Gropper - Carbohydrates Flashcards
The majority of energy in the typical American diet comes from ____.
(A) fat
(B) protein
(C) carbohydrate
(D) vitamins
(C) carbohydrate
A ketopentose is a carbohydrate containing ____.
(A) five carbons and a ketone group
(B) six carbons and an aldehyde group
(C) three carbons and an aldehyde group
(D) seven carbons and a ketone group
(A) five carbons and a ketone group
What type of bond holds two monosaccharides together?
(A) ionic
(B) hydrogen
(C) covalent
(D) peptide
(C) covalent
When compounds with one or more chiral carbon atoms and the same formula are arranged as mirror images they are said to be ____.
(A) symmetrical
(B) enantiomers
(C) rotated
(D) linear
(B) enantiomers
Name the model that depicts cyclized monosaccharides as lying in a horizontal plane with the hydroxyl groups pointing down or up from the plane.
(A) Haworth
(B) Fischer projection
(C) cyclized Fischer projection
(D) stereoisomer
(A) Haworth
What are the major dietary energy sources that are composed of two simple sugars?
(A) disaccharides
(B) polysaccharides
(C) monosaccharides
(D) trioses
(A) disaccharides
What is the most common digestible homopolysaccharide existing as both amylose and amylopectin?
(A) glycogen
(B) cellulose
(C) hemicellulose
(D) starch
(D) starch
Which of the following homopolysaccharides made of glucose contributes the most energy to the ordinary diet?
(A) amylose
(B) amylopectin
(C) glycogen
(D) cellulose
(B) amylopectin
A homopolysaccharide that is important in human diets is ____ and the end product formed from the complete digestion of this homopolysaccharide is ____.
(A) cellulose; glucose
(B) lactose; galactose
(C) glycogen; glucose
(D) starch; glucose
(D) starch; glucose
Which disaccharide is commonly found in mushrooms?
(A) glucose
(B) fructose
(C) trehalose
(D) galactose
(C) trehalose
What is the key enzyme in digestion of polysaccharides?
(A) starch amylopectin
(B) β-amylase
(C) α-dextranase
(D) α-amylase
(D) α-amylase
Cellulose is a polymer of glucose where the monomers are connected by β-linkages. Humans cannot digest this substance because ____.
(A) they only produce α-amylase
(B) they produce insufficient quantities of β-amylase
(C) cellulose is resistant to the human form of β-amylase (D) the β-linkages are too strong to be hydrolyzed
(A) they only produce α-amylase
Chiral carbon atoms have ____.
(A) four hydrogens attached to them
(B) two methyl groups and two hydrogens attached to them
(C) three hydrogen atoms and one methyl group attached to them
(D) four different atoms or groups attached to them
(D) four different atoms or groups attached to them
The enzyme needed to hydrolyze the α (1,6) bond of amylopectin is ____, which is secreted by the ____.
(A) amylase; enterocyte
(B) sucrose; pancreas
(C) lactase; enterocyte
(D) isomaltase; enterocyte
(D) isomaltase; enterocyte
The disaccharidases are synthesized by the ____.
(A) pancreas
(B) liver
(C) enterocyte
(D) chief cell
(C) enterocyte
Sucrose digestion is initiated in the ____.
(A) pylorus
(B) fundus
(C) duodenum
(D) mouth
(C) duodenum
Starches in the duodenum and jejunum are acted upon by ____.
(A) β-amylase
(B) lipase
(C) sucrase
(D) α-amylase
(D) α-amylase
α-dextrinase is also called ____.
(A) β-amylase
(B) isomaltase
(C) α-amylase
(D) lactase
(B) isomaltase
Choose the best description of the main method of glucose absorption.
(A) passive diffusion down a concentration gradient
(B) active transport with fructose
(C) facilitated transport
(D) active transport with sodium
(D) active transport with sodium
Which sugar is not present in the systemic circulation due to efficient removal by the liver?
(A) glucose
(B) fructose
(C) galactose
(D) sucrose
(B) fructose
The glucose transporter that is sensitive to insulin is ____.
(A) GLUT1
(B) GLUT2
(C) GLUT4
(D) SGLT1
(B) GLUT2
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
(B) decreased insulin, increased glucagon
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
(D) quantity and quality of carbohydrate
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
(D) below-normal glucokinase activity because of low insulin levels
Insulin is an anabolic hormone. Which process does insulin stimulate?
(A) lipolysis
(B) gluconeogenesis
(C) glycogenesis
(D) ketogenesis
(C) glycogenesis
Glucose phosphorylation in the liver is catalyzed by ____.
(A) glucokinase
(B) hexokinase
(C) insulin
(D) glucagon
(A) glucokinase
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
(B) muscle
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
(C) reactions that convert glucose to pyruvate
Conversion of phosphorylase b to the active phosphorylase a is carried out by ____.
(A) ADP
(B) AMP
(C) ATP
(D) cAMP
(B) AMP
In what part of the cell does glycolysis occur?
(A) mitochondrion
(B) cytosol
(C) nucleus
(D) endoplasmic reticulum
(B) cytosol
In which cellular site is most of the energy released when carbohydrates are oxidized to carbon dioxide and water?
(A) cytoplast
(B) endothelium
(C) Golgi body
(D) mitochondrion
(D) mitochondrion
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
(B) epinephrine and glucagon
Where are the enzymes that catalyze the citric acid cycle located?
(A) cytoplasmic matrix
(B) endoplasmic reticulum
(C) mitochondrial matrix
(D) lysosome
(C) mitochondrial matrix
In the ____, galactose is eventually converted to ____.
(A) liver; glucose
(B) Kupffer cell; fructose
(C) small intestine; glucose
(D) chylomicron; glucose
(A) liver; glucose
Which substance is converted into glycogen in the process of glycogenesis?
