Biological significance of ATP MCQs With Answer

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Biological significance of ATP MCQs With Answer is a must-read for B. Pharm students aiming to master cellular bioenergetics and pharmacological implications. This SEO-friendly introduction explains ATP’s structure, synthesis (glycolysis, TCA, oxidative phosphorylation), hydrolysis energetics, ATP-dependent enzymes (kinases, ATPases), signaling roles (cAMP, purinergic receptors), and drug interactions affecting mitochondrial ATP production. Emphasis on ATP as the universal energy currency, its regulatory control via AMP/ATP ratios and AMPK, and clinical relevance will strengthen exam readiness and practical understanding. These MCQs include answers and brief explanations to deepen comprehension and application in pharmaceutical contexts. ‘Now let’s test your knowledge with 50 MCQs on this topic.’

Q1. What does ATP stand for?

  • Adenosine triphosphate
  • Adenine triphosphide
  • Adenosine tetraphosphate
  • Adenosine diphosphate

Correct Answer: Adenosine triphosphate

Q2. What is the primary biological role of ATP in cells?

  • Long-term energy storage
  • Signal molecule only
  • Universal energy currency for biochemical reactions
  • Structural component of membranes

Correct Answer: Universal energy currency for biochemical reactions

Q3. The standard free energy change (ΔG°’) for ATP hydrolysis to ADP + Pi is approximately:

  • +30.5 kJ/mol
  • -30.5 kJ/mol
  • -7.3 J/mol
  • 0 kJ/mol

Correct Answer: -30.5 kJ/mol

Q4. Where is most cellular ATP produced in aerobic eukaryotic cells?

  • Cytosol via glycolysis
  • Mitochondrial matrix by substrate-level phosphorylation only
  • Inner mitochondrial membrane via oxidative phosphorylation (ATP synthase)
  • Golgi apparatus

Correct Answer: Inner mitochondrial membrane via oxidative phosphorylation (ATP synthase)

Q5. Which glycolytic enzymes perform substrate-level phosphorylation to directly generate ATP?

  • Hexokinase and phosphofructokinase
  • Phosphoglycerate kinase and pyruvate kinase
  • Aldolase and enolase
  • Glyceraldehyde-3-phosphate dehydrogenase and triose phosphate isomerase

Correct Answer: Phosphoglycerate kinase and pyruvate kinase

Q6. The F1F0-ATP synthase synthesizes ATP using which driving force?

  • Electron flow through NADH oxidase
  • Proton motive force across the inner mitochondrial membrane
  • ATP hydrolysis in the cytosol
  • Direct light absorption in mitochondria

Correct Answer: Proton motive force across the inner mitochondrial membrane

Q7. Which compound is a specific inhibitor of ATP synthase?

  • Oligomycin
  • Rotenone
  • Antimycin A
  • Cyanide

Correct Answer: Oligomycin

Q8. Which molecule acts as an uncoupler of oxidative phosphorylation by dissipating the proton gradient?

  • Oligomycin
  • 2,4-Dinitrophenol (DNP)
  • ATP
  • Succinate

Correct Answer: 2,4-Dinitrophenol (DNP)

Q9. Rotenone, an inhibitor of the electron transport chain, primarily blocks which complex?

  • Complex I (NADH dehydrogenase)
  • Complex II (succinate dehydrogenase)
  • Complex III (cytochrome bc1)
  • Complex IV (cytochrome c oxidase)

Correct Answer: Complex I (NADH dehydrogenase)

Q10. Which inhibitor binds to cytochrome c oxidase and blocks electron transfer to oxygen?

  • Cyanide
  • Oligomycin
  • Carbonic anhydrase inhibitor
  • Rotenone

Correct Answer: Cyanide

Q11. Net ATP gain from anaerobic glycolysis per molecule of glucose is:

  • 0 ATP
  • 2 ATP
  • 4 ATP
  • 36 ATP

Correct Answer: 2 ATP

Q12. How many GTP (or equivalent ATP) molecules are produced directly in one turn of the TCA cycle?

  • 0
  • 1
  • 2
  • 4

Correct Answer: 1

Q13. Approximately how many ATP molecules are generated from complete aerobic oxidation of one glucose in typical eukaryotic cells?

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

Correct Answer: Approximately 30–32 ATP molecules

Q14. Which class of enzymes transfers a phosphate group from ATP to an acceptor molecule?

  • Oxidoreductases
  • Kinases
  • Ligases
  • Lyases

Correct Answer: Kinases

Q15. cAMP is synthesized from ATP by which enzyme?

  • Adenylate cyclase
  • Guanylate cyclase
  • Adenylyl kinase
  • ATP synthase

Correct Answer: Adenylate cyclase

Q16. Which enzyme catalyzes the reversible reaction 2 ADP ⇌ ATP + AMP, important for cellular adenylate balance?

