Q.21 Match the type of bacterial flagella in Group I with their definitions in Group II
Group I Group II
(P) Monotrichous (1) Flagella only at both poles of the cell
(Q) Peritrichous (2) Two or more flagella at one pole of the cell
(R) Lophotrichous (3) Flagella distributed over the entire cell
(S) Amphitrichous (4) A single polar flagellum
(A) P-4, Q-1, R-2, S-3
(B) P-4, Q-3, R-2, S-1
(C) P-4, Q-3, R-1, S-2
(D) P-3, Q-1, R-4, S-2
The correct answer is (B) P-4, Q-3, R-2, S-1.
Bacterial flagella arrangements classify motility patterns essential for CSIR NET Life Sciences. Group I terms match Group II definitions as follows: Monotrichous (P) aligns with a single polar flagellum (4), peritrichous (Q) with flagella over the entire cell (3), lophotrichous (R) with two or more at one pole (2), and amphitrichous (S) with flagella at both poles (1).
Option Analysis
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(A) P-4, Q-1, R-2, S-3: Incorrect. Q (peritrichous) mismatches 1 (both poles, amphitrichous trait); S (amphitrichous) mismatches 3 (entire cell, peritrichous trait).
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(B) P-4, Q-3, R-2, S-1: Correct. Matches standard definitions: P as single polar (4), Q as entire surface (3), R as multiple at one pole (2), S as both poles (1). Examples include Vibrio cholerae (monotrichous) and E. coli (peritrichous).
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(C) P-4, Q-3, R-1, S-2: Incorrect. R (lophotrichous) mismatches 1 (both poles); S mismatches 2 (one pole multiple).
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(D) P-3, Q-1, R-4, S-2: Incorrect. P mismatches 3 (not entire cell); multiple mismatches follow.
Flagella Arrangements Table
| Type (Group I) | Definition (Group II) | Examples |
|---|---|---|
| P: Monotrichous | 4: Single polar flagellum | Vibrio cholerae |
| Q: Peritrichous | 3: Entire cell | E. coli, Salmonella |
| R: Lophotrichous | 2: Two or more at one pole | Pseudomonas fluorescens |
| S: Amphitrichous | 1: Both poles | Alkaligenes faecalis |
Bacterial flagella types matching questions test microbiology fundamentals for CSIR NET aspirants, focusing on arrangements like monotrichous, peritrichous, lophotrichous, and amphitrichous. These motility structures enable bacterial navigation via rotation, crucial for pathogenesis and survival.
Understanding definitions prevents common errors: monotrichous features one polar flagellum for straightforward propulsion, while peritrichous covers the whole surface for omnidirectional “run-and-tumble” motion.
Lophotrichous tufts at one pole bundle for thrust, as in Pseudomonas, and amphitrichous flagella at both poles allow reversals, seen in Spirillum. This knowledge aids Unit 1 (Cellular Organization) exam prep.
