Types of biosensors MCQs With Answer

Types of biosensors MCQs With Answer

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Introduction: This quiz collection on Types of Biosensors is designed specifically for M.Pharm students preparing for Advanced Pharmaceutical Biotechnology examinations. It covers fundamental and advanced aspects of biosensor classification, including electrochemical, optical, piezoelectric, affinity-based and whole-cell sensors. Questions emphasize principles of transduction, biological recognition elements, immobilization strategies, signal amplification, analytical performance metrics (sensitivity, limit of detection, linear range), and practical applications in drug analysis, therapeutic monitoring and point-of-care diagnostics. Each MCQ is crafted to deepen conceptual understanding and to connect theoretical kinetics and surface chemistry with real-world biosensor design and interpretation of experimental data.

Q1. What defines a biosensor primarily?

  • A device that stores biological samples for later analysis
  • An analytical device combining a biological recognition element with a transducer
  • A separation technique for biomolecules based on size
  • A computational algorithm for analyzing biomolecular data

Correct Answer: An analytical device combining a biological recognition element with a transducer

Q2. Which transduction method measures change in current as the primary analytical signal?

  • Potentiometric
  • Amperometric
  • Optical interferometry
  • Quartz crystal microbalance

Correct Answer: Amperometric

Q3. In an enzyme-based amperometric biosensor, which parameter most directly reflects enzyme catalytic activity?

  • Open circuit potential
  • Steady-state current proportional to substrate concentration
  • Mass change on the sensor surface
  • Light absorbance shift at the sensor

Correct Answer: Steady-state current proportional to substrate concentration

Q4. Which immobilization method provides covalent attachment of enzymes to the transducer surface, minimizing leaching?

  • Physical adsorption
  • Entrapment in a hydrogel
  • Cross-linking via glutaraldehyde
  • Physisorption on hydrophobic surface

Correct Answer: Cross-linking via glutaraldehyde

Q5. Which biosensor type uses surface plasmon resonance (SPR) as its transduction principle?

  • Electrochemical conductometric sensor
  • Optical affinity sensor for label-free binding kinetics
  • Piezoelectric mass sensor measuring frequency shifts
  • Fluorescence polarization immunoassay

Correct Answer: Optical affinity sensor for label-free binding kinetics

Q6. Langmuir isotherm modeling in affinity biosensors is primarily used to determine which parameter?

  • Electron transfer rate at the electrode
  • Equilibrium dissociation constant (Kd) for ligand–receptor binding
  • Photobleaching rate of fluorescent tags
  • Acoustic damping of the sensor crystal

Correct Answer: Equilibrium dissociation constant (Kd) for ligand–receptor binding

Q7. Which biosensor format is most suitable for detecting a small analyte (hapten) with a single epitope?

  • Sandwich immunosensor
  • Competitive immunosensor
  • Direct fluorescent antibody detection requiring two epitopes
  • Whole-cell reporter sensor

Correct Answer: Competitive immunosensor

Q8. Aptamer-based biosensors (aptasensors) offer which advantage over antibody-based sensors?

  • Higher thermal and chemical stability with synthetic production
  • Always higher affinity than antibodies
  • Require animal immunization for production
  • Can only detect nucleic acids

Correct Answer: Higher thermal and chemical stability with synthetic production

Q9. Which nanoscale material is most commonly used to enhance electron transfer and surface area in electrochemical biosensors?

  • Polystyrene beads
  • Gold nanoparticles and carbon nanotubes
  • Bulk silica plates
  • Glass slides coated with agarose

Correct Answer: Gold nanoparticles and carbon nanotubes

Q10. In a biosensor, limit of detection (LOD) is best described as:

  • The concentration at which the sensor response is maximal
  • The lowest analyte concentration distinguishable from blank with defined confidence
  • The concentration at which the response is no longer linear
  • The time required to reach steady-state signal

Correct Answer: The lowest analyte concentration distinguishable from blank with defined confidence

Q11. Which electrochemical technique measures impedance changes at an electrode caused by biomolecular binding?

  • Chronoamperometry
  • Electrochemical impedance spectroscopy (EIS)
  • UV-Vis absorbance spectroscopy
  • Surface acoustic wave sensing

Correct Answer: Electrochemical impedance spectroscopy (EIS)

Q12. For enzyme electrodes, Michaelis–Menten constant (Km) determination from current–substrate plots provides information about:

  • The electrode surface roughness
  • The apparent substrate affinity of the immobilized enzyme
  • The wavelength of maximum absorbance
  • The mechanical stiffness of the transducer

Correct Answer: The apparent substrate affinity of the immobilized enzyme

Q13. Which biosensor modality directly measures mass changes on a sensor surface with nanogram sensitivity?

  • Surface plasmon resonance
  • Quartz crystal microbalance (QCM)
  • Amperometric electrode
  • Potentiometric ion-selective electrode

Correct Answer: Quartz crystal microbalance (QCM)

Q14. A key benefit of label-free biosensors is:

  • Requirement for complex secondary reagents
  • Ability to monitor binding kinetics in real time without labels
  • Lower specificity compared to labeled assays
  • Inability to detect small molecules

Correct Answer: Ability to monitor binding kinetics in real time without labels

Q15. Which immobilization orientation strategy improves antigen-binding site accessibility in antibody-based sensors?

  • Random physisorption on polystyrene
  • Site-directed immobilization via protein A/G or Fc-specific linkers
  • Entrapment in dense polymer that buries Fab regions
  • Cross-linking via multiple random lysine residues

Correct Answer: Site-directed immobilization via protein A/G or Fc-specific linkers

Q16. In a DNA hybridization biosensor, signal amplification methods often include:

  • Enzyme-mediated catalytic labels, nanoparticle tags or rolling circle amplification
  • Only single-stranded DNA physisorption without amplification
  • Use of bulk protein stains like Coomassie Blue
  • Mechanical stretching of the DNA strands

Correct Answer: Enzyme-mediated catalytic labels, nanoparticle tags or rolling circle amplification

Q17. Which performance characteristic describes how much the output signal changes per unit change in analyte concentration?

  • Specificity
  • Sensitivity
  • Regeneration ability
  • Reproducibility

Correct Answer: Sensitivity

Q18. Whole-cell biosensors are particularly useful for monitoring:

  • Point mutations in single genes with picomolar resolution
  • Biological toxicity, metabolic activity or bioavailability of analytes
  • Only inorganic ion concentrations
  • Surface mass changes without biological response

Correct Answer: Biological toxicity, metabolic activity or bioavailability of analytes

Q19. Which approach improves selectivity of an electrochemical biosensor in complex biological matrices?

  • Ignoring sample pretreatment and measuring directly
  • Incorporating selective membranes, molecularly imprinted polymers or differential measurement strategies
  • Maximizing applied potential without regard to interferents
  • Using a larger electrode area only

Correct Answer: Incorporating selective membranes, molecularly imprinted polymers or differential measurement strategies

Q20. Regeneration of an affinity biosensor surface is typically achieved by:

  • Permanently cross-linking bound analyte to the receptor
  • Applying conditions (pH, ionic strength, chaotropes) that disrupt reversible binding without denaturing the receptor
  • Heating continuously to high temperatures during each measurement
  • Discarding the sensor after a single use only

Correct Answer: Applying conditions (pH, ionic strength, chaotropes) that disrupt reversible binding without denaturing the receptor

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