250+ TOP MCQs on World of Bacteria I – Rickettsias and Chlamydias and Answers

Microbiology Multiple Choice Questions on “World of Bacteria I – Rickettsias and Chlamydias”.

1. Which of the following infect arthropods only?
A. Rickettsieae
B. Ehrlichieae
C. Wolbachieae
D. Rochalimaea
Answer: C
Clarification: The Wolbachieae are not pathogenic for vertebrates, they infect arthropods only.

2. The Rickettsias and Chlamydias are similar in all respects.
A. True
B. False
Answer: B
Clarification: The Rickettsias synthesize ATP as a source of energy whereas Chlamydias cannot synthesize ATP.

3. Classical typhus fever is transmitted by which of the following arthropod?
A. ticks
B. mites
C. fleas
D. lice
Answer: D
Clarification: Classical typhus fever is caused by Rickettsia species and the arthropod vector which transmits the disease is lice.

4.”Growing epicellularly” means ______________
A. on the surface of host cells
B. within the host cell
C. engulfing the host cell
D. damaging the cell membrane of host cell
Answer: A
Clarification: Growing epicellularly means growing on the surface of host cells. Rochalimaea grow epicellularly rather than in the cytoplasm or nucleus.

5. Which of the following genus of Rickettsiaceae have a high resistance to heat?
A. Rickettsia
B. Rochalimaea
C. Coxiella
D. Wolinella
Answer: C
Clarification: The organisms belonging to Coxiella have an unusually high resistance to heat [may survive a temperature of 62 degree C for 30 mins], probably due to the occurrence of endospore-like structures in the cells.

6. C.burnetti causes which of the following diseases?
A. Q fever
B. Trench fever
C. Rocky Mountain spotted fever
D. Typhoid
Answer: A
Clarification: C.burnetti is the causative agent of the Q fever, a type of pneumonia. It belongs to the family Rickettsiaceae.

7. Biting flies occur in which of the following place?
A. Australia
B. North America
C. South America
D. Africa
Answer: C
Clarification: Biting flies occur along the western slopes of the Andes mountains in South America. They transmit Oroya fever in humans.

8. Initial body in the reproduction of Chlamydias is larger than the elementary body.
A. True
B. False
Answer: A
Clarification: Within the vacuole the elementary body is reorganized into a reticulate body known as the initial body, which is two or three times the size of the elementary body and contains a less dense arrangement of nucleoid material.

9. Which is the most prevalent sexually transmitted disease in the US?
A. Syphilis
B. AIDS
C. Lymphogranuloma venerum
D. Nongonococcal urethritis
Answer: D
Clarification: Nongonococcal urethritis is the most prevalent sexually transmitted disease in the United States and is caused by the organisms belonging to the genus Chlamydia.

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