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Biochemisty Main > 4th Biochemistry Lecture Exam (Batch 2024) > Flashcards

4th Biochemistry Lecture Exam (Batch 2024) Flashcards

1
Q
  1. TRUE about pyruvate dehydrogenase.
    A. Oxidatively decarboxylates pyruvate into Acetyl-CoA.
    B. Phosphorylates pyruvate into Acetyl-CoA.
    C. Dehydrates pyruvate into Acetyl-CoA.
    D. Deaminates pyruvate into Acetyl-CoA.
A

A. Oxidatively decarboxylates pyruvate into Acetyl-CoA.

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2
Q
  1. Areas of regulation in the glycolytic pathway EXCEPT.
    A. Phosphofructokinase
    B. Hexokinase
    C. Aldolase
    D. Pyruvate kinase
A

C. Aldolase

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3
Q
  1. What molecule is regenerated at the end of the citric acid cycle for gluconeogenesis?
    A. Ketoglutarate
    B. Citrate
    C. Malate
    D. Oxaloacetate
A

D. Oxaloacetate

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4
Q
  1. The reaction involving glucose-6-phosphate, catalysed by phosphohexose isomerase, produces the compound;
    A. Fructose-6-phosphate
    B. Fructose-1,6-biphosphate
    C. Dihydroxyacetone phosphate
    D. 1,3-biphosphoglycerate
A

A. Fructose-6-phosphate

Step 2

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5
Q
  1. What is an important compound at the junction of glycolysis, gluconeogenesis, and the pentose phosphate pathway?
    A. Glyceraldehyde-3-phosphate
    B. 1,3-biphosphoglycerate
    C. Glucose-6-phosphate.
    D. Fructose-6-phosphate
A

C. Glucose-6-phosphate.

Step 1 : G6P -> 6-phosphogluconolactone (6PGL)
Enzyme: Glucose 6 phosphate Dehydrogenase (G6PDH)

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6
Q
  1. Glycolysis in erythrocytes always terminates in this substrate.
    A. Lactate
    B. Pyruvate
    C. Glucose
    D. Acetyl-CoA
A

A. Lactate

Aerobic:
* G + 2 Pi + 2 ADP2 lactate + 2 ATP + 2 H2O;
* net of 2 ATP / G; At oxygen debt or lacking mitochondria, no net NADH+H consumption

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7
Q
  1. What comprises pyruvate dehydrogenase enzyme complex?
    A. Thiamine diphosphate, CoA-SH, Riboflavin
    B. Thiamine diphosphate, Lipoate, Riboflavin
    C. Thiamine diphosphate, CoA-SH, Lipoate
    D. Thiamine diphosphate, CoA-SH, CO2
A

B. Thiamine diphosphate, Lipoate, Riboflavin

E1: Pyruvate Dehydrogenase
Co-Enzyme : Thiamine Pyrophosphate (TPP)

E2: Dihydrolipoyl Transacetylase
Co-Enzyme : Lipoate, Coeynzyme A (Vitamin B5 : Pantothenic Acid)

E3: Dihydrolipoyl Dehydrogenase
Co-enzyme: NADH (Vitamin B3 : Niacin), FADH (Vitamin B2: Riboflavin)

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8
Q
  1. What inhibits pyruvate dehydrogenase?
    A. Pyruvate
    B. FADH
    C. Acetyl-CoA.
    D. Glucose
A

C. Acetyl-CoA.

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9
Q
  1. In glycolysis, how much ATP is produced via substrate level phosphorylation?
    A. 4
    B. 5
    C. 6
    D. 7
A

A. 4

Substate-level phosphorylation = 4 ATP
(7) Phosphoglycerate kinase (1,3-BPG -> 3-PG)
(10) Pyruvate Kinase (PEP->Pyruvate)

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10
Q
  1. How much energy is produced from the reduction of pyruvate to Acetyl-CoA?
    A. 3 FADH
    B. 2 NADH
    C. 5 GTP
    D. 4 ATP
A

B. 2 NADH

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11
Q
  1. What is the important substrate regenerated in the reaction catalysed by lactate dehydrogenase for the continuation of anaerobic glycolysis?
    A. NADH
    B. NAD+
    C. Lactate
    D. Pyruvate
A

