1st Biochemistry Lecture Exam (Batch 2026) Flashcards by

1.The pH of the body fluids is stabilized by buffer systems. Which of the following compounds is the most effective buffer system at physiological pH ?
A. H2CO3/HCO3- buffer system
B. H2PO4-/HPO42- buffer system
C. Protein buffer
D. buffer activity of Hgb

A. H2CO3/HCO3- buffer system

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2.Which of the laboratory results given shows compensated metabolic alkalosis?
A. Low p CO2, normal bicarbonate and, high pH
B. Low p CO2, low bicarbonate, low pH
C. High p CO2, normal bicarbonate and, low p H
D. High pCO2, high bicarbonate and High pH

D. High pCO2, high bicarbonate and High pH

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3.Which of the following is most appropriate for a female suffering from Type I DM with a pH of 7.2, HCO3- = 17 mmol/L and pCO2 = 20 mm Hg?
A. Metabolic Acidosis
B. Metabolic Alkalosis
C. Respiratory Acidosis
D. Respiratory Alkalosis

A. Metabolic Acidosis

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4.In which acid-base status alteration is the renal glutaminase activity?
A. Metabolic acidosis
B. Respiratory alkalosis
C. Metabolic alkalosis
D. Normal acid-base status

A. Metabolic acidosis

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5.Which of the clinical entities is NOT associated with development of lactic acidosis?
A. Acute Myocardial infarction
B. Hypoxia
C. Circulatory failure
D. Infections

D. Infections

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6.Which of the following conditions will NOT cause respiratory alkalosis?
A. Fever
B. Anxiety
C. Laryngeal obstruction
D. Salicylate toxicity

C. Laryngeal obstruction

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7.Which phrase is FALSE about metabolic alkalosis?
A. Associated with hyperkalemia
B. Associated with decreased ionic calcium concentration
C. Can be caused due to Primary hyperaldosteronism
D. Can be caused due to Renin secreting tumor

A. Associated with hyperkalemia

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8.Which is NOT true of hemoglobin?
A. Deoxy hemoglobin is a weak base
B. Oxyhemoglobin is a relatively strong acid
C. The buffering capacity of hemoglobin is lesser than plasma protein
D. The buffering capacity of Hemoglobin is due to histidine residues.

C. The buffering capacity of hemoglobin is lesser than plasma protein

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9.Which of the choices is not carried by the kidney in handling of acids in metabolic acidosis?
A. Hydrogen ion secretion is increased
B. Bicarbonate reabsorption is decreased
C. Urinary acidity is increased
D. Urinary ammonia is increased.

C. Urinary acidity is increased

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10.Citrate, in excess of its normal concentration in transfused blood can cause?
A Metabolic alkalosis
B. Metabolic acidosis
C. Respiratory alkalosis
D. Respiratory acidosis

B. Metabolic acidosis

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11.Which is the hydrogen ion concentration at normal arterial blood pH of 7.4?
A. 35mEq/L
B. 40mEq/L
C. 45mEq/L
D. 50mEq/L

B. 40mEq/L

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12.Which is the most powerful regulatory system/mechanism maintaining the acid-base homeostasis?
A. chemical buffer system
B. protein buffer system
C. respiratory mechanism
D. renal mechanism

D. renal mechanism

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13.Which of the following systems acts first in regulating acid-base balance?
A. chemical buffer system
B. protein buffer system
C. respiratory mechanism
D. renal mechanism

A. chemical buffer system

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14.Under normal conditions, which is the correct ratio of HCO3- to CO2 in the extracellular fluids?
A. 16:1
B. 20:1
C. 24:1
D. 28:1

B. 20:1

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15.Which of the following statement is true regarding the respiratory control of acid base balance?
A. increase in hydrogen ion concentration depresses the respiratory system
B. the respiratory system can effectively correct the hydrogen ion concentration by 20% to 50%
C. the impairment of lung function in a condition such as emphysema increases the pCO2 concentrations
D. decrease in hydrogen ions stimulates the lungs to expel more carbon dioxide

