1st Biochemistry Lecture Exam (Batch 2026) Flashcards
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
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
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
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
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
6.Which of the following conditions will NOT cause respiratory alkalosis?
A. Fever
B. Anxiety
C. Laryngeal obstruction
D. Salicylate toxicity
C. Laryngeal obstruction
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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