  • Adenylate kinase (myokinase)
  • AMP deaminase
  • ATP synthase
  • Hexokinase

Correct Answer: Adenylate kinase (myokinase)

Q17. The high-energy bond hydrolyzed during ATP → ADP + Pi is called the:

  • Glycosidic bond
  • Phosphoester bond
  • Phosphoanhydride (terminal γ) bond
  • Peptide bond

Correct Answer: Phosphoanhydride (terminal γ) bond

Q18. Which muscle protein has ATPase activity critical for muscle contraction?

  • Tropomyosin
  • Actin
  • Myosin (myosin ATPase)
  • Titin

Correct Answer: Myosin (myosin ATPase)

Q19. The Na+/K+ pump is classified as which type of ATPase?

  • F-type ATPase
  • V-type ATPase
  • P-type ATPase
  • ABC transporter

Correct Answer: P-type ATPase

Q20. A common laboratory method to measure ATP concentration uses which bioluminescent enzyme?

  • Peroxidase
  • Luciferase
  • Alkaline phosphatase
  • Dehydrogenase

Correct Answer: Luciferase

Q21. Which non-hydrolyzable ATP analog is commonly used to study ATP-dependent enzymes?

  • ATPγS or AMP-PNP
  • ADP
  • GTP
  • cAMP

Correct Answer: ATPγS or AMP-PNP

Q22. In rapidly contracting muscle, the immediate regeneration of ATP is supported by which system?

  • Glycogen synthesis
  • Creatine kinase system (phosphocreatine)
  • Fatty acid β-oxidation
  • Urea cycle

Correct Answer: Creatine kinase system (phosphocreatine)

Q23. The P/O ratio indicates ATP produced per atom of oxygen reduced; the commonly accepted P/O for NADH is about:

  • 0.5
  • 1.5
  • 2.5
  • 4.0

Correct Answer: 2.5

Q24. Which TCA cycle enzyme catalyzes the step that generates GTP (or ATP) by substrate-level phosphorylation?

  • Citrate synthase
  • Isocitrate dehydrogenase
  • Succinyl-CoA synthetase (succinate thiokinase)
  • α-Ketoglutarate dehydrogenase

Correct Answer: Succinyl-CoA synthetase (succinate thiokinase)

Q25. Which transporter exchanges mitochondrial ATP for cytosolic ADP across the inner mitochondrial membrane?

  • Glucose transporter (GLUT)
  • ATP/ADP translocase (ANT)
  • Sodium-glucose cotransporter
  • V-type ATPase

Correct Answer: ATP/ADP translocase (ANT)

Q26. AMP-activated protein kinase (AMPK) is activated when the cellular energy charge shows:

  • High ATP and low AMP
  • High AMP relative to ATP (low energy state)
  • High glucose only
  • High oxygen concentration

Correct Answer: High AMP relative to ATP (low energy state)

Q27. Which of the following links the TCA cycle to the electron transport chain as an integral membrane complex?

  • ATP synthase (Complex V)
  • Succinate dehydrogenase (Complex II)
  • Pyruvate dehydrogenase
  • Malate dehydrogenase

Correct Answer: Succinate dehydrogenase (Complex II)

Q28. Which factor most strongly affects the actual free energy change (ΔG) of ATP hydrolysis in a living cell?

  • Standard ΔG°’ value only
  • Concentrations of ATP, ADP, and inorganic phosphate (Pi)
  • Molecular weight of ATP
  • pH of 7.0 only

Correct Answer: Concentrations of ATP, ADP, and inorganic phosphate (Pi)

Q29. Extracellular ATP acting on purinergic receptors most directly modulates which physiological response?

  • DNA replication fidelity
  • Vasodilation/vasoconstriction and neurotransmission
  • Protein folding in the ER
  • Cholesterol synthesis

Correct Answer: Vasodilation/vasoconstriction and neurotransmission

Q30. Deficiency of which enzyme in purine metabolism is associated with severe combined immunodeficiency (SCID) and affects nucleotide pools?

  • Adenosine deaminase (ADA)
  • Xanthine oxidase
  • Purine nucleoside phosphorylase (PNP)
  • Ribonucleotide reductase

Correct Answer: Adenosine deaminase (ADA)

Q31. Which family of transporters uses ATP hydrolysis to export a wide range of substrates across membranes and is important in drug resistance?

  • Glucose transporters (GLUT)
  • ABC (ATP-binding cassette) transporters
  • Sodium-potassium pump
  • Vesicular monoamine transporters (VMAT)

Correct Answer: ABC (ATP-binding cassette) transporters

Q32. Many antiviral nucleoside analogue prodrugs require intracellular phosphorylation by kinases using ATP for activation. Which step is ATP-dependent?

  • Conversion to nucleobase
  • Initial monophosphorylation by kinases
  • Excretion from the cell
  • Incorporation into glycogen

Correct Answer: Initial monophosphorylation by kinases

Q33. Which organelle besides mitochondria is capable of photophosphorylation to synthesize ATP?

  • Lysosome
  • Chloroplast (thylakoid membrane)
  • Endoplasmic reticulum
  • Peroxisome

Correct Answer: Chloroplast (thylakoid membrane)

Q34. ATP contains which three main chemical components?