B. NAD+

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12
Q
  1. Which catalyzes an irreversible reaction?
    A. Phosphohexose isomerase
    B. Pyruvate kinase
    C. Aldolase
    D. Enolase
A

B. Pyruvate kinase

Regulatory/ Irreversible Steps
(1) Hexokinase/ Glucokinase
(3) Phosphofructokinase-1 (Rate-limiting step)
(10) Pyruvate Kinase

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13
Q
  1. Which enzyme commits the glucose molecule to the cell and prevents it from leaving the cell’s plasma compartment?
    A. Glycogen synthase
    B. Glycogen phosphorylase
    C. Glucose-6-phosphate
    D. Phosphofructokinase
A

D. Phosphofructokinase

Regulatory/ Irreversible Steps
(1) Hexokinase/ Glucokinase
(3) Phosphofructokinase-1 (Rate-limiting step)
(10) Pyruvate Kinase

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14
Q
  1. Which enzyme is active when phosphorylated?
    A. Glycogen synthase
    B. Glycogen phosphorylase
    C. Glucose-6-phosphate
    D. Phosphofructokinase
A

B. Glycogen phosphorylase

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15
Q
  1. What is the rate limiting factor of glycolysis?
    A. Glucose-6-phosphate
    B. Phosphofructokinase-1
    C. Pyruvate kinase
    D. All of the above
A

B. Phosphofructokinase-1

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16
Q
  1. Which of the following reactions are considered as gluconeogenic reactions or pathways?
    A. Glycogen → Glucose
    B. Alanine → Pyruvate
    C. Acetoacetate → Glucose
    D. Pyruvate → Acetyl-CoA
A

B. Alanine → Pyruvate

Glycogen ➝ Glucose (Glycogenesis)
Alanine ➝ Pyruvate (GNG : Glucose-Alanine Cycle)
Acetoacetate ➝Glucose (Cholesterol synthesis)
Pyruvate ➝ Acetyl-CoA (Transition State)

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17
Q
  1. Which of the following is not a gluconeogenic enzyme?
    A. Glucose-6-phosphatase
    B. Glyceraldehyde-3-phosphate dehydrogenase
    C. Phosphoglycerate kinase
    D. Pyruvate kinase
A

D. Pyruvate kinase

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18
Q
  1. What is the role of the enzyme aldolase in gluconeogenesis?
    A. It synthesizes 2 triose phosphates for gluconeogenesis
    B. It condenses 2 triose phosphates to form a 6-carbon compound
    C. It converts aldoses to ketoses
    D. It delivers adenosine triphosphate to the cytosol as a source of energy for gluconeogenesis
A

B. It condenses 2 triose phosphates to form a 6-carbon compound

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19
Q
  1. Why is gluconeogenesis not possible in skeletal muscles?
    A. Skeletal muscles do not have the enzyme lactate dehydrogenase to convert lactate to pyruvate
    B. Skeletal muscles do not have mitochondria for oxaloacetate synthesis
    C. Skeletal muscles do not have the enzyme glucose-6-phosphatase
    D. Skeletal muscles are deficient in fructose-1,6-bisphosphatase, the rate-limiting enzyme of
    Gluconeogenesis
A

C. Skeletal muscles do not have the enzyme glucose-6-phosphatase

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20
Q
  1. Which of the following can be used as a substrate for gluconeogenesis?
    A. Acetyl-CoA
    B. Lactate
    C. Acetoacetate
    D. Leucine
A

B. Lactate

GNG:
Synthesis of glucose from non-carb sources
* Lactate
* Pyruvate
* Glycerol
* Glucogenic AA (Alanine)
* Odd-chain FA (Propionate)

FUNCTION OF GNG
* maintains blood sugar concentration,
* uses lactate and glycerol (end products of glycolysis and glycerol),
* excretes excess protons by kidneys during metabolic acidosis,
* recycles C skeletons of deaminated AA

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21
Q
  1. Which glucose transporter is activated in the presence of insulin?
    A. GLUT 1
    B. GLUT 2
    C. GLUT 4
    D. SGLT 1
A

