This set of Microbiology Multiple Choice Questions & Answers (MCQs) focuses on “World of Bacteria I – Spirochetes”.
1. The endoflagella is present in which class of bacteria?
a) Spirilla
b) Spirochetes
c) Bacillus
d) Coccus
View Answer
Explanation: Spirochetes have an ability to twist or contort their shape due to the occurrence of a special kind of flagella termed periplasmic flagella or endoflagella.
2. Where is the endoflagella located in Spirochetes?
a) In the cell membrane
b) In the cytoplasm
c) In the peptidoglycan layer
d) In the periplasmic space
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Explanation: In spirochetes, the endoflagella or as it is called periplasmic flagella is located between the outer membrane and the protoplasmic cylinder; thus they are located in the periplasmic space of the cell.
3. Spirochetes like other bacteria swim best in media of low viscosity.
a) True
b) False
View Answer
Explanation: Spirochetes because of the added advantage of having an endoflagella swims best in media of high viscosity, whereas bacteria with ordinary flagella swim best in media of low viscosity.
4. Which of the following methods is used for viewing spirochetes?
a) Bright-field microscopy
b) Phase-contrast microscopy
c) Dark-field microscopy
d) Electron microscopy
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Explanation: Most spirochetes are so thin that they cannot be easily seen by light microscopy, even when Gram-stained; however, dark-field microscopy does provide sufficient contrast and is the method of choice for visualizing these organisms.
5. The family Leptospiraceae are aerobes.
a) True
b) False
View Answer
Explanation: The family Leptospiraceae of spirochetes are aerobes who use long-chain fatty acids as the carbon and energy source.
6. Which among the following are microaerophilic bacteria?
a) Spirochaeta
b) Cristispira
c) Treponema
d) Borrelia
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Explanation: Borrelia is the genus of bacteria belonging to the class Spirochaetaceae and are microaerophilic.
7. Which of the following bacteria causes syphilis in humans?
a) Treponema dysenteriae
b) Treponema pallidum
c) Leptospira biflexa
d) Leptospira interrogans
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Explanation: Treponema pallidum causes syphilis in humans and is microaerophilic. They belong to the family Spirochaetaceae and are found in the mouth, intestinal tract, and genital areas of humans and animals.
8. Which of the following have bipolar tufts of flagella?
a) Aquaspirillum
b) Azospirillum
c) Cristispira
d) Borrelia
View Answer
Explanation: Aquaspirilla are helical or vibroid organisms that typically possess bipolar tufts of flagella. They may be aerobic or microaerophilic and occur in a stagnant stream or pond water.
9. Which of the following causes diarrhea in humans?
a) A.lipoferum
b) L.interrogans
c) C.jejuni
d) E.coli
View Answer
Explanation: C.jejuni causes diarrhea in humans and belong to the genus Campylobacters. They are microaerophilic parasites and occur in the reproductive organs, intestinal tract, and oral cavity of humans and other mammals.
10. Which genus among the following has certain similarities to the genus Bdellovibrio?
a) Azospirillum
b) Oceanospirillum
c) Campylobacter
d) Vamprirovibrio
View Answer
Explanation: The genus Vampirovibrio has certain similarities to the genus Bdellovibrio, but the organisms attack eukaryotic algae, not bacteria.
11. Which group of bacteria among the following give a positive reaction by the oxidase test?
a) Spirochetes
b) Aerobic/Microaerophilic, Motile, Helical/Vibroid, Gram-negative bacteria
c) Non-motile, Gram-negative, Curved bacteria
d) Aerobic, Gram-negative rods and cocci
View Answer
Explanation: Aerobic/Microaerophilic, motile, Helical/Vibroid, Gram-negative bacteria are organisms that usually give a positive reaction by the oxidase test. It is a laboratory test based on the presence of cytochrome c.
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