Role of ATP MCQs With Answer

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Role of ATP MCQs With Answer are vital study tools for B.Pharm students seeking mastery in pharmacology, biochemistry, and therapeutics. This focused introduction emphasizes ATP structure, biosynthesis (glycolysis, Krebs cycle, oxidative phosphorylation), ATP-dependent transporters, ATPases, energy transfer, and clinical implications such as ischemia and mitochondrial disorders. Practicing targeted multiple-choice questions strengthens conceptual understanding of ATP hydrolysis, enzyme regulation, drug interactions affecting ATP pathways, and diagnostic markers. These MCQs bridge core theory and exam application, helping you analyze mechanisms, predict drug effects, and improve recall under test conditions. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which of the following is the primary role of ATP in cells?

  • Structural component of the cell membrane
  • Carrier of genetic information
  • Immediate donor of free energy for biochemical reactions
  • Long-term energy storage molecule

Correct Answer: Immediate donor of free energy for biochemical reactions

Q2. What are the products of ATP hydrolysis under physiological conditions?

  • Adenosine and pyrophosphate
  • Adenosine diphosphate (ADP) and inorganic phosphate (Pi)
  • Adenosine monophosphate (AMP) and water
  • Adenine and ribose

Correct Answer: Adenosine diphosphate (ADP) and inorganic phosphate (Pi)

Q3. Where does oxidative phosphorylation occur in eukaryotic cells?

  • Rough endoplasmic reticulum
  • Outer mitochondrial membrane
  • Inner mitochondrial membrane
  • Cytosol

Correct Answer: Inner mitochondrial membrane

Q4. Net ATP produced directly by glycolysis per glucose molecule is:

  • 1 ATP
  • 2 ATP
  • 4 ATP
  • 6 ATP

Correct Answer: 2 ATP

Q5. Which enzyme catalyzes the synthesis of ATP in oxidative phosphorylation?

  • ATP synthase (F1F0-ATPase)
  • Hexokinase
  • Pyruvate kinase
  • Adenylate kinase

Correct Answer: ATP synthase (F1F0-ATPase)

Q6. The chemiosmotic theory of ATP synthesis was proposed by:

  • Emil Fischer
  • Peter Mitchell
  • Linus Pauling
  • Albert Szent-Györgyi

Correct Answer: Peter Mitchell

Q7. Which of the following inhibitors blocks complex IV of the electron transport chain?

  • Rotenone
  • Antimycin A
  • Cyanide
  • Oligomycin

Correct Answer: Cyanide

Q8. Oligomycin specifically inhibits which mitochondrial component?

  • Complex I
  • ATP synthase
  • Complex III
  • Succinate dehydrogenase

Correct Answer: ATP synthase

Q9. Which compound acts as an uncoupler of oxidative phosphorylation by dissipating the proton gradient?

  • Dinitrophenol (DNP)
  • Oligomycin
  • Rotenone
  • Cyanide

Correct Answer: Dinitrophenol (DNP)

Q10. How many high-energy phosphate bonds are cleaved when ATP is hydrolyzed to ADP and Pi?

  • One
  • Two
  • Three
  • None

Correct Answer: One

Q11. Creatine kinase catalyzes which reversible reaction important in rapid ATP buffering?

  • Creatine + ATP ⇌ Creatine phosphate + ADP
  • Creatine phosphate + ADP ⇌ Creatine + ATP
  • Creatine + ADP ⇌ Creatine phosphate + AMP
  • Creatine phosphate + ATP ⇌ Creatine + ADP

Correct Answer: Creatine phosphate + ADP ⇌ Creatine + ATP

Q12. The adenylate kinase (myokinase) reaction is important for maintaining adenine nucleotide balance. Its net reaction is:

  • ATP + AMP ⇌ 2 ADP
  • 2 ADP ⇌ ATP + AMP
  • ATP + ADP ⇌ 2 AMP
  • 2 ATP ⇌ ADP + AMP

Correct Answer: 2 ADP ⇌ ATP + AMP

Q13. Which membrane transporter directly uses ATP to pump Na+ out and K+ into the cell?

  • Voltage-gated Na+ channel
  • Na+/K+ ATPase
  • Na+/K+ co-transporter
  • Glucose transporter (GLUT)

Correct Answer: Na+/K+ ATPase

Q14. ABC transporters are characterized by which feature related to ATP?

  • They synthesize ATP
  • They bind and hydrolyze ATP to drive substrate transport
  • They are inhibited by ATP
  • They export ATP to extracellular space

Correct Answer: They bind and hydrolyze ATP to drive substrate transport

Q15. Which cellular condition activates AMP-activated protein kinase (AMPK)?

  • High ATP/ADP ratio
  • High ATP/AMP ratio
  • High AMP/ATP ratio (low energy state)
  • Low ADP concentration

Correct Answer: High AMP/ATP ratio (low energy state)

Q16. Which complex of the electron transport chain contains flavin mononucleotide (FMN)?