C. GLUT 4

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22
Q
  1. Which is the correct sequence of events for the secretion of insulin from the pancreas?
    A. Increase glucose → increase glycolysis → increased ATP synthesis → depolarization of the beta cell → exocytosis of insulin.
    B. Decreased serum glucose → increased pancreatic gluconeogenesis → increased glycolysis →
    depolarization of the beta cell → insulin secretion
    C. Increased glycolysis → elevation of pancreatic glucose → increased ATP synthesis → increased free
    phosphate in pancreas → insulin exocytosis
    D. Decrease of pancreatic glucose → cell depolarization → increased calcium influx to the cell → increased
    glycolysis → insulin secretion
A

A. Increase glucose → increase glycolysis → increased ATP synthesis → depolarization of the beta cell → exocytosis of insulin.

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23
Q
  1. Which enzymes circumvent the glycolytic reaction catalysed by pyruvate kinase?
    A. Pyruvate dehydrogenase and lactate dehydrogenase
    B. Pyruvate carboxylase and PEP carboxykinase
    C. Hexokinase and glucokinase
    D. Fructose-6-phosphate and fructose-1,6-bisphosphate
A

B. Pyruvate carboxylase and PEP carboxykinase

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24
Q
  1. Which of the following substrates are decreased by glucagon?
    A. Glucose
    B. Fructose-2,6-bisphosphate
    C. Fructose
    D. Cyclic AMP
A

B. Fructose-2,6-bisphosphate

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25
Q
  1. Which portion of an amino acid is used for gluconeogenesis?

A. Carbon skeleton
B. Amino group
C. Carboxyl group
D. Peptide linkage

A

A. Carbon skeleton

FUNCTION OF GNG
* maintains blood sugar concentration,
* uses lactate and glycerol (end products of glycolysis and glycerol),
* excretes excess protons by kidneys during metabolic acidosis,
* recycles C skeletons of deaminated AA

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26
Q
  1. During starvation, which molecule acts as an activator of gluconeogenesis?
    A. Acetyl-CoA
    B. Lactate
    C. ATP
    D. NADH
A

A. Acetyl-CoA

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27
Q
  1. Which hormone is the primary regulator of gluconeogenesis?
    A. Epinephrine
    B. Glucagon
    C. Insulin
    D. Incretin
A

B. Glucagon

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28
Q
  1. Which of the following is required by the enzyme PEP carboxykinase?
    A. Biotin
    B. GTP.
    C. Pyridoxal phosphate
    D. NADH
A

B. GTP.

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29
Q
  1. How many DHAPs are needed to synthesize 1 molecule of glucose?
    A. 1
    B. 2
    C. 3
    D. None of the above
A

A. 1

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30
Q
  1. Which fatty acid can synthesize glucose?
    A. Acetate
    B. Malate
    C. Propionate
    D. Palmitate
A

C. Propionate

Gluconeogenesis:
Glucogenic AA (Alanine) : Glucose Alanine Cycle
Lactic Acid (RBC) : Cori cycle
Glycerol (Propionate): Lipolysis

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31
Q
  1. Secretion of insulin from pancreatic B cells;
    A. Glycolysis
    B. Gluconeogenesis
A

A. Glycolysis

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32
Q
  1. Increased fructose-2,6-bisphosphate concentration;
    A. Glycolysis
    B. Gluconeogenesis
A

A. Glycolysis

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33
Q
  1. Increased cyclic AMP synthesis;
    A. Glycolysis
    B. Gluconeogenesis
A

B. Gluconeogenesis

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34
Q
  1. Increased beta oxidation of fatty acids;
    A. Glycolysis
    B. Gluconeogenesis
A

B. Gluconeogenesis

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35
Q
  1. Increased catecholamine synthesis
    A. Glycolysis
    B. Gluconeogenesis
A

B. Gluconeogenesis

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36
Q
  1. What happens during glycolysis?
    A. Glucose is converted to one molecule of pyruvate
    B. NADH is produced
    C. Multiple oxidations give the energy the pathway is known for
    D. ADP is required to start the process
A

B. NADH is produced

Glucose (6C) -> 2 Pyruvate (3C)
Step 6 (NAD+ -> NADH)
Investment/Priming Stage (ATP -> ADP) : Step 1 & 3