C. the impairment of lung function in a condition such as emphysema increases the pCO2 concentrations

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16.At which part of the tubular system of the kidney is the site of reclamation of bicarbonate ions?
A. Glomerulus
B. Proximal tubules
C. Loop of Henle
D. Distal tubules

B. Proximal tubules

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17.How does the kidney contributes to maintaining acid-base balance?
A. secretion of ammonia
B. reclamation of bicarbonate ions
C. increased ketogenesis
D. decreased CO2 uptake

B. reclamation of bicarbonate ions

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18.In which non-compensated acid base disequilibrium is CO2 found in excess?
A. metabolic acidosis
B. metabolic alkalosis
C. respiratory acidosis
D. respiratory alkalosis

C. respiratory acidosis

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19.Which buffer system is present at high concentration inside the cells and effective intracellularly?
A. H2CO3/HCO3- buffer system
B. albumin buffer system
C. NH3/NH2- buffer system
D. H2PO4-/HPO42- buffer system

D. H2PO4-/HPO42- buffer system

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20.Given a patient in coma with an ABG(arterial blood gas) of pCO2 = 16mmHg, HCO3- =5mmol/l and a pH = 7.1. What is the acid-base status of the patient?____
A. Metabolic Acidosis
B. Metabolic Alkalosis
C. Respiratory Acidosis
D. Respiratory Alkalosis

A. Metabolic Acidosis

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21.A patient undergoing exploratory abdominal surgery necessitated the surgeon to aspirate the contents of the upper gastrointestinal tract. After surgery, the ABG that was requested gave a pH = 7.55, pCO2 = 52mm Hg and HCO3- = 40mmol/l. What is the acid-base status of the patient?
A. Metabolic Acidosis
B. Metabolic Alkalosis
C. Respiratory Acidosis
D. Respiratory Alkalosis

B. Metabolic Alkalosis

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22.What acid-base condition is expected from a medical student nervous, breathing rapidly because of a long exam in Biochemistry?
A. Metabolic Acidosis
B. Metabolic Alkalosis
C. Respiratory Acidosis
D. Respiratory Alkalosis

D. Respiratory Alkalosis

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23.In what acid-base condition is a 45- year-old female in renal failure, who missed her dialysis for the week and was feeling sick?
A. Metabolic Acidosis
B. Metabolic Alkalosis
C. Respiratory Acidosis
D. Respiratory Alkalosis

A. Metabolic Acidosis

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24.An 90-year-old lady had a bad cold. After two weeks she said, “It went in to my chest, I am feeling tightness in my chest, I am coughing, suffocated and unable to breathe!” What might be the possible cause?
A. Metabolic Acidosis
B. Metabolic Alkalosis
C. Respiratory Acidosis
D. Respiratory Alkalosis

C. Respiratory Acidosis

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25.A post operative surgical patient had a nasogastric tube in for three days. The nurse noted much drainage from the tube. The patient is feeling so sick. What could be the acid-base status that explains the feeling of the patient ? A. Metabolic Acidosis B. Metabolic Alkalosis C. Respiratory Acidosis D. Respiratory Alkalosis

B. Metabolic Alkalosis

26.Which of the following statements is true of redox potential? A. A system with a redox potential of 0 does not participate in energy transfer reactions because it has neither protons nor electrons B. Oxygen has the highest voltage value C. Reduction potential is measured in watts instead of joules D. The lower the redox potential, the greater is the tendency to be reduced.

