Section 4: Bioprocess Engineering and Process Biotechnology
Mass transfer in bioprocesses (kLa)
Subtopic: Fundamentals of Mass transfer in bioprocesses (kLa)
Question Statement:
Bacteria with two or more flagella at one or both ends are called
Options:
(A) the addition of switch region nucleotides
(B) the addition of N and P nucleotides
(C) the joining of V, D and J segments
(D) mutations in complementarity-determining regions
Official Answer Key:
C
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2016 Q.11)**
**1. Governing Concept & Question Classification**:
- **Section**: BT
- **Question Type**: **MCQ** (1 Mark)
- **Topic**: Microbiology (Bacterial Flagellar Arrangements & Morphology)
**2. Detailed Step-by-Step Analysis**:
- Bacterial flagellar arrangements are classified into four classical morphological types:
1. **Monotrichous**: A single polar flagellum at one end (e.g., *Vibrio cholerae*, *Pseudomonas aeruginosa*).
2. **Lophotrichous**: A cluster or tuft of two or more flagella at one or both ends of the bacterial cell (e.g., *Spirillum*, *Pseudomonas fluorescens*).
3. **Amphitrichous**: A single flagellum at each of the two opposite poles.
4. **Peritrichous**: Flagella distributed uniformly over the entire surface of the cell (e.g., *Escherichia coli*, *Proteus vulgaris*).
5. **Atrichous**: Bacteria completely lacking flagella (e.g., *Klebsiella pneumoniae*).
- The question describes: *“Bacteria with two or more flagella at one or both ends”*.
- This directly matches the definition of **lophotrichous**.
- **Option-by-Option Evaluation**:
- **Option (A) [INCORRECT]**: Amphitrichous refers to a single flagellum at each opposite end.
- **Option (B) [INCORRECT]**: Peritrichous refers to flagella distributed all over the cell surface.
- **Option (C) [CORRECT]**: Lophotrichous bacteria possess a tuft of two or more flagella at one or both poles.
- **Option (D) [INCORRECT]**: Atrichous describes non-flagellated bacteria.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **C**
- **Scoring Criteria**: +1.0 Mark (Negative marking: -0.33 marks).
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