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37
Q
  1. Which of the statements below about glucose is NOT true?
    A. It is catabolized in gluconeogenesis
    B. It travels easily in the blood
    C. It is stored in polymers in the body
    D. It is made from simple precursors
A

A. It is catabolized in gluconeogenesis

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38
Q
  1. Which of the following is NOT a function of glycolysis?
    A. Fatty acid synthesis
    B. Production of NADPH
    C. ATP synthesis
    D. Provision of building blocks for amino acid synthesis
A

D. Provision of building blocks for amino acid synthesis

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39
Q
  1. Which enzyme has a high Km for glucose and is not subjected to feedback inhibition by glucose-6-phosphate?
    A. Glucose-6-phosphatase
    B. Glycogen phosphorylase
    C. Hexokinase
    D. Glucokinase
A

D. Glucokinase

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40
Q
  1. Which of the following is true of the final product of aerobic glycolysis?
    A. It is a carboxylic acid
    B. It is a 4-carbon sugar
    C. It cannot be used as a substrate for further ATP synthesis
    D. All of the above
A

A. It is a carboxylic acid

Pyruvate = Pyruvic Acid

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41
Q
  1. What is the difference between hexokinase and glucokinase?

A. Hexokinase phosphorylated glucose glucokinase does not
B. Hexokinase is absent in the liver; glucokinase is abundant in the liver
C. Hexokinase is inhibited by glucose-6-phosphate; glucokinase is not
D. Hexokinase has a low affinity for glucose; glucokinase has a high affinity for glucose

A

C. Hexokinase is inhibited by glucose-6-phosphate; glucokinase is not

42
Q
  1. What is the main purpose of the hexokinase reaction?

A. To facilitate the exocytosis glucose from the interior of the cell
B. To activate glucose for glycolysis
C. To convert glucose to a 6-carbon ketose
D. A and B only

A

B. To activate glucose for glycolysis

43
Q
  1. Where does glycolysis take place?

A. Mitochondrial matrix
B. Inner membrane of the mitochondria
C. Outer membrane of the mitochondria
D. Cytoplasm

A

D. Cytoplasm

44
Q
  1. Why is lactate the final product of glycolysis in red blood cells?

A. RBCs have an abundance of lactate dehydrogenase
B. RBCs are not capable of fermentation
C. RBCs lack mitochondria for aerobic glycolysis
D. RBCs are used for gluconeogenesis

A

C. RBCs lack mitochondria for aerobic glycolysis

45
Q
  1. Which of the following inhibits the rate limiting step in glycolysis?

A. Citrate
B. ATP
C. Glucagon
D. All of the above

A

D. All of the above

46
Q
  1. Fill up the missing intermediate in the glycolytic pathway.
    Fructose-1,6-bisphosphate➝

_______________ ➝ Glyceraldehyde-3-phosphate

A. Phosphoenolpyruvate
B. 2-phosphoglycerate
C. 1,3-bisphosphoglycerate
D. Dihdroxyacetone phosphate

A

D. Dihdroxyacetone phosphate

47
Q
  1. Glycolytic pathway regulation involves:

A. Allosteric stimulation by ADP
B. Allosteric inhibition by ATP
C. Feedback, or product inhibition by ATP
D. All of the above

A

D. all of the above

48
Q
  1. Which one of the following statements about PEP (phosphoenolpyruvate) synthesis is correct?

A. Pyruvate can be converted to PEP by pyruvate kinase.
B. Pyruvate can be converted to PEP by a mutase
C. Pyruvate can be converted to PEP by a combination of reactions that use energy from two different types of nucleotide triphosphate
D. Pyruvate is converted to PEP by the citric acid cycle

A

D. Pyruvate is converted to PEP by the citric acid cycle

GNG
Lactate -> Pyruvate -> OAA -> Malate -> OAA ->PEP

49
Q
  1. Which of the following are true about oxaloacetate?

A. It is an intermediary in glycolysis
B. It is an intermediary in the synthesis of glucose from lactate
C. It can cross mitochondrial membranes
D. It is an intermediary in the synthesis of glucose from glycerol