B. Oxygen has the highest voltage value

27.Which cytochrome catalyzes the removal of hydrogen from a substrate using oxygen as a hydrogen acceptor? A. Cytochrome oxidase B. Cytochrome b C. Cytochrome c D. Cytochrome dehydrogenase

A. Cytochrome oxidase

28.Superoxide dismutase protects aerobic organisms against oxygen toxicity. It does this by: A. Donating reducing equivalents to cytochrome P450 for superoxide dismutation B. Oxidizing free radicals formed by xenobiotics C. Enabling Glutathione to react with oxygen to form Glutathione Peroxidase D. Reducing superoxide to hydrogen peroxide

D. Reducing superoxide to hydrogen peroxide

29.This is a mixed function oxidase: A. Cytochrome P450 B. Superoxide Dismutase C. Adenylyl Kinase D. Xanthine oxidase

A. Cytochrome P450

30.In a chemical reaction, when the ▲G is highly negative, A. The reaction proceeds spontaneously B. The reaction is coupled to an exergonic reaction C. The reaction can go forward or in the reverse direction, depending on the concentration of the reactants D. All of the above

A. The reaction proceeds spontaneously

31.Which of the following enzymes allows the high-energy phosphate of ADP to be used in the synthesis of ATP? A. Adenylyl Kinases B. ATPase C. Pyrophosphatases D. Nucleoside diphosphate kinase

A. Adenylyl Kinases

32.How many high-energy bonds are present in ATP? A. 1 B. 2 C. 3 D. None

B. 2

33.Which of the following compounds is a high-energy phosphate donor? A. Glucose-6-phosphate B. Glucose-1-phosphate C. Phosphoenolpyruvate D. Adenosine Monophosphate

C. Phosphoenolpyruvate

34.ATP produced by ATP synthase in the electron transport chain occurs during: A. Substrate level phosphorylation B. Oxidative Phosphorylation C. Anaerobic glycolysis D. Lactate synthesis

B. Oxidative Phosphorylation

35.The conversion of an aldehyde to a carboxylic acid is an example of: A. Oxidation B. Reduction C. Hydration D. Dehydration

A. Oxidation

36.The beta oxidation pathway is an example of: A. Fat catabolism B. Fat anabolism C. Carbohydrate anabolism D. Carbohydrate catabolism

A. Fat catabolism

37.The terminal component of the chain of respiratory carriers found in the mitochondria: A. Oxidase B. Dehydrogenase C. Peroxidase D. Oxygenase

A. Oxidase

38.FAD accepts 2 electrons and 2 hydrogen ions in the reaction forming FADH2. This is a/an: A. Oxidase B. Dehydrogenase C. Peroxidase D. Oxygenase

B. Dehydrogenase

39.H202 + AH2 → 2H20 + A A. Oxidase B. Dehydrogenase C. Peroxidase D. Oxygenase

B. Dehydrogenase

40.The component of the respiratory chain that accepts electrons via iron-containing heme group: A. cytochromes B. Fe-S proteins C. ubiquinone D. flavoproteins

A. cytochromes

41.During the transport of electrons along the components of the respiratory chain, protons are translocated from: A. cytosol to intermembrane space B. intermembrane space to cytosol C. matrix to intermembrane space D. intermembrane space to matrix

C. matrix to intermembrane space

42.This electron transport carrier can move within the lipid bilayer of the inner mitochondrial membrane: A. Fe-S protein B. cytochrome b C. flavoprotein D. cytochrome c

D. cytochrome c

43.It accepts electrons from NADH and contains tightly bound flavin mononucleotide: A. complex I B. complex II C. complex III D. complex IV

A. complex I

44.Which complex of the respiratory chain reduces oxygen to water? A. succinate dehydrogenase B. NADH dehydrogenase C. cytochrome oxidase D. cytochrome b, c1

C. cytochrome oxidase

45.Which statement is true regarding the respiratory chain? A. The components of the respiratory chain are arranged according to increasing redox potential. B. The complexes making the respiratory chain are found in the mitochondrial matrix C. Both A and B D. Neither A nor B

A. The components of the respiratory chain are arranged according to increasing redox potential.

46.Brown adipose tissue generates heat for hibernating animals by: A. increasing ATP hydrolysis with release of a large amount of energy B. dissipating proton gradient resulting in oxidation without phosphorylation C. promoting ATP synthesis by substrate-level phosphorylation D. decreasing the rate of O2 consumption

