Deck 23: Carbohydrate Metabolism

Question 1

The normal blood sugar level, for an adult, measured after a fast of 8-12 hours is

A)90-110 mg\100 mL.
B)40-80 mg\100 mL.
C)50-70 mg\100mL.
D)70-110 mg\100mL.

Answer 1

70-110 mg\100mL.

Question 2

Under anaerobic conditions in the body, pyruvate is converted to _____ .

A)ethanol
B)CO₂ & H₂O
C)acetyl CoA
D)lactate

Answer 2

lactate

Question 3

A key organ in regulating blood glucose levels is the _____ .

A)heart
B)liver
C)adrenal cortex
D)thyroid

Answer 3

liver

Question 4

The pain and cramps which accompany physical exhaustion are associated with the accumulation of excess _____ .

A)lactate
B)pyruvate
C)acetyl CoA
D)acetaldehyde

Question 5

A condition in which glucose appears in the urine is called _____ .

A)hypoglycemia
B)hyperglycemia
C)glucosuria
D)galactosemia

Question 6

In the electron transport chain, FADH₂ delivers hydrogen ions and electrons to which of the following?

A)coenzyme Q
B)NAD⁺
C)flavoprotein
D)cytochrome b

Question 7

A blood sugar level that is lower than normal is referred to as _____ .

A)hypoglycemia
B)hyperglycemia
C)glucosuria
D)diabetes mellitus

Question 8

Glycolysis occurs within the _____ .

A)mitochondria
B)nucleus
C)vacuoles
D)cytoplasm

Question 9

The major products of carbohydrate digestion are _____ .

A)monosaccharides
B)monosaccharides & disaccharides
C)acetyl CoA
D)pyruvic acid

Question 10

Which of the following is an allosteric enzyme which serves as a control point in the citric acid cycle?

A)malate dehydrogenase
B)fumarase
C)citrate synthetase
D)succinate dehydrogenase

Question 11

Which of the following is a product of glycolysis?

A)pyruvate
B)CO₂ + H₂O
C)lactate
D)acetyl CoA

Question 12

Each turn of the citric acid cycle produces ____ molecules of CO₂.

A)2
B)3
C)4
D)5

Question 13

The discomfort associate with excess alcohol consumption is due to the buildup of _____ .

A)acetyl CoA
B)acetaldehyde
C)lactate
D)pyruvate

Question 14

Phosphofructokinase, one of the enzymes which regulates the glycolysis pathway, is activated by _____ .

A)glucose
B)citrate
C)ADP
D)ATP

Question 15

Which of the following can be used to fuel the glycolysis pathway?

A)glucose
B)glucose and fructose
C)fructose and galactose
D)glucose, fructose and galactose

Question 16

Glycolysis

A)costs two ATP molecules at the beginning of the process.
B)produces four ATP molecules.
C)has a resultant molecule that enters the next step of the process, the citric acid cycle.
D)More than one response is correct.

Question 17

The direct fuel of the citric acid cycle is _____ .

A)glucose
B)glycogen
C)fatty acids
D)acetyl CoA

Question 18

Under aerobic conditions in the body, pyruvate is converted to _____ .

A)lactate
B)acetyl CoA
C)ethanol
D)acetaldehyde

Question 19

Blood sugar

A)is a term that normally refers to the concentration of glucose and fructose in the blood.
B)should be in the range of 70-90 mg\mL or the renal threshold is exceeded.
C)is regulated by the liver which removes glucose from the blood in response to an increase after a meal.
D)testing can be inferred by the glucosuria test of the perspiration.

Question 20

All pyruvate has a similar fate, in that it eventually produces _____ .

A)CO₂
B)acetyl CoA
C)NAD⁺
D)FAD

Question 21

During gluconeogenesis, pyruvate is formed from glycerol, certain amino acids and _____ .

A)acetyl CoA
B)glucose
C)lactate
D)glycogen

Question 22

What is the final acceptor of electrons during electron transport?

A)NAD⁺
B)NADH
C)FAD
D)O₂

Question 23

Glycogenolysis can be correctly represented by which of the following _____ .

A)glucose → glycogen
B)glycogen → glucose
C)pyruvate → glycogen
D)glycogen → pyruvate

Question 24

Glycogenolysis does not occur in muscle tissue because of the absence of the enzyme _____ .

A)glucose 6-phosphatase
B)glycogen phosphorylase
C)phosphoglucomutase
D)pyruvate kinase

Question 25

Which of the following foods is most likely to cause problems to those individuals that are lactose intolerant?