A

A. It is an intermediary in glycolysis

50
Q
  1. Why does the glycolytic pathway continue in the direction of glucose catabolism?

A. There are essentially three irreversible reactions that act as the driving force for the pathway
B. High levels of ATP keep the pathway going in a forward direction
C. The enzymes of glycolytic only function in one direction
D. Glycolysis occurs in either direction

A

A. There are essentially three irreversible reactions that act as the driving force for the pathway

51
Q
  1. The products of the Pentose Phosphate Pathway are;

A. 2 NADPH, 1 CO2, 2 ribose
B. 2 NADPH, 1 CO2, ribose
C. 2 NADPH, 2 CO2, ribose
D. 1 NADPH, 2 CO2, 2 ribose

A

B. 2 NADPH, 1 CO2, ribose

52
Q
  1. Biosynthesis of fatty acids occur in the:
    A. Mammary glands
    B. Ovaries
    C. Adrenals
    D. Liver
A

D. Liver

53
Q
  1. Uses of NADPH include:
    A. Degradation of nitric oxide
    B. Oxidation of hydrogen peroxide
    C. Phagocytosis of RBCs
    D. Reductive biosynthesis
A

D. Reductive biosynthesis

54
Q
  1. A breast fed infant began to vomit frequently and lose weight. Several days later, she developed jaundice, hepatomegaly and bilateral cataract. What is the possible cause for these symptoms?
    A. G6PD deficiency
    B. Galactosemia
    C. Von Gierke’s syndrome
    D. Hereditary Fructose Intolerance
A

B. Galactosemia

55
Q
  1. The uronic acid pathway;
    A. Catalyzes conversion of glucose to glucoronic, pentoses, sialic acid
    B. Energy producing reaction
    C. Occurs in the cytosol
    D. Alternative pathway for the oxidation of glucose
A

D. Alternative pathway for the oxidation of glucose

56
Q
  1. The rate limiting step in glycolysis catalysed by this enzyme is bypassed in the metabolism of fructose.
    A. Phosphofructokinase-1
    B. Glucose-6-phosphate
    C. Glucose-1-phosphate
    D. Glucokinase
A

A. Phosphofructokinase-1

Regulatory/ Irreversible Steps
(1) Hexokinase/ Glucokinase
(3) Phosphofructokinase-1 (Rate-limiting step)
(10) Pyruvate Kinase

57
Q
  1. Hexokinase has a low affinity for;
    A. Fructose-6-phosphate
    B. Fructose-1-phosphate
    C. Fructose
    D. Sucrose
A

C. Fructose

58
Q
  1. Fructose-1-phosphate to glyceraldehyde reaction is catalysed by
    A. Aldolase A
    B. Aldolase B
    C. Aldolase C
    D. All of the above
A

B. Aldolase B

59
Q
  1. Hereditary fructose intolerance is caused by a deficiency in this enzyme
    A. Aldolase A
    B. Aldolase B
    C. Aldolase C
    D. All of the above
A

B. Aldolase B

60
Q
  1. Classic galactosemia is caused by this enzyme deficiency
    A. GALT
    B. Galactokinase
    C. Galactomutase
    D. Phosphogalactogen
A

A. GALT

61
Q
  1. Fructose-6-phosphate can be produced from
    A. Mannose-6-phosphate
    B. Sedoheptulase-6-phosphate
    C. Xylulose-7-phosphate
    D. All of the above
A

A. Mannose-6-phosphate

Hexoses
(Glucose, Galactose, Mannose) : Aldoses
(Fructose) : Ketoses

62
Q
  1. Familial fructokinase deficiency causes no symptoms because:
    A. Hexokinase can phosphorylate fructose
    B. Liver aldolase can metabolize it
    C. Excess fructose is excreted through feces
    D. Excess fructose is converted to glucose
A

A. Hexokinase can phosphorylate fructose

63
Q
  1. A medical student developed haemolytic anemia after taking the oxidizing malarial drug primaquine. This severe reaction is most likely due to:

A. Glucose-6-phosphate dehydrogenase deficiency
B. Scurvy
C. Diabetes
D. Glycogen phosphorylase activity

A

A. Glucose-6-phosphate dehydrogenase deficiency

64
Q
  1. G6PD is most severe in RBCs because:

A. The pentose phosphate pathway is the sole source of NADPH in RBCs
B. The RBCs have nucleus and can produce ribulose-5-phosphate
C. More NADPH is needed in RBCs to reduce glutathione
D. Glucose-6-phosphate is consumed in RBCs

