Nokea
Lytic life cycle of phages does not include
- A. germination
- B. penetration
- C. adsorption
- D. lysis
Correct Answer: A
Rationale: The correct answer is A: germination. In the lytic life cycle of phages, germination is not a stage. The lytic cycle involves adsorption, penetration, replication, assembly, and lysis. Germination is typically associated with the lysogenic cycle, where the phage DNA integrates into the host genome. Therefore, A is the correct answer. Choices B, C, and D are incorrect because they are all stages of the lytic cycle. Penetration refers to the injection of phage DNA into the host cell, adsorption is the attachment of the phage to the host cell, and lysis is the final stage where the host cell bursts, releasing new phages.
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Which of the following best describes the function of bacterial capsules?
- A. Enhance bacterial motility
- B. Enable bacterial adherence to surfaces
- C. Prevent bacterial DNA replication
- D. Protect bacteria from desiccation
Correct Answer: B
Rationale: The correct answer is B: Enable bacterial adherence to surfaces. Bacterial capsules are a protective layer outside the cell wall that helps bacteria adhere to surfaces and evade host immune responses. This allows bacteria to colonize and infect host tissues.
A: Enhancing bacterial motility is typically associated with flagella, not capsules.
C: Bacterial DNA replication is not directly affected by capsules.
D: Bacterial capsules do play a role in protecting bacteria from desiccation by providing a barrier against drying out. However, the primary function is enabling adherence to surfaces.
How the prepared immunofluorescence slide should be examined?
- A. Under the fluorescence microscope using x100 oil immersion objective
- B. Under light microscope using x100 oil immersion objective
- C. Using electron microscopy
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because immunofluorescence slides are examined under a fluorescence microscope with a x100 oil immersion objective. This is because immunofluorescence relies on the detection of fluorescently labeled antibodies, which emit light when excited by a specific wavelength. Using a fluorescence microscope allows for visualization of these labeled antibodies at high magnification and resolution, enabling precise examination of cellular structures and protein localization. Choice B is incorrect as light microscopes are not suitable for visualizing fluorescence. Choice C is incorrect as electron microscopes use electrons, not light, for imaging, which is not compatible with immunofluorescence. Choice D is incorrect as there is a specific method for examining immunofluorescence slides.
The Marburg virus was originally spread by:
- A. laboratory rats
- B. birds
- C. green monkeys
- D. wild turkeys
Correct Answer: C
Rationale: The correct answer is C: green monkeys. The Marburg virus was first identified in 1967 in Marburg and Frankfurt, Germany, after outbreaks in lab workers exposed to infected African green monkeys. These monkeys were imported from Uganda. The virus is believed to be originally endemic in certain species of African bats and is transmitted to humans through contact with infected animals. Choice A, laboratory rats, is incorrect as the virus did not originate from rats. Choice B, birds, and Choice D, wild turkeys, are also incorrect as there is no evidence linking these animals to the transmission of the Marburg virus.
N. Meningitidis grows on
- A. Levine agar
- B. Lowenstein-Jensen agar
- C. TCBS agar
- D. Chocolate agar
Correct Answer: D
Rationale: The correct answer is D: Chocolate agar. Neisseria meningitidis is a fastidious organism that requires enriched media for growth. Chocolate agar contains heat-treated blood that provides essential nutrients for the growth of N. meningitidis. The other choices, A: Levine agar, B: Lowenstein-Jensen agar, and C: TCBS agar, do not provide the specific nutrients required for the growth of N. meningitidis. Therefore, only choice D, Chocolate agar, supports the growth of N. meningitidis due to its enriched composition.
Malaria is caused by a:
- A. virus
- B. bacterium
- C. helminth
- D. protozoan
Correct Answer: D
Rationale: The correct answer is D: protozoan. Malaria is caused by Plasmodium parasites transmitted through the bite of infected female Anopheles mosquitoes. These parasites belong to the protozoa kingdom, not viruses (choice A), bacteria (choice B), or helminths (choice C). Protozoa have complex life cycles involving both mosquito and human hosts, leading to the development of malaria in humans. Other choices are incorrect as they do not align with the known etiology and characteristics of malaria.