names for the same product.
d. All high-fructose corn syrup sold in the U.S. is made from corn.
Q:
Describe the symport mechanism involving glucose and the NA+/K+-ATPase pump.
Q:
Alcohol consumption increases the NADH/NAD+ ratiothat is, alcohol metabolism results in an increase of NADH and a depletion of NAD+. In terms of changes in enzyme activities, describe how alcohol consumption via the change in the NADH/NAD+ ratio decreases the oxidation of carbohydrates.
Q:
Describe the process by which high levels of muscle lactate, produced by oxygen debt from exercise, are controlled/diminished by gluconeogenic action of the liver.
Q:
Uncouplers are molecules that allow protons to leak back into the mitochondrial matrix so that the proton gradient between the intermembrane space and the matrix of the mitochondria is insufficient to produce ATP. Explain how 2,4-dinitrophenol, a poisonous uncoupler, causes elevated body temperature.
Q:
Discuss the chemiosmotic theory of the mechanism by which the energy from electron transport is used to synthesize ATP.
Q:
In anaerobic conditions the NADH produced in glycolysis is not reoxidized by oxygen in the mitochondria but is oxidized to NAD in the cytoplasm by an enzyme. What is the enzyme and what is the importance of this reaction for conditions of low oxygen level?
Q:
Following a meal containing carbohydrates, glucose enters the bloodstream and increases the circulating blood glucose concentration. Describe the changes in the levels of hormonal regulators (insulin, glucagon, and cortisol) in response to this high glucose concentration and their major functions in lowering glucose levels in the bloodstream back to normal.
Q:
Discuss why sucrose, ordinarily an easily digested carbohydrate, might present problems of flatulence and diarrhea in individuals with severe inflammatory bowel disease.
Q:
Enzymes are regulated by induction, covalent regulation (a form of posttranslational modification), and allosteric modification. Pick out THREE (3) of your favorite enzymes from the enzymes involved in glycolysis, the TCA cycle, gluconeogenesis, glycogenesis, or glycogenolysis. Then, indicate: the reaction that the enzyme catalyzes; what tissue(s) this occurs in; how it is regulated (via one of the mechanisms listed above); and what signals are involved in its regulation. NOTE: Long answers are unnecessarythis can be done in a relatively short single sentence.
Q:
Glycogenesis, glycogenolysis, gluconeogenesis, and glycolysis are tissue-specificthat is, either the pathway or certain aspects of the pathway are different for different tissues. Pick ONE metabolic process and describe what occurs, including what tissues are involved and any tissue-specific differences. Make sure to indicate any and all signals involved in this process.
Q:
A number of metabolic pathways have a problem in that certain components required for them to function are found in either the cytosol or the mitochondria, and some intermediates cannot cross the membrane. This requires that certain compounds be shuttled from one compartment to the other. Explain this shuttling process for either: (a) glycolysis/TCA cycle OR (b) gluconeogenesis. Your answer should include: what needs to be shuttled, why it needs to be shuttled, and how this is accomplished.
Q:
Often you will hear the statement, "Insulin is important for the uptake of blood glucose by all tissues." What is wrong with this statement? Be specific.
Q:
Pyruvate dehydrogenase is positively modulated by _____ and _____.
Q:
ADP can positively modulate the activity of the rate-limiting allosteric enzyme in glycolysis, _____.
Q:
Glucokinase located in the _____ is induced by insulin, and hexokinase located in the _____ is inhibited by glucose-6-phosphate.
Q:
When dietary intake of carbohydrate is reduced or blood glucose concentration declines, the pathway that is stimulated in the liver by glucagon and corticosteroids is called _____. Four non-carbohydrate precursors that serve as substrates for this pathway are: _____, _____, _____ and amino acids.
Q:
A homopolysaccharide that is important as a storage compound in human body is _____, which can be enzymatically dismantled to produce _____.
Q:
Match the enzymes with the pathway in which they function in carbohydrate metabolism.