A

A. The pentose phosphate pathway is the sole source of NADPH in RBCs

65
Q
  1. True about G6PD:

A. Characterized by haemolytic anemia
B. Does not affect life expectancy
C. Common in Middle America, Europe and Africa
D. Symptomatic

A

A. Characterized by haemolytic anemia

66
Q
  1. Substances that may make people with G6PD symptomatic

A. Fava beans
B. Anti-tuberculosis drugs
C. Anti-inflammatories
D. All of the above

A

A. Fava beans

67
Q
  1. True of fructose metabolism
    A. Sucrose yields 2 fructose and 1 glucose
    B. Insulin dependent
    C. Bypasses phosphofructokinase-1
    D. All of the above
A

C. Bypasses phosphofructokinase-1

68
Q
  1. Ribulose-5-phosphate is an important product of pentose phosphate pathway because:
    A. It is a substrate for fatty acid synthesis
    B. Is is a substrate for steroids synthesis
    C. It is a substrate for nucleotide synthesis
    D. All of the above
A

D. All of the above

69
Q
  1. Coenzyme responsible for the dehydrogenation of glucose-6-phosphate

A. NADP+
B. NADPH
C. NADP+ and NADPH
D. NAD

A

A. NADP+

PPP
* G6P -> 6-phosphogluconolactone
* Enzyme: G6P DH
* Co-factor: NADP+ -> NADPH

70
Q
  1. True of the pentose phosphate pathway

A. Occurs in the cytoplasm
B. Has three irreversible reactions
C. Produces ATP
D. Produces ribose

A

D. Produces ribose

71
Q
  1. All of the following statements about the pentose phosphate pathway are true EXCEPT

A. Its two functions are to produce NADPH and ribose-5-P
B. It uses glucose-6-phsohate as a substrate when producing NADPH and CO2
C. It is found in the mitochondria of liver, muscle and brain but is absent from most other tissues of the body
D. Glucose-6-phosphate dehydrogenase is the control enzyme and it is regulated by the NADPH concentration of the cell

A

C. It is found in the mitochondria of liver, muscle and brain but is absent from most other tissues of the body

72
Q
  1. NADPH is used by most cells as:

A. A substrate for the electron transport chain
B. To produce ribose-5-P from glyceraldehyde-3-P and fructose-6-Pa reducing agent in detoxification reactions
C. A substrate for transketolase reactions

A

B. To produce ribose-5-P from glyceraldehyde-3-P and fructose-6-Pa reducing agent in detoxification
reactions

73
Q
  1. NADPH is used as a substrate for all of the following EXCEPT
    A. Malate dehydrogenase
    B. Glutathione reductase
    C. Fatty acid synthesis
    D. Deoxynucleotide synthesis
A

A. Malate dehydrogenase

74
Q
  1. The key regulatory enzyme of HMP pathway is:
    A. Glucose-6-phosphate dehydrogenase
    B. Transaldolase
    C. Transketolase
    D. Phosphopentose epimerase
A

A. Glucose-6-phosphate dehydrogenase

75
Q
  1. You have a patient that has haemolytic anemia as a result of eating fava beans. She would have a deficiency of the enzyme _____ and would not be able to synthesize enough _____.
    A. G6P dehydrogenase; ribose-5-P and ribulose-5-P
    B. G6P dehydrogenase; oxidized glutathione and HOOH
    C. G6P dehydrogenase; NADPH
    D. 6-phosphogluconate dehydrogenase; reduced glutathione + HOOH
A

C. G6P dehydrogenase; NADPH

76
Q
  1. What are the main storage forms of fatty acids?

A. Monoacylglycerols (Monoacylglycerides)
B. Diacylglycerols (Diglycerides)
C. Triacylglycerols (Triglycerides)
D. All of the above