  • Complex II
  • Complex I
  • Complex III
  • Complex IV

Correct Answer: Complex I

Q17. ATP serves as a substrate for which class of enzymes critical in signal transduction?

  • Phosphatases
  • Glycosidases
  • Kinases
  • Proteases

Correct Answer: Kinases

Q18. What is the immediate energetic consequence in cells when Na+/K+ ATPase is inhibited?

  • Increased ATP synthesis
  • Membrane depolarization and cellular swelling
  • Enhanced protein synthesis
  • Increased mitochondrial biogenesis

Correct Answer: Membrane depolarization and cellular swelling

Q19. Which phosphate bond in ATP is commonly referred to as the “high-energy” bond most often cleaved?

  • Alpha bond (between adenine and ribose)
  • Gamma bond (terminal phosphate)
  • Beta bond (between phosphate groups)
  • Glycosidic bond

Correct Answer: Gamma bond (terminal phosphate)

Q20. Substrate-level phosphorylation occurs in which of the following metabolic steps?

  • Electron transport chain
  • Oxidative phosphorylation only
  • Glycolysis and Krebs cycle
  • Fatty acid β-oxidation

Correct Answer: Glycolysis and Krebs cycle

Q21. Which enzyme in glycolysis catalyzes a substrate-level phosphorylation to form ATP?

  • Hexokinase
  • Phosphofructokinase-1
  • Pyruvate kinase
  • Glyceraldehyde-3-phosphate dehydrogenase

Correct Answer: Pyruvate kinase

Q22. Which nucleotide is directly phosphorylated by kinases using ATP as phosphate donor?

  • GTP only
  • ADP to form ATP
  • UDP to form UTP
  • Cyclic AMP to form ATP

Correct Answer: UDP to form UTP

Q23. A mutation in mitochondrial DNA affects complex I assembly. Which major cellular outcome is most likely?

  • Enhanced ATP production
  • Reduced oxidative phosphorylation and ATP deficiency
  • Unchanged cellular energetics
  • Increased glycolytic ATP without effect on mitochondria

Correct Answer: Reduced oxidative phosphorylation and ATP deficiency

Q24. Which ion pump in the stomach uses ATP to secrete H+ into the gastric lumen?

  • V-type H+ ATPase
  • P-type H+/K+ ATPase (proton pump)
  • Na+/H+ exchanger
  • Cl−/HCO3− antiporter

Correct Answer: P-type H+/K+ ATPase (proton pump)

Q25. Which statement best describes the standard free energy change (ΔG°’) of ATP hydrolysis?

  • Highly endergonic under physiological conditions
  • Approximately zero
  • Exergonic, releasing energy usable by cellular reactions
  • Always identical in all cellular compartments

Correct Answer: Exergonic, releasing energy usable by cellular reactions

Q26. Which of the following is a clinical consequence of ischemia related to ATP depletion?

  • Activation of Na+/K+ ATPase
  • Failure of ion pumps leading to cell swelling
  • Excessive ATP synthesis
  • Increased protein glycosylation

Correct Answer: Failure of ion pumps leading to cell swelling

Q27. Extracellular ATP can act as a signaling molecule by binding to which receptors?

  • Nicotinic acetylcholine receptors
  • P2 purinergic receptors
  • Adrenergic receptors
  • Insulin receptors

Correct Answer: P2 purinergic receptors

Q28. Which enzyme regenerates ATP from ADP using energy from substrate-level phosphorylation in the Krebs cycle?

  • Succinate dehydrogenase
  • Succinyl-CoA synthetase (succinyl-CoA ligase)
  • Citrate synthase
  • Isocitrate dehydrogenase

Correct Answer: Succinyl-CoA synthetase (succinyl-CoA ligase)

Q29. Rotenone inhibits which electron transport complex?

  • Complex IV
  • Complex II
  • Complex I
  • Complex III

Correct Answer: Complex I

Q30. Which protein motif is commonly associated with ATP binding in many ATPases?

  • Zinc finger
  • Leucine zipper
  • Walker A (P-loop) motif
  • EF-hand

Correct Answer: Walker A (P-loop) motif

Q31. Which of these drugs is known to inhibit the Na+/K+ ATPase and is used in heart failure?

  • Propranolol
  • Digoxin
  • Aspirin
  • Metformin

Correct Answer: Digoxin

Q32. In mitochondria, the proton gradient established across the inner membrane is composed of which components?

  • Only electrical potential (Δψ)
  • Only chemical (pH) gradient (ΔpH)
  • Both electrical (Δψ) and chemical (ΔpH) components
  • Neither; gradient is of Ca2+ ions

Correct Answer: Both electrical (Δψ) and chemical (ΔpH) components

Q33. What role does ATP play in ABC drug efflux pumps in cancer cells?

  • ATP blocks drug binding
  • ATP hydrolysis provides energy to export drugs out of cells
  • ATP is exported instead of drugs
  • ATP degrades the drug intracellularly

Correct Answer: ATP hydrolysis provides energy to export drugs out of cells

Q34. Which reaction indicates formation of ATP by oxidative phosphorylation?

