Which of the following diseases is transmitted by the fecal–oral route?

Correct Answer: B

Rationale: The correct answer is B: Peptic ulcer. Peptic ulcers are commonly caused by Helicobacter pylori bacteria, which can be transmitted through the fecal-oral route. This means that the bacteria from infected feces can be ingested through contaminated food or water, leading to the development of peptic ulcers in the gastrointestinal tract. Incorrect choices: A: Ehrlichiosis - Ehrlichiosis is a tick-borne disease transmitted through the bite of an infected tick, not through the fecal-oral route. C: Lyme disease - Lyme disease is also transmitted through the bite of an infected tick, specifically the black-legged tick. D: Tularemia - Tularemia is a bacterial disease typically transmitted through insect bites, handling of infected animals, or ingestion of contaminated water, not through the fecal-oral route.

Correct Answer: A

Rationale: The correct answer is A: Protozoa. Protozoa are eukaryotic microorganisms, meaning they have a true nucleus and membrane-bound organelles. This relates to the question as eukaryotes are organisms with complex cells containing these features. Viruses (B) are non-living entities that require a host cell to replicate, lacking cellular structures. Viroids (C) are smaller than viruses and consist of only RNA, lacking a protein coat. Prions (D) are misfolded proteins causing diseases but are not considered microorganisms nor do they have cellular structure. Thus, protozoa are the only eukaryotic microorganism group among the options.

Correct Answer: C

Rationale: The correct answer is C: Adhesion and immune evasion. Bacterial capsules serve as a protective layer that aids in adhesion to surfaces and host cells, allowing bacteria to colonize and evade the immune system. This function is crucial for bacterial survival and pathogenicity. Choices A and D are incorrect because energy production and DNA replication are not primary functions of bacterial capsules. Choice B is incorrect because while bacterial capsules do provide some protection from desiccation, their primary function lies in adhesion and immune evasion.

Correct Answer: A

Rationale: The correct answer is A: cytomegalovirus. CMV is the most common virus transmitted during pregnancy, leading to potential serious complications for the fetus. It can cause birth defects, hearing loss, and developmental delays. CMV is commonly spread through bodily fluids. HIV (B) can also be transmitted during pregnancy but is less common. Herpes simplex virus (C) can be transmitted but typically results in localized infection. Epstein-Barr virus (D) is not commonly transmitted during pregnancy.

Correct Answer: A

Rationale: The correct answer is A: Halogens. Chlorine belongs to the halogens group because it is a nonmetal element in group 17 of the periodic table. Halogens are highly reactive elements that have 7 electrons in their outer shell, making them eager to gain an electron to achieve stability. Chlorine specifically is a diatomic molecule with the chemical symbol Cl and atomic number 17. Option B: Heavy metals are elements with high atomic weights and densities, such as lead and mercury, which are not related to chlorine. Option C: Phenols are a class of organic compounds containing a hydroxyl group bonded to an aromatic ring, not related to chlorine. Option D: Alcohols are organic compounds characterized by the presence of a hydroxyl group (-OH), also not related to chlorine.

Correct Answer: C

Rationale: The correct answer is C: Anti-measles IgM. During acute measles infection, the body produces IgM antibodies specific to the measles virus. This indicates a recent or current infection. A: Anti-mumps IgM and B: Anti-rubella IgM are specific to mumps and rubella viruses, respectively, not measles. D: Anti-CMV IgM is specific to cytomegalovirus, not measles. In summary, choice C is correct because Anti-measles IgM is the specific antibody indicating acute measles infection, while the other choices are antibodies related to different viruses.

Correct Answer: B

Rationale: Step 1: Adenoviruses are known to have icosahedral capsids, not helical. Step 2: Helical capsids are typically found in viruses like tobacco mosaic virus. Step 3: Therefore, the statement that adenoviruses have helical capsids is FALSE. Summary: A is incorrect as adenoviruses do not have helical capsids. C is incorrect as there is no situation where adenoviruses have helical capsids. D is incorrect as there is a clear correct answer, which is B.

Correct Answer: C

Rationale: The correct answer is C: Spleen. The white pulp of the spleen contains lymphocytes that help in immune responses. The red pulp filters blood and removes old or damaged red blood cells. The thymus (A) is responsible for T cell maturation, lymph nodes (B) filter lymph, and lymphoid tissue (D) includes various lymphoid organs but does not specifically refer to the spleen's distinct white and red pulp structure. Thus, the spleen is the only organ among the choices that has both white and red pulp components essential for immune functions.

Correct Answer: A

Rationale: The correct answer is A: Tryptic soy agar is a general-purpose medium suitable for cultivating a wide range of microorganisms. It provides essential nutrients for growth without inhibiting specific types of bacteria. Blood agar (B), Mannitol salt agar (C), and MacConkey agar (D) are selective or differential media designed to promote the growth of specific types of bacteria or differentiate between different bacterial species. Therefore, they are not considered general-purpose mediums.