This set of Microbiology Multiple Choice Questions & Answers (MCQs) focuses on “Structures External to the Cell Wall”.
1. Bacteria having cluster of flagella at both poles of cells are known as?
Explanation: In amphitrichous, flagella occur either singly or in clusters at both cell poles. Lophotrichous refers to a cluster of polar flagella, peritrichous is surrounded by lateral flagella and monotrichous is for a single polar flagella.
2. Salmonella typhi has which type of flagella arrangement?
Explanation: Salmonella typhi has peritrichous type of flagella arrangement. In peritrichous, the bacteria is surrounded by lateral flagella.
3. The L Ring in a Gram-Negative bacterium flagella is associated with_________
b) Outer Membrane
c) Cytoplasmic Membrane
d) Cell Membrane
Explanation: The flagella in Gram-Negative bacteria has four basal rings. The L Ring of flagella is associated with the outer membrane. The P ring is associated with the peptidoglycan layer and both the M and S rings are associated with the cytoplasmic membrane.
4. Which among the following acts as a transport protein for protons in flagellar motion?
a) fli protein
d) mot protein
Explanation: The proton binds to the Mot protein and this changes the conformation of Mot protein. It results in releasing the ring and helps in flagellar motion. The fli protein helps in changing the direction of flagella.
5. F pilus has a major role as___________
a) motility of the cell
b) port of entry of genetic material during mating
c) attachment to host cell
d) human infection
Explanation: Pili are hollow,filamentous appendages that are thinner and shorter.They do not function in motility and have other different functions.One type known as F plus or sex plus serves as the port of entry of genetic material during bacterial mating.
6. Prosthecae helps in __________
b) nutrient absorption and attachment to surfaces
c) human infection
d) protection from environment
Explanation: Prosthecae increases the surface area of the cells for nutrient absorption, which is advantageous in dilute environments. Some prosthecate bacteria have an adhesive substance at the end of a prostheca that aids in attachment to surfaces.
7. The capsule of Klebsiella pneumoniae is composed of heteropolysaccharides.
Explanation: Heteroploysaccharides are usually synthesized from sugar precursors that are activated within the cell, attached to a lipid carrier molecule, transported across the cytoplasmic membrane and polymerized outside the cell. The capsule of Klebsiella pneumoniae is an example of heteropolysaccharides.
8. When a bacteria swim towards a chemical, it is termed as__________
a) positive chemotaxis
c) negative chemotaxis
Explanation: When a bacteria swims towards or away from chemical compounds, the phenomenon is known as bacterial chemotaxis.Swimming towards a chemical is termed as positive chemotaxis; swimming away is negative chemotaxis.
9. Which type of force drives the flagellar motion?
a) Protonmotive force
b) ATP driven
c) Protonmotive and ATP driven
d) No protonmotive nor ATP driven
Explanation: It is found that flagellar motor is driven by the protonmotive force, i.e., the force derived from the electrical potential and the hydrogen-ion gradient across the cytoplasmic membrane.
Sanfoundry Global Education & Learning Series – Microbiology.
To practice all areas of Microbiology, here is complete set of 1000+ Multiple Choice Questions and Answers.