  • ADP + Pi → ATP driven by proton flow through ATP synthase
  • ADP + Pi → ATP catalyzed by hexokinase
  • AMP + Pi → ATP in cytosol
  • GTP + ADP → GDP + ATP directly

Correct Answer: ADP + Pi → ATP driven by proton flow through ATP synthase

Q35. Which cellular enzyme converts ATP to cyclic AMP (cAMP)?

  • Adenylyl cyclase
  • Phosphodiesterase
  • Guanylyl cyclase
  • Adenylate kinase

Correct Answer: Adenylyl cyclase

Q36. In conditions of hypoxia, which metabolic pathway increases to partially compensate for reduced mitochondrial ATP production?

  • Gluconeogenesis
  • Fatty acid oxidation
  • Glycolysis (anaerobic)
  • Oxidative phosphorylation increases

Correct Answer: Glycolysis (anaerobic)

Q37. Which complex of the electron transport chain directly transfers electrons to oxygen?

  • Complex II
  • Complex I
  • Complex IV (cytochrome c oxidase)
  • Complex III

Correct Answer: Complex IV (cytochrome c oxidase)

Q38. Which molecule directly stimulates ATP synthesis by donating electrons to the ETC from the citric acid cycle?

  • Glucose
  • NADH and FADH2
  • Pyruvate only
  • ADP only

Correct Answer: NADH and FADH2

Q39. Which enzyme family hydrolyzes ATP to pump protons into lysosomes and endosomes?

  • P-type ATPases
  • V-type (vacuolar) H+ ATPases
  • F-type ATPases
  • ABC transporters

Correct Answer: V-type (vacuolar) H+ ATPases

Q40. Which statement best describes ATP’s role in muscle contraction?

  • ATP binds to actin to cause contraction
  • ATP binds to myosin, allowing cross-bridge detachment and powering the power stroke
  • ATP is not involved in muscle contraction
  • ATP directly phosphorylates tropomyosin causing contraction

Correct Answer: ATP binds to myosin, allowing cross-bridge detachment and powering the power stroke

Q41. Which process converts ADP to ATP using energy from GTP in the mitochondrion?

  • Oxidative deamination
  • GTP + ADP → GDP + ATP via nucleoside diphosphate kinase
  • Direct phosphorylation by creatine kinase
  • ATP synthase converts GTP to ATP directly

Correct Answer: GTP + ADP → GDP + ATP via nucleoside diphosphate kinase

Q42. Measurement of intracellular ATP is commonly used as an indicator of what cellular property?

  • Cell viability and metabolic activity
  • DNA replication rate
  • Lipid synthesis capacity
  • Extracellular signaling intensity

Correct Answer: Cell viability and metabolic activity

Q43. Which vitamin-derived coenzyme is directly involved in transferring electrons to the electron transport chain as NADH?

  • Vitamin C (ascorbate)
  • Niacin (NAD+)
  • Riboflavin (FAD)
  • Pyridoxine (PLP)

Correct Answer: Niacin (NAD+)

Q44. The ATP yield from complete oxidation of one molecule of glucose in eukaryotic cells is approximately:

  • 2 ATP
  • 10 ATP
  • 30–32 ATP
  • 100 ATP

Correct Answer: 30–32 ATP

Q45. Which transporter uses ATP hydrolysis to move drugs across membranes and contributes to multidrug resistance?

  • GLUT1
  • P-glycoprotein (an ABC transporter)
  • Na+/glucose cotransporter
  • SGLT2

Correct Answer: P-glycoprotein (an ABC transporter)

Q46. Which statement is true regarding ATP and nucleotide structure?

  • ATP contains a deoxyribose sugar
  • ATP contains a ribose sugar and three phosphate groups
  • ATP contains two phosphate groups and uracil
  • ATP is a lipid-derived molecule

Correct Answer: ATP contains a ribose sugar and three phosphate groups

Q47. Which enzyme is directly inhibited by cyanide leading to cessation of ATP production?

  • ATP synthase
  • Cytochrome c oxidase (Complex IV)
  • Succinate dehydrogenase (Complex II)
  • Pyruvate dehydrogenase

Correct Answer: Cytochrome c oxidase (Complex IV)

Q48. What is the effect of 2,4-dinitrophenol (DNP) on cellular respiration?

  • Inhibits electron transport chain directly
  • Uncouples oxidative phosphorylation, increasing oxygen consumption but decreasing ATP synthesis
  • Activates ATP synthase to produce more ATP
  • Blocks glycolysis

Correct Answer: Uncouples oxidative phosphorylation, increasing oxygen consumption but decreasing ATP synthesis

Q49. During heavy exercise when oxygen is limited, lactate production helps regenerate which molecule to sustain glycolysis?

  • ATP directly
  • NAD+
  • FAD
  • Oxaloacetate

Correct Answer: NAD+

Q50. Which enzyme family transfers phosphate from ATP to substrate molecules, playing a central role in signaling and metabolism?

  • Hydrolases
  • Kinases
  • Isomerases
  • Ligases

Correct Answer: Kinases

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