(A) 2-phosphoglycerate
(B) glucose-1-phosphate
(C) fructose-1-phosphate
(D) phosphoglyceraldehyde
(B) glucose-1-phosphate
In the complete oxidation of 1 mol of glucose, how many ATPs are formed?
(A) 4-6
(B) 8-12
(C) 18-24
(D) 30-32
(D) 30-32
The poison, sodium cyanide, inhibits the enzyme cytochrome c oxidase. Why is ingestion of this poison usually fatal?
(A) It blocks the production of ATP in the cells.
(B) It causes cells to rupture.
(C) It changes membrane permeability allowing important molecules to leave the cell.
(D) It causes changes in the acetyl-coenzyme A molecule.
(A) It blocks the production of ATP in the cells.
The conversion of pyruvate to oxaloacetate in gluconeogenesis allows which molecules to enter the gluconeogenic pathway?
(A) alcohols
(B) amino acids
(C) monosaccharides
(D) polysaccharides
(B) amino acids
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
(B) increased
Which process produces glucose-6-phosphate from noncarbohydrate sources?
(A) glycolysis
(B) glycogenolysis
(C) glycogenesis
(D) gluconeogenesis
(D) gluconeogenesis
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
(B) reduced to water
Glucagon, epinephrine, and norepinephrine enhance the regulation of ____.
(A) glucose-1-phosphate
(B) phosphorylase
(C) coenzyme Q
(D) phosphofructokinase
(B) phosphorylase
The occurrence of a molecule in different spatial configurations is ____.
(A) isotopism
(B) isomerism
(C) stereoisomerism
(D) rotationalism
(C) stereoisomerism
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
(D) chemiosmotic
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
(A) pentose phosphates and NADPH
Which tissue has the least activity of the pentose phosphate pathway?
(A) liver
(B) adrenal cortex
(C) mammary gland
(D) skeletal muscle
(D) skeletal muscle
Gluconeogenesis is essentially the reversal of which pathway?
(A) glycogenesis
(B) glycolysis
(C) TCA cycle
(D) glycogenolysis
(B) glycolysis
All of the following are substrates for gluconeogenesis EXCEPT ____.
(A) fatty acids
(B) lactate
(C) glycerol
(D) glucogenic amino acids
(A) fatty acids
Enterocytes absorb only one form of carbohydrate. This form is ____.
(A) disaccharides
(B) polysaccharides
(C) monosaccharides
(D) trisaccharides
(C) monosaccharides
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
(C) fructose-1,6-bisphosphatase
In skeletal muscle, hypercortisolism may lead to ____.
(A) enlargement of muscle fibers
(B) reduction in the size of muscle fibers
(C) increased contractile strength of muscle fibers
(D) increased healing capability
(B) reduction in the size of muscle fibers
The abundance of GLUT4 is increased by induction in response to a high-CHO meal.
(A) True
(B) False
(B) False
The purpose of the pentose phosphate pathway is to generate ribose, for nucleic acid synthesis, and NAD, for oxidizing power.
(A) True
(B) False
(B) False
Pentose sugars provide more dietary energy than hexose sugars.
(A) True
(B) False
(B) False
Glucose is transported from the lumen into the enterocyte by active transport using SGLT1 protein, which also requires Na as a co-transporter.
(A) True
(B) False
(A) True
The process of gluconeogenesis occurs mainly in the liver and, in cases of starvation, in the kidneys as well.
(A) True
(B) False
(A) True
The 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.
(A) True
(B) False
(B) False
Glycogenolysis in muscle cells provides glucose that can be transported through the bloodstream.
(A) True
(B) False
(B) False
Glucose phosphorylation in the liver is catalyzed by glucokinase.
(A) True
(B) False
(A) True
The Cori cycle would be active under anaerobic conditions, such as excessive muscle exertion.
(A) True
(B) False
(A) True
Maintenance of normal blood glucose concentration is controlled by the small intestine, the liver, the kidneys, skeletal muscle, and adipose tissue.
(A) True
(B) False
(A) True
Because 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.
(A) True
(B) False
(B) False
All cells have mitochondria, which act as the main site for ATP production.
(A) True
(B) False
(B) False
Active transport requires energy for the Na-K pump to transport Na out of the cell, thereby driving the transport of another substance (e.g., glucose) when the Na re-enters the cell down its concentration gradient.
(A) True
(B) False
(A) True
Fructose transport into the enterocyte relies on the facilitative transporter GLUT5.
(A) True
(B) False
(A) True
After hydrolysis of triacylglycerols stored in adipose tissue, free glycerol in the blood is converted in the liver to glucose via glycogenolysis.
(A) True
(B) False
(B) False
According to the USDA data for the years 1970-2010, which food source is the most abundant macronutrient (by weight) in the American diet?
(A) carbohydrates
(B) fats
(C) proteins
(D) nucleic acids
(A) carbohydrates
According to the USDA data for the year 2010, most of the carbohydrates in the American diet came from ____.
(A) disaccharides
(B) monosaccharides
(C) grain products
(D) soft drinks
(C) grain products
In order to be absorbed by the body, all digestible carbohydrates must be broken down into ____.
(A) disaccharides
(B) monosaccharides
(C) trisaccharides
(D) oligosaccharides
(B) monosaccharides
Upon digestion, food carbohydrates yield four times more glucose than ____.
(A) fructose
(B) galactose
(C) sucrose
(D) trehalose
(A) fructose
The second most abundant food sources of carbohydrates are ____.
(A) complex carbohydrates
(B) sugars and sweeteners
(C) fruits and vegetables
(D) digested proteins
(B) sugars and sweeteners