B. dissipating proton gradient resulting in oxidation without phosphorylation

47.It inhibits oxidative phosphorylation by binding to the subunit of ATP synthase that makes up the proton channel: A. rotenone B. dinitrophenol C. atractyloside D. oligomycin

D. oligomycin

48.Why do we need oxygen in the ETC? A. Oxygen attaches to water to hydrolyze ADP to ATP B. The cleavage of the oxygen molecule yields an exergonic reaction used to fuel endergonic reactions C. It is the final electron acceptor that allows the phosphorylation of ADP D. Oxygen allows ATP synthase to turn its F0 segment during the process of uncoupling

C. It is the final electron acceptor that allows the phosphorylation of ADP

49.What is the important byproduct of the ETC that will sustain aerobic glycolysis? A. NAD+ B. NADH C. NADPH D. FADH2

A. NAD+

50.A + O2 → AO2 A. Oxidase B. Dehydrogenase C. Peroxidase D. Oxygenase

D. Oxygenase

51.What term is used to describe the resistance of pH to change in addition of H+ or OH-? A. Bond strength B. Dissociation strength C. Titration D. Buffering

D. Buffering

52.What is pH? A. The logarithm of the hydrogen ion concentration B. The negative logarithm of the hydrogen ion concentration C. The logarithm of the hydrogen ion concentration divided by the hydroxide ion concentration D. The negative logarithm of the hydrogen ion concentration divided by the hydroxide ion concentration

B. The negative logarithm of the hydrogen ion concentration

53.What is the ion product of water? A. It is the total number of negatively and positively charged ions in 1 liter of aqueous solution B. It is the product of the concentrations of hydrogen and hydroxyl ions in an aqueous solution C. It is the number of ionized molecules of water in 1 mole of pure water D. It is the sum of all hydrogen and hydroxyl ions in an aqueous solution

B. It is the product of the concentrations of hydrogen and hydroxyl ions in an aqueous solution

54.What is the property of water that will contribute the most to its ability to dissolve compounds? A. Hydrogen bond formation between water and long-chain fatty acids B. Covalent bond formation between salt and water C. Hydrogen bond formation between water and biochemical molecules D. Very few interactive forces to its structure

C. Hydrogen bond formation between water and biochemical molecules

55.Which of the following statements correctly describes the nucleolus of a mammalian cell? A. It synthesizes 5s rRNA B. It differs from that found in bacterial cells in that histones are present C. It synthesizes all ribosomal RNA transcripts D. It may contain hundreds of copies of genes for different types of ribosomal RNAs

D. It may contain hundreds of copies of genes for different types of ribosomal RNAs

56.Homeostasis includes which of the following: A. Maintenance of electrolyte concentration B. Maintenance of appropriate pH C. Consideration of water distribution in the body D. All of the above

D. All of the above

57.What is the normal range of blood pH? A. 7.25-7.65 B. 7.35-7.45 C. 6.8-7.35 D. 6.45-7.45

B. 7.35-7.45

58.A base is a substance that accepts protons. Which of the following is/are considered a base? A. OH- B. HCO3- C. HPO4- D. All of the above

D. All of the above

59.The following statements is/are true of prokaryotes: A. Multicellular B. Presence of organelles C. Presence of plasma membrane D. Presence of nuclear envelope

C. Presence of plasma membrane

60.What is the value of k (dissociation constant of water) at 25oC? A. 1.8 x 10-9 mol/L B. 1 x 10-7 mol/L C. 1.8 x 10-16 mol/L D. 55.56 M

C. 1.8 x 10-16 mol/L

61.Which is/are true of the chemical composition in major fluid compartments of the body? A. The protein content of the intracellular fluid is nearly four times that of blood plasma B. K and Mg are the predominant cations in the interstitial fluid C. Na predominates in the intracellular fluid D. All electrolytes are essentially the same in all fluid compartments

