Lytic life cycle of phages does not include

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.

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.

Correct Answer: A

Rationale: The correct answer is A: Neutralization. In this scenario, the antibotulinic serum of types A, B, and E were introduced to neutralize the botulinum toxin in the test specimen. The serological reaction applied here involves the neutralization of the toxin by the specific antibodies present in the serum. This process prevents the toxin from causing harm to the mice. Summary of other choices: B: Precipitation - This involves the formation of insoluble complexes between antigen and antibody, not the specific neutralization seen in this case. C: Complement binding - This involves activation of the complement system leading to cell lysis, not the direct neutralization of toxin. D: Double immune diffusion - This technique is used to determine the presence of specific antibodies or antigens based on their diffusion patterns, not the neutralization of toxin as seen in this scenario.

Correct Answer: A

Rationale: The correct answer is A: yeast and molds. Yeast and molds can resist acidic pH due to their ability to maintain a stable internal pH through various mechanisms such as ion transport and cell wall composition. Bacteria, including E. coli, are generally more sensitive to acidic conditions. Choice D is incorrect as yeast and molds are known to thrive in acidic environments.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Clostridium botulinum causes botulism, Salmonella enterica causes salmonellosis, and Escherichia coli can cause foodborne illnesses such as E. coli infection. All three bacteria are associated with foodborne illnesses due to contamination of food or water sources. Therefore, selecting "All of the above" is the most appropriate choice as it includes all the bacteria commonly linked to foodborne illnesses. The other choices (A, B, and C) are incorrect because they do not encompass all the bacteria associated with foodborne illnesses as stated above.

Correct Answer: A

Rationale: The most probable diagnosis is A: Candidous cheilitis. Candidous cheilitis is a fungal infection caused by Candida species. In this case, the presence of mycelium on the plaques indicates a fungal infection. The symptoms of pain, burning, and grey plaques that can be easily removed leaving hyperemia are typical for Candidous cheilitis. Choice B (Exfoliative cheilitis) is characterized by scaling and peeling of the lips, not plaques with mycelium. Choice C (Leukoplakia) is a precancerous condition causing white plaques that cannot be easily removed. Choice D (Contactant allergic cheilitis) is an allergic reaction causing inflammation, not fungal plaques.

Correct Answer: A

Rationale: The correct answer is A: Toxoplasmosis. Toxoplasmosis is a parasitic infection caused by Toxoplasma gondii, which can be transmitted from mother to fetus during pregnancy, leading to congenital toxoplasmosis. This infection can result in stillbirth, multiple developmental defects, and intrauterine death. Leishmaniasis (B), Malaria (C), and Amebiasis (D) are caused by different parasites and do not typically lead to intrauterine death or developmental defects in the fetus.

Correct Answer: A

Rationale: Step-by-step rationale: 1. IgG is the most abundant immunoglobin in a normal healthy adult due to its long half-life and diverse functions. 2. It plays a crucial role in immune response by neutralizing pathogens and enhancing phagocytosis. 3. IgA is mainly found in mucosal areas, IgE is involved in allergic reactions, and IgD's function is not fully understood. 4. Therefore, IgG is the correct answer as it is the predominant immunoglobin in circulation, providing broad immune protection.

Correct Answer: C

Rationale: Step 1: "Fried egg" colonies typically refer to colonies with a raised center and flattened periphery, resembling the appearance of a fried egg. Step 2: Actinomycetes are filamentous bacteria known to form "fried egg" colonies in nutrient medium. Step 3: Actinomycetes are commonly found in soil and are known to be phytopathogenic microorganisms. Step 4: Actinomycetes produce secondary metabolites with medicinal properties, making them a likely agent from a medicinal herb. Overall, the correct answer is C (Actinomycetes) as they fit the description provided in the question and are commonly associated with the given scenario. The other choices are incorrect as they do not exhibit the specific characteristics mentioned in the question or are not typically associated with forming "fried egg" colonies in nutrient medium.