Section 4: Bioprocess Engineering and Process Biotechnology
Bioreactor types, scale-up
Subtopic: Fundamentals of Bioreactor types, scale-up
Question Statement:
The diversity in T-cell receptors is generated by
Options:
(A) gene rearrangements
(B) somatic hypermutation of rearranged V region
(C) gene conversion
(D) class switching
Official Answer Key:
A
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2025 Q.15)**
**1. Governing Concept**:
- **Topic**: Bioprocess Engineering & Dimensional Analysis / Dimensionless Numbers
- Dimensionless groups in fluid mechanics and transport phenomena:
- **Reynolds Number ($Re = \frac{\rho v D}{\mu}$)**: Ratio of inertial forces to viscous forces.
- **Schmidt Number ($Sc = \frac{\mu}{\rho D_{AB}}$)**: Ratio of momentum diffusivity (kinematic viscosity $\nu$) to mass diffusivity.
- **Prandtl Number ($Pr = \frac{C_p \mu}{k}$)**: Ratio of momentum diffusivity to thermal diffusivity.
- **Sherwood Number ($Sh = \frac{k_L D}{D_{AB}}$)**: Ratio of convective mass transfer to diffusive mass transport.
**2. Option Analysis**:
- **Option (A) is INCORRECT**: Defines Prandtl number, which governs heat transfer.
- **Option (B) is CORRECT**: Schmidt number ($Sc$) is the ratio of momentum diffusivity ($\nu = \mu/\rho$) to molecular mass diffusivity ($D_{AB}$).
- **Option (C) is INCORRECT**: Defines Reynolds number.
- **Option (D) is INCORRECT**: Defines Peclet number.
**3. Final Answer**:
- **Correct Choice**: **B**
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