microbiology an introduction 13th edition test bank

Correct Answer: D

Rationale: The correct answer is D, All of these. Orthopoxvirus genus includes Vaccinia, Smallpox, and Cowpox viruses. They share similar characteristics such as brick-shaped virions and double-stranded DNA genomes. Vaccinia virus is used in smallpox vaccine, Smallpox virus caused the eradicated disease, and Cowpox virus can infect both animals and humans. Therefore, all three viruses belong to the Orthopoxvirus genus. Choices A, B, and C are incorrect because they each represent a different virus from the genus Orthopoxvirus.

Correct Answer: D

Rationale: The correct answer is D: Mesosomes. Mesosomes are infoldings of the prokaryotic cytoplasmic membrane that play a role in cell division and respiration. This structure is not found in eukaryotic cells. Cristae (A) are infoldings of the mitochondrial inner membrane in eukaryotic cells. Granum (B) refers to stacks of thylakoid membranes in chloroplasts. Flagella (C) are whip-like structures used for movement and are not related to cytoplasmic membrane invaginations. Therefore, the correct answer is D as mesosomes are unique to prokaryotic cells and are involved in various cellular processes.

Correct Answer: B

Rationale: The correct answer is B: Quorum sensing in bacteria refers to a process of cell-cell communication. Bacteria release signaling molecules to communicate with each other, coordinating group behaviors such as biofilm formation or virulence factor production when a certain population density is reached. This communication helps bacteria respond collectively to environmental cues. A: Incorrect - Locomotion refers to movement, not communication between bacteria. C: Incorrect - Uptake of foreign DNA is related to genetic transfer mechanisms, not communication. D: Incorrect - Antibiotic resistance mechanisms may involve genetic changes but are not directly related to inter-bacterial communication. In summary, quorum sensing is a vital communication system that allows bacteria to coordinate behaviors for survival and adaptation.

Correct Answer: B

Rationale: The correct answer is B: psittacosis. Psittacosis is an infection caused by Chlamydia psittaci that primarily affects the lower respiratory tract, leading to pneumonia-like symptoms. Mycoplasma pneumoniae causes atypical pneumonia, not pharyngitis (Choice A). Chronic atrophic rhinitis (Choice C) and rhinoscleroma (Choice D) both affect the upper respiratory tract, not the lower respiratory tract. Psittacosis specifically targets the lower respiratory tract, making it the most appropriate answer.

Correct Answer: A

Rationale: The correct answer is A: Lipopolysaccharides. Endotoxins are a type of bacterial toxin found in the outer membrane of Gram-negative bacteria. They consist of lipid A, which is a lipid component, and polysaccharides, making them lipopolysaccharides. Lipoproteins (choice B) and glycoproteins (choice C) do not accurately describe the chemical structure of endotoxins. "None of the above" (choice D) is incorrect as lipopolysaccharides are indeed the chemical structure of endotoxins.