  • Adenine base, deoxyribose sugar, two phosphates
  • Adenine base, ribose sugar, three phosphate groups
  • Guanine base, ribose sugar, three phosphate groups
  • Cytosine base, deoxyribose sugar, three phosphates

Correct Answer: Adenine base, ribose sugar, three phosphate groups

Q35. Which ion is essential to stabilize ATP in cells and forms a complex with ATP?

  • Na+
  • Mg2+
  • Cl-
  • Fe2+

Correct Answer: Mg2+

Q36. Which enzyme catalyzes the charging of tRNA with amino acids and consumes ATP?

  • Ribosomal peptidyl transferase
  • Aminoacyl-tRNA synthetase
  • Elongation factor EF-Tu
  • Initiation factor IF-1

Correct Answer: Aminoacyl-tRNA synthetase

Q37. ATP hydrolysis by which enzyme family is required for unwinding DNA during replication?

  • Topoisomerases (type I only)
  • ATP-dependent helicases
  • DNA ligases
  • Ribozymes

Correct Answer: ATP-dependent helicases

Q38. Which type of ATPase acidifies intracellular compartments like lysosomes and endosomes?

  • P-type ATPase
  • F-type ATPase
  • V-type (vacuolar) ATPase
  • ABC transporter

Correct Answer: V-type (vacuolar) ATPase

Q39. Which drug commonly used in diabetes is known to inhibit complex I of the mitochondrial respiratory chain, reducing ATP production?

  • Insulin
  • Metformin
  • Glipizide
  • Pioglitazone

Correct Answer: Metformin

Q40. The electron acceptor at the end of the mitochondrial electron transport chain is:

  • Nitrate
  • Carbon dioxide
  • Oxygen
  • Fumarate

Correct Answer: Oxygen

Q41. In biochemical assays, why is measuring the ATP/ADP ratio important?

  • It determines membrane composition
  • It indicates cellular energy status and metabolic regulation
  • It measures DNA replication rate directly
  • It quantifies protein glycosylation

Correct Answer: It indicates cellular energy status and metabolic regulation

Q42. Which enzyme converts ATP to cAMP and is regulated by G-protein coupled receptors?

  • Guanylate cyclase
  • Adenylate cyclase
  • Phosphodiesterase
  • Protein kinase A

Correct Answer: Adenylate cyclase

Q43. Which mitochondrial carrier protein is responsible for importing inorganic phosphate (Pi) needed for ATP synthesis?

  • Phosphate carrier (Pi transporter)
  • Glucose-6-phosphate transporter
  • ATP/ADP translocase
  • Citrate transporter

Correct Answer: Phosphate carrier (Pi transporter)

Q44. Which statement about ATP in signal transduction is correct?

  • ATP is only an energy molecule and not used in signaling
  • ATP is a phosphate donor in phosphorylation cascades and serves as precursor for second messengers like cAMP
  • ATP permanently binds receptors and cannot be hydrolyzed
  • ATP functions exclusively in the nucleus for transcription

Correct Answer: ATP is a phosphate donor in phosphorylation cascades and serves as precursor for second messengers like cAMP

Q45. Which experimental change would most directly lower the rate of oxidative ATP synthesis in intact mitochondria?

  • Increase ADP concentration
  • Add oligomycin to inhibit ATP synthase
  • Add succinate to the medium
  • Increase oxygen supply

Correct Answer: Add oligomycin to inhibit ATP synthase

Q46. The majority of ATP generated in mitochondria is produced during which process?

  • Substrate-level phosphorylation in glycolysis
  • Oxidative phosphorylation coupled to the electron transport chain
  • Fermentation
  • Protein degradation

Correct Answer: Oxidative phosphorylation coupled to the electron transport chain

Q47. Which enzyme converts AMP to IMP during purine nucleotide interconversion and is important in maintaining nucleotide balance?

  • Adenylate kinase
  • Adenosine deaminase
  • Adenosine monophosphate deaminase (AMP deaminase)
  • Xanthine oxidase

Correct Answer: Adenosine monophosphate deaminase (AMP deaminase)

Q48. In bacterial chemiosmosis, where is ATP synthase located?

  • Cytosol
  • Inner mitochondrial membrane
  • Plasma membrane
  • Cell wall

Correct Answer: Plasma membrane

Q49. Which phase of oxidative phosphorylation is directly responsible for converting ADP + Pi into ATP?

  • Electron donation to complex I only
  • Proton pumping creating proton motive force followed by F1F0-ATP synthase activity
  • Substrate-level phosphorylation in the TCA cycle exclusively
  • Direct phosphate transfer from NADH

Correct Answer: Proton pumping creating proton motive force followed by F1F0-ATP synthase activity

Q50. Is ATP required for apoptosome assembly and some steps of apoptosis?

  • No, apoptosis is entirely ATP-independent
  • Yes, certain apoptosis processes and apoptosome assembly require ATP/dATP
  • ATP prevents apoptosis in all cases
  • ATP is only needed for necrosis, not apoptosis

Correct Answer: Yes, certain apoptosis processes and apoptosome assembly require ATP/dATP

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