A

C. Triacylglycerols (Triglycerides)

77
Q
  1. In our diet, 90% of the fats are in this form;

A. Triglycerides
B. Cholesterol
C. Phospholipids
D. Glycolipids

A

A. Triglycerides

78
Q
  1. These fatty acids lower both the plasma LDL and HDL.

A. ω-6 fatty acids
B. ω-3 fatty acids
C. Saturated fatty acids
D. Monounsaturated fatty acids

A

A. ω-6 fatty acids

79
Q
  1. Which statement more appropriately defines lipids?

A. Lipids are homogenous group of compounds
B. Lipids are essential components of all living organisms
C. Lipids are water soluble organic compounds
D. Lipids are all hydrophobic compounds

A

B. Lipids are essential components of all living organisms

80
Q
  1. The essential fatty acids are examples of this class of fatty acids:

A. Saturated fats
B. Monounsaturated fats
C. Polyunsaturated fats
D. None of the above

A

C. Polyunsaturated fats

81
Q
  1. Which of the following statements is FALSE?

A. As number of double bonds increases, melting point decreases
B. When double bonds are present they are nearly always in the trans configuration
C. When double bonds are present they are always spaced at three-carbon intervals
D. The introduction of a cis double bond causes the fatty acid to bend at that position

A

B. When double bonds are present they are nearly always in the trans configuration

82
Q
  1. With only a few exceptions, natural fatty acids:

A. Contain an even number of carbon atoms
B. Arranged in a branched line
C. Have a carboxyl group (-COOH) at one end
D. Have a methyl group (CH3) at the other end

A

B. Arranged in a branched line

83
Q
  1. The following statements about fatty acids are true EXCEPT;

A. As number of carbon chain length increases, melting point increases
B. When double bonds are present, they are always spaced at 3-carbon intervals
C. When double bonds are present, they are nearly always in the cis rather than a trans configuration
D. The omega system of naming fatty acids involves numbering the carbon atoms beginning at the carboxyl

A

D. The omega system of naming fatty acids involves numbering the carbon atoms beginning at the carboxyl

84
Q
  1. The figure below is a representation of linoleic acid which has the following abbreviations EXCEPT:
    A. 18:2 (9, 12)
    B. 18:2 (6, 9)
    C. 18:2 (ω-6)
    D. 18:2 (n-6)
A

B. 18:2 (6, 9)

85
Q
  1. True of geometric isomerism among fatty acids:
    A. Occurs in saturated fatty acids
    B. Depends on the orientation of the groups around the axes of the double bonds
    C. Trans configuration entails acyl chains to be on same side of the double bonds
    D. Cis configuration entails acyl chains to be on opposite side of the double bonds
A

B. Depends on the orientation of the groups around the axes of the double bonds

86
Q
  1. Which is a TRUE statement about lipids?
    A. Their fluidity decreases with chain length and increases according to degree of unsaturation
    B. Melting point decreases with increasing carbon number
    C. Melting point of a saturated fatty acid is lower than in unsaturated fatty acid with the same number of
    carbons
    D. Double bonds increase melting point relative to saturated acid
A

A. Their fluidity decreases with chain length and increases according to degree of unsaturation

87
Q
  1. Which of the following DOES NOT hold true for trans fatty acids?
    A. They are chemically classified as unsaturated fatty acids
    B. They behave more like a saturated fatty acid in the body
    C. They elevate serum LDL and HDL
    D. They increase the risk for coronary heart disease
A

C. They elevate serum LDL and HDL

88
Q
  1. Which of the following is not involved in naming fatty acids?
    A. Carbon atoms are numbered from the carboxyl carbon
    B. The carboxyl carbon is designated as carbon 1
    C. Carbon number 1 is also known as the α-carbon
    D. The terminal methyl carbon is known as the ω- or n-carbon
A

A. Carbon atoms are numbered from the carboxyl carbon

89
Q
  1. Which statement is not a characteristic of the international union of pure and applied chemistry (IUPAC) nomenclature or “systematic names”, except:

A. Counting begins from the carboxylic acid end
B. Double bonds are labelled with cis-/trans- notation
C. Systematic names give the least information
D. The systematic name tells the number of C in the fatty acid chain, the degree of unsaturation, the C=C bond placement in the molecule and its stereochemistry

A

C. Systematic names give the least information

90
Q
  1. Generation of free radicals from lipids containing polyunsaturated fatty acids, that damage tissues and cause disease results from this process:

A. Peroxidation
B. Oxidation
C. Hydrogenation
D. Carboxylation

A

A. Peroxidation

91
Q
  1. True of essential fatty acids

A. Linoleic acid is the precursor of ω-6 arachidonic acid
B. α-linoleic acid is the precursor of ω-3 fatty acids that are important for growth and development
C. They are dietary essentials in humans because we lack the enzymes needed to synthesize them
D. All of the above

A

D. All of the above

92
Q
  1. The fatty acid abbreviation 18:1 (9) represents the following, EXCEPT

A. The fatty acid has 18 carbons
B. The fatty acid has 1 double bond
C. Position of the double bond is at carbon 9 from the methyl end
D. This represents oleic acid

A

C. Position of the double bond is at carbon 9 from the methyl end

93
Q
  1. These fatty acids are being used to fortify milk formula to promote brain development

A. ω-3 Fatty acids
B. ω-6 Fatty acids
C. ω-7 Fatty acids
D. ω-9 Fatty acids

A

A. ω-3 Fatty acids

94
Q
  1. Palmitic acid, a 16-carbon fatty acid, that functions as structural lipids

A. Short chain fatty acids (SCFA)
B. Medium chain fatty acids (MCFA)
C. Long chain fatty acids (LCFA)
D. Very long chain fatty acids (VLCFA)

A

C. Long chain fatty acids (LCFA)

SCFA: less than 6
MCFA: 6-12
LCFA: 13-21
VLCFA: more than 22

As number of chain length increases, melting point also increases

95
Q
  1. Arachidonic acid is a 20-carbon fatty acid that serves as a precursor of prostaglandins:

A. Short chain fatty acids (SCFA)
B. Medium chain fatty acids (MCFA)
C. Long chain fatty acids (LCFA)
D. Very long chain fatty acids (VLCFA)

A

C. Long chain fatty acids (LCFA)

SCFA: less than 6
MCFA: 6-12
LCFA: 13-21
VLCFA: more than 22

As number of chain length increases, melting point also increases

96
Q
  1. Linoleic acid and α-linoleic acid are essential fatty acids that have 18 carbons

A. Short chain fatty acids (SCFA)
B. Medium chain fatty acids (MCFA)
C. Long chain fatty acids (LCFA)
D. Very long chain fatty acids (VLCFA)

A

C. Long chain fatty acids (LCFA)

SCFA: less than 6
MCFA: 6-12
LCFA: 13-21
VLCFA: more than 22

As number of chain length increases, melting point also increases

97
Q
  1. Capric acid is a 10-carbon fatty acid which is found in significant quantities in milk

A. Short chain fatty acids (SCFA)
B. Medium chain fatty acids (MCFA)
C. Long chain fatty acids (LCFA)
D. Very long chain fatty acids (VLCFA)

A

B. Medium chain fatty acids (MCFA)

SCFA: less than 6
MCFA: 6-12
LCFA: 13-21
VLCFA: more than 22

As number of chain length increases, melting point also increases

98
Q
  1. Acetic acid, a 2-carbon atom fatty acid, is a major end product of carbohydrate fermentation by rumen organisms

A. Short chain fatty acids (SCFA)
B. Medium chain fatty acids (MCFA)
C. Long chain fatty acids (LCFA)
D. Very long chain fatty acids (VLCFA)

A

A. Short chain fatty acids (SCFA)

SCFA: less than 6
MCFA: 6-12
LCFA: 13-21
VLCFA: more than 22

As number of chain length increases, melting point also increases

99
Q
  1. For numbers 99-100, refer to the figure below:
    A. Monoenoic acid
    B. Dienoic acid
    C. Trienoic acid
    D. Tetraenoic acid
    E. Pentaenoic acid
A

B. Dienoic acid

100
Q
  1. The classification of the fatty acid above according to its chain length
    A. Short chain fatty acids (SCFA)
    B. Medium chain fatty acids (MCFA)
    C. Long chain fatty acids (LCFA)
    D. Very long chain fatty acids (VLCFA)
A

C. Long chain fatty acids (LCFA)

SCFA: less than 6
MCFA: 6-12
LCFA: 13-21
VLCFA: more than 22

As number of chain length increases, melting point also increases

Biochemisty Main (29 decks)

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