A. The protein content of the intracellular fluid is nearly four times that of blood plasma

62.The nucleus: A. Contains the chromosomes B. Serves as temporary storage of secretory substances C. Provides most of the energy for cellular function D. Houses the intracellular digestive system

A. Contains the chromosomes

63.The mitochondrial matrix contains enzymes that catalyze which of the following set of reactions? A. Citric acid cycle B. Glycolysis C. Pentose phosphate pathway D. Fatty acid synthesis

A. Citric acid cycle

64.To enter or leave a cell, a substance must pass through: A. Microtubules B. Golgi apparatus C. Plasma membrane D. Endoplasmic reticulum

C. Plasma membrane

65.The main difference between animal and plant cells: A. Animal cells lack rigid cell wall B. Animal cells have vacuoles C. Plant cells lack rigid cell wall D. Plant cells have small vacuoles

A. Animal cells lack rigid cell wall

66.Which of the following are features that differentiates cilia from flagella? A. Cilia are short compared to flagella B. Flagella are less in number compared to cilia C. Cilia are distributed throughout the cell surface D. All of the above

D. All of the above

67.Insulin and glucagon receptors are found in: A. Nucleus B. Plasma membrane C. Cytoplasm D. Mitochondrial membrane

B. Plasma membrane

68.The organelle that contains catalases and peroxidases: A. Lysosome B. Cytosol C. Peroxisome D. Vacuole

C. Peroxisome

69.The following takes place in the mitochondria, except: A. Kreb’s cycle B. Beta oxidation of fatty acids C. Glycolysis D. Oxidative phosphorylation

C. Glycolysis

70.Where phospholipid synthesis takes place: A. Plasma membrane B. Mitochondria C. Rough endoplasmic reticulum D. Smooth endoplasmic reticulum

D. Smooth endoplasmic reticulum

71.Which of the following is a biologic role of water? A. It stabilizes the three-dimensional structure of proteins. B. It stabilizes the three-dimensional structure of nucleic acids. C. It is a common medium used in most enzyme catalysis. D. A & C only E. All of the Above

E. All of the Above

72.Which of the following statements is TRUE regarding a prokaryotic cell? A. It contains an ill-defined nucleolus. B. It contains DNA that is associated with histones. C. It is capable of carrying out electron transport and oxidative phosphorylation. D. A & C only

A. It contains an ill-defined nucleolus.

73.Which of the following organelles is double-membraned? A. Nucleus B. Endoplasmic reticulum C. Mitochondria D. A & C only E. All of the Above

D. A & C only

74.Which of the following statements is true of water ionization? A. Hydrogen and hydroxyl concentrations are equal at 25oC being 1.6x10-7 M B. Hydrogen and hydroxyl ion concentrations are equal at 37oC being 1x10-7 M C. Ion product of water (kw) is at 1x10-14 (moles/L)2 D. OH- in the ionization of water molecule is referred to as a hydrated proton

C. Ion product of water (kw) is at 1x10-14 (moles/L)2

75.Ribosomes help in: A. Photosynthesis B. Lipid synthesis C. Protein synthesis D. Respiration

C. Protein synthesis

76.A 70-kg adult would require about this much protein in the diet a. 240-360 kcal/day b. 960-1440 kcal/day c. 720-960 kccal/day d. 1800-2400 kcal/day

a. 240-360 kcal/day

77.Average physical activity increases metabolic rate by about how many percent over the resting metabolic rate? a. 10-15% b. 20-30% c. 40-50% d. 70-80%

c. 40-50%

78.Synthesis of proteins is an example of A. Catabolic process B. Anabolic process C. Amphibolic process D. None

B. Anabolic process

79.The following are example/s of anabolic processes A. Synthesis of triacylglycerides (TAGs) B. Oxidative phosphorylation C. Both D. Neither