A)Swiss cheese
B)skim milk
C)cheddar cheese
D)margarine

Question 26

The net yield of ATP molecules from the complete catabolism of one molecule of glucose is _____ .

A)18
B)24
C)32
D)42

Question 27

Lactose intolerance

A)can only be controlled by eliminating dairy products.
B)produces symptoms including bloating and diarrhea.
C)is due to a missing enzyme by approximately 20% of adults in the USA.
D)All of these responses are correct.

Question 28

The bulk of the energy utilized by marathon runners is provided by _____ .

A)blood glucose
B)glycogen
C)protein
D)fatty acids

Question 29

Approximately ____ percent of the energy available in glucose catabolism is trapped in the formation of ATP.

A)20
B)40
C)60
D)80

Question 30

The high-energy compound involved in the conversion of glucose to glycogen is _____ .

A)GTP
B)ATP
C)ADP
D)UTP

Question 31

What ions present in the cytochrome aid in passing electrons along the electron transport chain?

A)Fe²⁺ and Fe³⁺
B)Cu⁺ and Cu²⁺
C)Zn⁺ and Zn²⁺
D)Mg²⁺ and Na⁺

Question 32

Synthesis of glucose from pyruvate during the Cori cycle occurs primarily in the _____ .

A)muscles
B)liver
C)bloodstream
D)heart tissue

Question 33

Glycogen is stored primarily in the liver and the _____ .

A)heart
B)pancreas
C)muscles
D)fat deposits

Question 34

Which of the following hormones acts to lower the blood glucose level?

A)glucagon
B)insulin
C)epinephrine
D)More than one response is correct.

Question 35

If a glucose tolerance test shows an abnormally high level of glucose in the blood after several hours, the person is possibly _____ .

A)hypoglycemic
B)diabetic
C)anemic
D)overweight

Question 36

Which of the following hormones acts to raise the blood glucose level?

A)glucagon
B)insulin
C)epinephrine
D)More than one response is correct.

Question 37

Contrast complete glucose oxidation, lactate fermentation, and alcoholic fermentation.

A)Glucose oxidation produces approximately the same amount of ATP as lactate and alcoholic fermentation together.
B)Lactate fermentation is the most important process of the three for the production of energy in muscles that are performing extended periods of work.
C)Lactate fermentation produces less ATP than does glucose oxidation, but approximately the same amount of ATP as alcoholic fermentation.
D)The complete oxidation of glucose produces fructose; that of lactate fermentation produces lactic acid; and that of alcoholic fermentation produces ethanol.

Question 38

The majority of ATP produced during the catabolism of glucose is formed during _____ .

A)oxidative phosphorylation
B)glycolysis
C)the citric acid cycle
D)the formation of acetyl CoA

Question 39

Insulin causes

A)liver to release glycogen.
B)glucose to enters cells.
C)glucose conversion to fat.
D)HDL production.

Question 40

The main source of energy for the brain is _____ .

A)glucose
B)fatty acids
C)glycogen
D)glycerol

Question 41

Which of the following reactions represents a step in the metabolism of pyruvate that occurs under aerobic conditions?

A)
B)
C)
D)

Question 42

Glucose-6-phosphate is best represented by which of the following?  (Note: the wavy bond indicates that the -OH could either be up or down.)

A)
B)
C)
D)

Question 43

Under anaerobic conditions in humans, what is pyruvate converted to?

A)ethanol
B)lactate
C)CO₂
D)none of these

Question 44

In the diagram of the citric acid cycle shown, what do the two points indicated by an asterisk have in common?

A)CO₂ is produced.
B)NAD⁺ is reduced.
C)ATP is produced.
D)All will occur.

Question 45

Under aerobic conditions in humans, what is pyruvate converted to?

A)ethanol
B)lactate
C)CO₂
D)none of these

Question 46

Consider the diagram of the mitochondrion shown below.  During electron transport, protons (H⁺)are pumped into what area of the mitochondrion?

A)2
B)3
C)4
D)5

Question 47

Control points of the citric acid cycle are shown by the numbers in the following diagram.  Which of the following correctly describes control of the cycle>

A)Point 1 is inhibited by NADH and activated by ADP.
B)Point 2 is inhibited by NADH and activated by ATP.
C)Point 3 is inhibited by both NADH and ADP.
D)All of these.

