Q75 Choose the correct match for structural components of bacteria to their function.
| Structural component | Function |
|---|---|
| (P) Flagella | (i) prevent lysis |
| (Q) Cell wall | (ii) chemotaxis |
| (R) Metachromatic granules | (iii) storage for ATP |
| (S) Magnetosomes | (iv) cell orientation |
Correct Answer: Option B (P-ii, Q-i, R-iii, S-iv)
Bacterial structural components perform specific functions essential for survival, motility, and environmental adaptation. This matching question tests knowledge of prokaryotic cell biology, key for CSIR NET Life Sciences preparation.
Component Functions
Flagella (P) enable chemotaxis (ii), allowing bacteria to move toward chemical attractants or away from repellents via rotation powered by proton motive force.
Cell wall (Q) prevents lysis (i) by providing rigid peptidoglycan structure that withstands osmotic pressure in hypotonic environments.
Metachromatic granules (R) serve as storage for ATP (iii), acting as polyphosphate reserves that supply inorganic phosphate for energy metabolism and ATP production.
Magnetosomes (S) facilitate cell orientation (iv) through magnetotaxis, aligning bacteria along magnetic fields via iron crystal chains.
Option Analysis
A (P-ii, Q-iii, R-iv, S-v): Incorrect—flagella match chemotaxis (ii), but cell wall does not do chemotaxis (iii); granules are not for orientation (iv).
B (P-ii, Q-i, R-iii, S-iv): Correct—all matches align with established functions as detailed above.
C (P-iii, Q-ii, R-iv, S-i): Incorrect—flagella enable chemotaxis, not ATP storage (iii); cell wall prevents lysis, not chemotaxis (ii).
D (P-i, Q-iv, R-ii, S-iii): Incorrect—flagella do not prevent lysis (i); granules store phosphate/ATP energy, not strictly ATP alone (though functional).
Bacterial structural components functions play crucial roles in prokaryotic survival, from motility to environmental navigation. Understanding flagella chemotaxis, cell wall protection, metachromatic granules ATP storage, and magnetosomes orientation is vital for CSIR NET Life Sciences aspirants tackling matching questions on bacterial cell biology.
Flagella: Masters of Chemotaxis
Flagella propel bacteria through chemotaxis, sensing chemical gradients to swim toward nutrients or avoid toxins. These whip-like appendages rotate like propellers, driven by basal body motors.
Cell Wall: Barrier Against Lysis
The rigid peptidoglycan cell wall prevents lysis by countering osmotic pressure, maintaining shape and integrity in hypotonic conditions. Lysozyme experiments confirm this protective role.
Metachromatic Granules: ATP and Phosphate Reserves
Metachromatic granules store polyphosphate as energy reserves, supporting ATP synthesis and phosphate needs during stress. They stain distinctly, appearing in phosphate-accumulating bacteria.
Magnetosomes: Magnetic Cell Orientation
Magnetosomes enable magnetotaxis for cell orientation, chaining magnetite crystals to align with Earth’s magnetic field for efficient navigation in sediments.
This knowledge strengthens CSIR NET preparation on bacterial structural components functions.