A. Synthesis of triacylglycerides (TAGs)

80.Citric acid cycle is an example of a. Anabolic process b. Catabolic process c. Amphibolic process d. None

c. Amphibolic process

81.This occurs when intake of metabolic fuels is consistently greater than energy expenditure A. Emaciation B. Obesity C. Fasting D. Starvation

B. Obesity

82.Acetyl coA is oxidized by this cycle before complete oxidation to CO2 and H2O A. Pentose phosphate pathway B. Oxidative phosphorylation C. Citric acid cycle D. Glycolysis

C. Citric acid cycle

83.Precursors for gluconeogenesis include the following except: A. Glycerol B. Pyruvate C. Alanine D. Acetyl coA

D. Acetyl coA

84. Impaired sensitivity of tissues to insulin action causes A. DM type I B. DM type 2 C. Both D. None

B. DM type 2

85.Source of NADPH and ribose: A. Citric acid cycle B. Glycolysis C. Pentose phosphate pathway D. Both A & C

C. Pentose phosphate pathway

86.In the absence of oxygen, the product of glycolysis yields a. Pyruvate b. ATP c. Lactate d. Glycerol

c. Lactate

87.Fatty acids undergo esterification to yield a. Triacylglycerol b. Acetyl coA c. Chylomicrons d. Cholesterol

a. Triacylglycerol

88.Lipids in the diet as TAGS are secreted into the bloodstream via a. Portal vein b. Chylomicrons c. Hepatic vein d. None

b. Chylomicrons

89.Gluconeogenesis occurs in the: a. Cytosol b. Mitochondrion c. Both d. None

c. Both

90.In the fasting state, glucose must be spared for use by: a. CNS b. RBC c. Muscle d. A & B

d. A & B

91.The following are actions of insulin except A. Stimulate glycogen synthase B. Inhibit glycogen phosphorylase C. Migration of GLUT-4 transporter from the cell surface to the internal vesicles D. None of the above

C. Migration of GLUT-4 transporter from the cell surface to the internal vesicles

92.This enzyme catalyzes the hydrolysis of Glu-6-PO4 to release glucose during the fasting state A. Glucose-6-phosphatase B. Glycogen phosphorylase C. Glucose-6-phosphorylase D. Glycogen synthetase

A. Glucose-6-phosphatase

93.In the fasting state, action of glucagon results in the following except A. Inhibition of lipogenesis B. Activation of glycogen synthase C. Activation of intracellular lipase D. Activation of glycogen phosphorylase

B. Activation of glycogen synthase

94.In prolonged starvation, the major metabolic fuel in the body is A. Free fatty acids B. Ketone bodies C. Glucose D. Urea

B. Ketone bodies

95.Muscle glycogen contributes during fasting by: A. Releasing glucose from breakdown of glycogen stores B. Pyruvate from glycolysis is transaminated to alanine and transported to the liver for gluconeogenesis C. Releasing oxygen via anaerobic glycolysis D. No contribution during fasting

B. Pyruvate from glycolysis is transaminated to alanine and transported to the liver for gluconeogenesis

96.After deamination, amino nitrogen is excreted as A. Ammonia B. Urea C. Creatinine D. Glutamate

B. Urea

97.Lipids from the diet carried by chylomicrons are first metabolized by tissues that have the enzyme: A. Lipoxygenase B. Lipoprotein phosphatase C. Hexokinase D. Lipoprotein lipase

D. Lipoprotein lipase

98.This organelle contains the enzyme system for triacylglycerol synthesis: A. Mitochondrion B. Ribosome C. Endoplasmic reticulum D. Cytosol

C. Endoplasmic reticulum

99.Amino acids that give rise to acetyl coA are: A. Glucogenic B. Ketogenic C. Gluconeogenic D. None of the above

B. Ketogenic

100.In skeletal muscle, migration of glucose transporter is stimulated by A. Insulin B. Glucagon C. Chylomicrons D. Increase cytoplasmic Ca2+

D. Increase cytoplasmic Ca2+