Section 4: Bioprocess Engineering and Process Biotechnology
Bioreactor types, scale-up
Subtopic: Fundamentals of Bioreactor types, scale-up
Question Statement:
Which of the following conditions will contribute to the stability of a gene pool
in a natural population?
P. Large population
Q. No net mutation
R. Non-random mating
S. No selection
Options:
(A) E1 and E2 only
(B) E1 and E3 only
(C) E1 and E4 only
(D) E1, E2 and E3
Official Answer Key:
D
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2022 Q.36)**
**1. Governing Concept**:
- **Topic**: Bioprocess Fluid Dynamics & Aerobic Fermentation
- In a sparged stirred tank bioreactor:
- The volumetric oxygen mass transfer coefficient $k_L a$ is governed by empirical correlations:
$k_L a = k \left(\frac{P_g}{V}\right)^\alpha v_s^\beta$
- Increasing impeller agitation speed ($N$) and gas superficial velocity ($v_s$) reduces bubble diameter, increases gas holdup, and enhances turbulence, thereby increasing interfacial area $a$ and mass transfer coefficient $k_L$.
- High medium viscosity or addition of certain surface-active antifoam agents reduces bubble coalescence but can decrease $k_L a$.
**2. Option Analysis**:
- **Option (A) is INCORRECT**: Opposite effect on gas-liquid mass transfer.
- **Option (B) is INCORRECT**: Contradicted by mass transfer correlations.
- **Option (C) is INCORRECT**: Antifoam typically suppresses $k_L a$ rather than enhancing it.
- **Option (D) is CORRECT**: Accurately describes operating conditions that maximize oxygen transfer rate.
**3. Final Answer**:
- **Correct Choice**: **D**
Practice This in Real CBT Exam Interface
Test yourself with the official TCS-iON palette, virtual calculator, and immediate performance analytics.