Correct Answer: A

Rationale: Step 1: Oval, round, elongated chains of gemmating cells indicate yeast-like budding cells seen in Candida species. Step 2: Candidosis is caused by Candida species, which is commonly found in the oral cavity and can cause infections on the tongue. Step 3: Candidosis presents as white patches or plaques on the tongue. Step 4: Therefore, the correct answer is A: Candidosis. Summary: B: Actinomycosis is caused by Actinomyces species, which are filamentous bacteria, not oval budding cells. C: Diphtheria is caused by Corynebacterium diphtheriae, which appears as gram-positive rods in chains, not oval budding cells. D: Staphylococcal infections are caused by Staphylococcus species, which appear as clusters of cocci, not oval budding cells.

Correct Answer: D

Rationale: Step 1: Micellar growth refers to the apical prolongation of hyphae in fungi. Step 2: Fungi have a unique growth structure with hyphae extending at the tips. Step 3: This growth pattern allows fungi to expand and access nutrients. Step 4: Bacterial cells (A) do not exhibit micellar growth. Step 5: Parent and daughter cells in division have similar sizes, not different (B). Step 6: Viruses and rickettsia (C) do not display micellar growth.

Correct Answer: D

Rationale: The correct answer is D because all three bacteria listed are capable of producing exotoxins that can cause severe diarrhea. Escherichia coli can produce toxins that lead to diarrhea. Clostridium botulinum produces a neurotoxin causing botulism, which can also result in diarrhea. Vibrio cholerae is known for producing cholera toxin, a potent exotoxin that causes severe watery diarrhea. The other choices are incorrect because each bacterium listed is capable of producing a toxin that can cause diarrhea.

Correct Answer: B

Rationale: The correct answer is B: sporadic disease. Infection of several persons without any epidemiological link is considered sporadic because it occurs in a random and isolated manner, with no clear pattern or connection between cases. It is not classified as an epidemic (A) because it does not involve a sudden increase in the number of cases within a specific population. It is also not endemic (C) as endemic diseases are constantly present in a particular region or population. Lastly, it is not a pandemic (D) which refers to a global outbreak affecting a large number of people across different countries.

Correct Answer: B

Rationale: The correct answer is B: Treponema pallidum. The scenario describes symptoms of primary syphilis, which is caused by Treponema pallidum. The presence of a painless ulcer (chancre) and enlarged inguinal lymph nodes are characteristic of syphilis. Dark field microscopic examination showing motile, curved spirochetes is highly specific for Treponema pallidum. Incorrect explanations: A: Chlamydia trachomatis typically causes urethritis or cervicitis, not painless ulcers. C: Neisseria gonorrhoeae causes gonorrhea, which presents with purulent discharge, not painless ulcers. D: Herpes simplex virus type 2 causes genital herpes, leading to painful ulcers and vesicles, not painless ulcers seen in syphilis.