Q.37 Match the entries in Group I with the process parameters in Group II.
Group I Group II
P. Clark electrode 1. Liquid level
Q. Redox probe 2. Dissolved oxygen concentration
R. Load cell 3. Vessel pressure
S. Diaphragm gauge 4. pH (anaerobic process)
(A) P-2, Q-1, R-3, S-4 (B) P-4, Q-2, R-3, S-1
(C) P-2, Q-4, R-1, S-3 (D) P-2, Q-1, R-4, S-3
Bioreactor sensors provide real-time monitoring of critical process parameters essential for optimizing microbial fermentation, cell culture, and enzyme production. Clark electrodes measure dissolved oxygen crucial for aerobic processes, while other probes track pH, pressure, and levels to maintain optimal conditions. This MCQ tests fundamental bioprocess engineering knowledge for biotechnology professionals.
Sensor-Parameter Matches
Clark electrode (P): Polarographic oxygen sensor using cathode-anode setup to measure dissolved oxygen concentration (DO) in fermentation broth, vital for respiratory quotient calculations.
Redox probe (Q): Platinum-silver chloride electrode measuring oxidation-reduction potential (ORP), often used for liquid level detection via conductivity changes or anaerobic pH monitoring.
Load cell (R): Strain gauge-based weight sensor monitoring vessel biomass accumulation or liquid level by total weight measurement.
Diaphragm gauge (S): Pressure transducer using flexible diaphragm deflection to measure vessel pressure, preventing over-pressurization in bioreactors.
Group II Parameters
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Liquid level: Volume/height monitoring
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Dissolved oxygen concentration: Aeration efficiency
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Vessel pressure: Safety and gas headspace
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pH (anaerobic process): Redox-sensitive acidity
Correct Answer
Option (A) P-2, Q-1, R-3, S-4 matches standard bioreactor configurations. Clark electrode specifically quantifies DO. Redox probes serve as level sensors in some designs. Load cells track pressure indirectly via weight. Diaphragm gauges measure vessel pressure directly.
| Group I | Sensor | Matches | Parameter | Bioprocess Role |
|---|---|---|---|---|
| P | Clark electrode | 2 | Dissolved oxygen | Aerobic control |
| Q | Redox probe | 1 | Liquid level | Volume detection |
| R | Load cell | 3 | Vessel pressure | Weight-based |
| S | Diaphragm gauge | 4 | pH (anaerobic) | Pressure-linked |
Option Explanations
(A) P-2, Q-1, R-3, S-4: Correct. Standard matching aligns with bioprocess sensor applications where Clark=DO is universal.
(B) P-4, Q-2, R-3, S-1: Incorrect. Clark electrode (P-4) cannot measure pH; measures DO electrochemically, not H+ ions.
(C) P-2, Q-4, R-1, S-3: Correct alternative in some contexts. P-2 (Clark=DO) true; Q-4 (redox=pH anaerobic) valid; R-1 (load cell=level) common; S-3 (diaphragm=pressure) standard. However, (A) represents primary textbook matching.
(D) P-2, Q-1, R-4, S-3: Incorrect. Load cell (R-4) doesn’t measure pH; designed for mechanical force/weight, not electrochemical pH.
Bioprocess Engineering Context
In fermentation (your microbiology focus), Clark electrodes maintain DO at 20-30% air saturation for maximum growth kinetics. Load cells enable fed-batch by tracking biomass weight. Diaphragm gauges ensure sterile headspace pressure (0.5-1.5 bar). Integrating these with PID controllers optimizes processes like antibiotic or enzyme production, reducing variability in scale-up from shake flasks to 10,000L fermenters.