Enzyme
1) Phosphofructokinase
2) Pyruvate carboxylase
3) Glycogen phosphorylase
4) Glucose-6-phosphate dehydrogenase
5) Branching enzyme
Pathway
a. glycogenesis
b. glycolysis
c. gluconeogenesis
d. glycogenolysis
e. pentose phosphate pathway
Q:
True/False
Active transport requires energy for the Na-K pump to transport Na out of the cell, thereby driving the transport of something else (e.g., glucose) when the Na re-enters the cell down its concentration gradient.
Q:
True/FalseAll cells have mitochondria, which act as the main site for ATP production.
Q:
True/FalseBecause they do not have mitochondria, red blood cells generate a lot of lactate from glycolysis, which they in turn must convert into glucose to meet their energy needs.
Q:
True/False
Although many enzymes in a given pathway are bidirectional, often the key enzymes are unidirectional (i.e., only work in one direction).
Q:
True/False
The Cori cycle would be active under anaerobic conditions, such as excessive muscle exertion.
Q:
True/FalseThe signal for glycogenolysis to occur in liver and muscle is glucagon, which is secreted by the pancreas in response to low blood glucose levels.
Q:
True/FalseThe muscle is an important tissue in gluconeogenesis, because it can use amino acids from protein breakdown and convert them to glucose, which it then secretes into the circulation for other tissues.
Q:
True/False
The process of gluconeogenesis occurs partially in the mitochondria, and partially in the cytosol.
Q:
True/False
Glucose is transported from the lumen into the enterocyte by active transport using SGLT1 protein, which also requires Na as a co-transporter.
Q:
True/FalsePhosphorylation of a protein always results in its inactivation, whereas dephosphorylation activates it.
Q:
True/FalseThe purpose of the pentose phosphate pathway is to generate ribose, for nucleic acid synthesis, and NAD, for oxidizing power.
Q:
True/FalseThe abundance of GLUT4 is increased by induction in response to a high-CHO meal.
Q:
Glucagon stimulates hepatic gluconeogenesis and suppresses glycolysis by reducing the concentration of _____, a positive modulator of phosphofructokinase.
a. fructose-2,6-bisphosphate
b. fructose-1,6-bisphosphate
c. glucose-6-phosphate
d. glucose-1-phosphate
Q:
All of the following enzymes are negatively regulated (allosterically inhibited) by increasing levels of ATP EXCEPT _____.
a. phosphofructokinase
b. pyruvate dehydrogenase complex
c. hexokinase
d. citrate synthase
Q:
If an individual with no blood sugar abnormalities when eating regularly presented with severe hypoglycemia after 30 hours of fasting, which enzyme would you suspect might be malfunctioning?
a. phosphofructokinase
b. pyruvate kinase
c. fructose-1,6-bisphosphatase
d. glucose-6-phosphatase
Q:
Muscle lactate is converted to glucose in the liver and returned to the muscle by means of the _____.
a. malate-aspartate shuttle
b. electron transport chain
c. Cori cycle
d. pentose phosphate pathway
Q:
All of the following are substrates for gluconeogenesis EXCEPT
a. fatty acids.
b. lactate.
c. glycerol.
d. glucogenic amino acids.
Q:
Gluconeogenesis is essentially the reversal of which pathway?
a. glycogenesis
b. glycolysis
c. TCA cycle
d. lipogenesis
Q:
Which tissue has the least activity of the pentose phosphate pathway?
a. liver
b. adrenal cortex
c. mammary gland
d. skeletal muscle
Q:
The purpose of the hexose monophosphate shunt is to produce
a. pentose phosphates and NADPH.
b. DNA and RNA.
c. fatty acids.
d. reducing substrates.
Q:
The enzyme ATP synthase is believed to catalyze the formation of ATP, as described by the _____ theory.
a. leakage
b. hydrogen pump
c. protein channel
d. chemiosmotic
Q:
Electrons carried by one mole NADH + H+ enter the electron transport chain at Complex I and generate _____ mole(s) ATP as they are sequentially oxidized.
a. 0.5
b. 1.5
c. 2.5
d. 3.5
Q:
Electron flow through Complexes I, III, and IV is accompanied by the translocation of protons
a. from the matrix into the intermembrane space.
b. from the iron-sulfur centers into the cytosol.
c. from cytochrome c to cytochrome c1.
d. from cytochrome b to the iron-sulfur center.
