Nokea
Which of the following bacteria is responsible for causing the plague?
- A. Yersinia pestis
- B. Clostridium difficile
- C. Neisseria gonorrhoeae
- D. Pseudomonas aeruginosa
Correct Answer: A
Rationale: The correct answer is A: Yersinia pestis. Y. pestis is responsible for causing the plague, a severe infectious disease. This bacterium is transmitted via fleas from rodents to humans. It causes bubonic, septicemic, and pneumonic plague. Clostridium difficile causes gastrointestinal infections, Neisseria gonorrhoeae causes gonorrhea, and Pseudomonas aeruginosa can cause various infections but not the plague.
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Babesiosis is a vector-borne, malaria-like illness caused by a:
- A. bacterium
- B. virus
- C. helminth
- D. protozoan
Correct Answer: D
Rationale: The correct answer is D: protozoan. Babesiosis is caused by a protozoan parasite called Babesia. Protozoans are single-celled organisms that can cause various diseases in humans. Babesiosis is transmitted to humans through the bite of infected ticks. Bacteria (choice A), viruses (choice B), and helminths (choice C) are not responsible for causing babesiosis. Bacteria are typically responsible for diseases like Lyme disease, viruses for illnesses like Zika, and helminths for infections such as parasitic worms. Thus, the correct choice for the causative agent of babesiosis is a protozoan.
Bacteria that grow in the absence of oxygen are called:
- A. Obligate aerobes
- B. Facultative anaerobes
- C. Obligate anaerobes
- D. Aerotolerant anaerobes
Correct Answer: C
Rationale: The correct answer is C: Obligate anaerobes. These bacteria cannot survive in the presence of oxygen as they lack the necessary enzymes to detoxify reactive oxygen species. Obligate aerobes (A) require oxygen, facultative anaerobes (B) can grow with or without oxygen, and aerotolerant anaerobes (D) can survive in the presence of oxygen but do not utilize it for growth.
The distinctive pattern of adenoviruses is due to;
- A. Lipid envelope
- B. Helical capsid
- C. ssDNA
- D. Fibers at the vertices of the icosahedron
Correct Answer: D
Rationale: The correct answer is D: Fibers at the vertices of the icosahedron. Adenoviruses have fibers at the vertices of the icosahedron, which give them their distinctive pattern. These fibers help in attaching to host cells. Choices A, B, and C are incorrect because adenoviruses do not have a lipid envelope, helical capsid, or ssDNA. Adenoviruses have a non-enveloped icosahedral capsid and contain dsDNA. This makes choice D the correct answer as it specifically relates to the unique structural feature of adenoviruses.
During examination of the patient's oral cavity a dentist noticed deformation of the teeth and a crescent indentation of the upper right incisor. The teeth are undersized, barrel-shaped – tooth cervix is wider than its edge. The patient uses a hearing aid, suffers from visual impairment. What type of syphilis affects teeth in such way?
- A. Primary
- B. Early congenital
- C. Neurosyphilis
- D. Late congenital
Correct Answer: D
Rationale: The correct answer is D, Late congenital syphilis. This is because the patient presents with Hutchinson's teeth, which are a characteristic feature of late congenital syphilis. Hutchinson's teeth are small, barrel-shaped teeth with a wider cervix and notched incisors. The patient's history of visual impairment and hearing aid use also support the diagnosis of late congenital syphilis, as these are common manifestations of this stage of the disease.
Choice A, Primary syphilis, is incorrect because it typically presents with a painless sore at the site of infection, not dental abnormalities. Choice B, Early congenital syphilis, is incorrect as dental abnormalities in this stage are usually more severe, such as mulberry molars. Choice C, Neurosyphilis, is incorrect as it primarily affects the central nervous system and does not typically present with dental abnormalities.
Lytic cycle of the bacteriophages differs from the lysogenic one by
- A. lysogenetic phages destroy the host cell when leaving the cell
- B. lytic phages do not destroy the host cell
- C. do not differ
- D. none of them
Correct Answer: A
Rationale: The correct answer is A because in the lytic cycle, the bacteriophage destroys the host cell upon release, whereas in the lysogenic cycle, the phage integrates its DNA into the host genome without killing the host immediately. This integration may lead to the destruction of the host cell at a later stage. Choice B is incorrect as lytic phages do destroy the host cell. Choice C is incorrect as the two cycles have distinct mechanisms. Choice D is incorrect as there are clear differences between the lytic and lysogenic cycles.