Question 48

During the first step of the citric acid cycle, citrate is produced from an acetyl group and ____?

A)oxaloacetate
B)malate
C)pyruvate
D)fumerate

Question 49

Which of the following is not an energy source used in metabolism?

A)UTP
B)ATP
C)GTP
D)UTC

Question 50

The free energy change for the complete oxidation of one mole of glucose is -686 kcal and Δ G°' for the hydrolysis of ATP is -7.3 kcal\mol.   How many moles of ATP could be synthesized if the entire oxidation process were 100% efficient in converting this energy to the production of ATP?

A)0.0106  mol ATP
B)94.0 mol ATP
C)5.01 × 10³ mol ATP
D)32.0 mol ATP

Question 51

How many molecules of CO₂ are produced per molecule of glucose as a result of the pyruvate dehydrogenase complex?

A)0
B)1
C)2
D)3

Question 52

Consider the figure below.  What process is depicted?

A)Cori cycle
B)glycolysis
C)fermentation
D)glucogenolysis

Question 53

Low carbohydrate intake during heavy exercise followed by high carbohydrate intake with light exercise is an example of ____ loading.

A)carbohydrate
B)ATP
C)energy
D)glucose

Question 54

Which of the following occurs in the citric acid cycle?

A)oxidation of carbon
B)generation of ATP
C)'pumping' of hydrogen ions
D)more than one answer is correct

Question 55

The process where ADP is converted to ATP while coupled to the electron transport chain is

A)citric acid cycle.
B)alcohol fermentation.
C)oxidative phosphorylation.
D)the Cori cycle.

Question 56

Chemiosmotic hypothesis is the postulate that a(n)____ flow across the inner mitochondrial membrane during operation of the electron transport chain provides energy for ATP production.

A)electron
B)proton
C)neutron
D)electrical

Question 57

The reaction of NAD⁺ to produce NADH is an example of what type of reaction?

A)oxidation
B)reduction
C)hydrolysis
D)hydration

Question 58

Consider the diagram below.  That is the step that is labeled 1 called?

A)fermentation
B)gluconeogenesis
C)glycolysis
D)glycogenolysis

Question 59

Lactate, produced in the muscles, is sent to the liver for processing. This is one step of ____.

A)the citric acid cycle
B)the Cori cycle
C)glycolysis
D)oxidative phosphorylation

Question 60

Each turn of the citric acid cycle produces ____ NADH coenzyme(s).

A)0
B)1
C)2
D)3

Question 61

Epinephrine is a peptide hormone.

Question 62

Glucagon can counteract the effect of insulin.

Question 63

The first step in the processes of glycolysis is a phosphorolation.

Question 64

The function of glycolysis is to extract energy from the glucose molecule.

Question 65

Consider the figure shown below where four different pathways are labeled 1 - 4.  Which of those pathway is a fermentation process?

A)1
B)2
C)3
D)4

Question 66

Insulin is a regulatory enzyme.

Question 67

The citric acid cycle (CAC)is also called the tricarboxylic acid (TCA)cycle and the Krebs cycle.

Question 68

As a molecule of glucose passes through the glycolysis pathway, three molecules of pyruvate are formed.

Question 69

Glycolysis and the TCA are so efficient that over 90% of the chemical energy is stored in the form of ATP for the use of the cell.

Question 70

Glycolysis is a metabolic pathway that is self-regulating.

Question 71

The catabolism of one molecule of glucose in the muscle cells produces 32 ATP molecules.

Question 72

Both glucagon and insulin are produced by the pancreas.

Question 73

All of the members of the citric acid cycle are acids.

Question 74

Insulin decreases the rate of synthesis of glycogen and fatty acids.

Question 75

Epinephrine stimulates glycolysis.

Question 76

The electron transport chain exists for the purpose of removing excess electrons from the cell.

Question 77

Glucose is the only sugar used by the human body.

Question 78

The processes of producing both lactate and ethanol are anaerobic processes.

Question 79

Which of the following is not considered a component of the electron transport chain?

A)cytochrome c (cyt c)
B)coenzyme Q (CoQ)
C)Fe-S protein (Fe-S)
D)adenosine diphosphate (ADP)

Question 80

How can a person avoid an "energy crash" one to three hours after a meal?

A)Consume foods with elevated levels of caffeine.
B)Increase the time between eating meals.
C)Eat meals with a high overall glycemic index.
D)Eat meals with a low overall glycemic index.