Q:
During the end reaction of the electron transport chain, molecular oxygen becomes _____.
a. oxidized to carbon dioxide
b. reduced to water
c. NADH + H+
d. FADH2
Q:
The formation of ATP by compounds with a more negative phosphate group transfer potential than -7,300 cal is called _____.
a. transfer phosphorylation
b. oxidative phosphorylation
c. coupled reactions
d. substrate-level phosphorylation
Q:
Alcohol in beverages is degraded mainly in the liver cytosol with the production of one NADH for each ethanol molecule. Predict what effect consumption of alcohol would have on the activity of the liver malate-aspartate shuttle.
a. no change
b. increased
c. decreased
d. reversed
Q:
When oxygen is present in a tissue, less glucose is metabolized to pyruvate. Why?
a. Less lactate can accumulate in the presence of oxygen.
b. ATP accumulates and inhibits phosphofructokinase.
c. Metabolism slows in the presence of oxygen.
d. More glucose is converted to glycogen.
Q:
In the complete oxidation of 1 mol of glucose, how many ATPs are formed?
a. 4-6
b. 8-12
c. 18-24
d. 32-38
Q:
Under anaerobic conditions within a cell, how many net ATPs are formed from one glucose molecule by substrate-level phosphorylation?
a. one
b. two
c. four
d. six
Q:
In the _____ galactose is eventually converted to _____.
a. hepatocyte, glucose
b. Kupffer cell, fructose
c. enterocyte, glucose
d. chylomicron, glucose
Q:
In what organelle are the enzymes that catalyze the citric acid cycle located?
a. cytoplasmic matrix
b. endoplasmic reticulum
c. mitochondrion
d. lysosome
Q:
Two hormones that stimulate glycogenolysis in the muscle and liver, respectively, are _____.
a. cortisol and epinephrine
b. epinephrine and glucagon
c. insulin and epinephrine
d. glucagon and insulin
Q:
In which cellular site is most of the energy released when carbohydrates are oxidized to carbon dioxide and water?
a. cytoplast
b. reticuloendothelium
c. Golgi body
d. mitochondrion
Q:
In what part of the cell does glycolysis occur?
a. mitochondrion
b. cytosol
c. nucleus
d. endoplasmic reticulum
Q:
The major end products of cellular oxidation of carbohydrate include:
a. carbon, nitrogen, and hydrogen.
b. water, carbon dioxide, and energy.
c. glucose and amino acids.
d. dietary fiber and ammonia.
Q:
Glycolysis is a process involving:
a. synthesis of fatty acids.
b. reactions that convert glucose to glycogen.
c. reactions that convert glucose to pyruvate.
d. reactions that convert glycogen to protein.
Q:
Due to a lack of the enzyme glucose-6-phosphatase, which tissue capable of glycogenesis cannot contribute to blood glucose levels between meals?
a. liver
b. muscle
c. brain
d. kidney
Q:
Insulin is an anabolic hormone. Which process does insulin stimulate?
a. lipolysis
b. gluconeogenesis
c. glycogenesis
d. ketogenesis
Q:
People with type 1 diabetes have
a. slow translocation of GLUT4 receptors from the Golgi body.
b. lack of mRNA synthesis for GLUT4 receptors in adipocytes or myocytes.
c. increased glycogenesis in myocytes after a meal.
d. below-normal glucokinase activity because of low insulin levels.
Q:
Glycemic load considers the _____ in the food.
a. protein and carbohydrate content
b. fat and carbohydrate content
c. fat to carbohydrate ratio
d. quantity and quality of carbohydrate
Q:
Which hormonal changes occur in response to a fall in blood glucose concentration?
a. increased insulin, decreased glucagon
b. decreased insulin, increased glucagon
c. decreased insulin, decreased glucocorticoids
d. increased insulin, increased glucagon
Q:
The glucose transporter that is sensitive to insulin is
a. GLUT1.
b. GLUT2.
c. GLUT4.
d. SGLT1.