What comes after class in the classification system?

Correct Answer: B

Rationale: The correct answer is B: Phylum. After class in the classification system comes phylum. The classification system starts with the broadest category, which is the kingdom, followed by phylum, class, order, family, genus, and species. Phylum is a higher level of classification than class, so it comes next in the hierarchy. Domain is a higher level than kingdom, and order is a lower level of classification than class. Therefore, the correct sequence is kingdom, phylum, class, order.

Correct Answer: B

Rationale: The main function of bacterial pili is to facilitate conjugation and adhesion. Pili are hair-like appendages on bacteria that help in cell-to-cell interactions. They play a crucial role in bacterial conjugation by allowing the transfer of genetic material between cells. Additionally, pili help bacteria adhere to surfaces or host cells, aiding in colonization and biofilm formation. Choices A and D are incorrect because protein synthesis and toxin secretion are not the primary functions of pili. Choice C is incorrect as bacterial motility is mainly mediated by flagella, not pili.

Correct Answer: D

Rationale: The correct answer is D: Oral candidiasis. Soor is a term used to describe oral candidiasis, a fungal infection caused by Candida species. This infection presents as white patches on the tongue, inner cheeks, and roof of the mouth. The other choices (A, B, C) refer to different types of fungal infections affecting various parts of the body, not specifically the oral cavity. Therefore, based on the description of soor and its characteristics, the correct answer is D.

Correct Answer: C

Rationale: The correct answer is C: Negative stain. Negative staining uses acidic dyes which are repelled by the bacterial cell wall components, highlighting bacteria with a large amount of peptidoglycan. Acid-fast stain (A) is used to identify Mycobacterium species with waxy cell walls. Gram stain (B) differentiates bacteria into Gram-positive and Gram-negative based on cell wall composition. Option D is a duplicate of option C and is incorrect.

Correct Answer: A

Rationale: Rationale: 1. Epstein-Barr virus causes infectious mononucleosis due to primary infection. 2. Certain types of cancer, such as Burkitt lymphoma and nasopharyngeal carcinoma, are associated with Epstein-Barr virus through oncogenic mechanisms. 3. Chickenpox and shingles are caused by varicella-zoster virus (HHV3). 4. Roseola infantum is caused by human herpesvirus 6 (HHV6). Summary: Choice A is correct as Epstein-Barr virus is linked to infectious mononucleosis and specific cancers. Choices B, C, and D are incorrect as they are caused by different herpesviruses.

Correct Answer: D

Rationale: The correct answer is D: rabbit fever. Tularemia is commonly known as rabbit fever due to the fact that it is often contracted through handling infected rabbits or other rodents. This zoonotic disease is caused by the bacterium Francisella tularensis. Scarlet fever (A) is a streptococcal infection characterized by a rash, not related to tularemia. Strep throat (B) is a bacterial infection caused by Streptococcus bacteria and is not associated with tularemia. Cat scratch fever (C) is caused by Bartonella henselae and typically transmitted through cat scratches or bites, not related to tularemia.

Correct Answer: D

Rationale: The correct answer is D (All of the above) as all three bacteria (Escherichia coli, Salmonella enterica, Neisseria meningitidis) produce endotoxins causing fever and shock. Endotoxins are lipopolysaccharides found in the outer membrane of Gram-negative bacteria and can trigger an immune response leading to fever and shock. Escherichia coli and Salmonella enterica are common causes of food poisoning and sepsis, while Neisseria meningitidis is responsible for meningococcal meningitis and septicemia. Therefore, all three choices are correct in producing endotoxins that can cause fever and shock.

Correct Answer: D

Rationale: The correct answer is D: Single stranded segmented (-) RNA. Orthomyxoviridae family includes influenza viruses, which have a genome composed of single-stranded segmented negative-sense RNA. This specific structure allows for efficient replication and transcription within host cells. Choice A is incorrect as orthomyxoviruses do not have a double-stranded DNA genome. Choice B is incorrect because orthomyxoviruses have a negative-sense RNA genome, not a positive-sense RNA genome. Choice C is incorrect as orthomyxoviruses do not have a double-stranded RNA genome.

Correct Answer: A

Rationale: The correct answer is A: Streptococcus pneumoniae. The given characteristics match this bacterium: Gram-positive diplococci, catalase-negative, and alpha-hemolytic. S. pneumoniae is a common cause of community-acquired pneumonia. Other choices are incorrect because Staphylococcus aureus is catalase-positive, Enterococcus faecalis is not alpha-hemolytic, and Klebsiella pneumoniae is not Gram-positive diplococci.