mastering microbiology test bank

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. Pseudomonas aeruginosa is known for producing a blue-green pigment called pyocyanin, which gives the characteristic color seen in the wound abscess. The distinctive odor of jasmine is also a key feature of Pseudomonas aeruginosa. Proteus vulgaris (B) and Klebsiella pneumoniae (D) do not produce blue-green pigment or have a jasmine-like odor. Escherichia coli (C) typically does not produce blue-green pigment or have a jasmine-like odor.

Correct Answer: D

Rationale: Production of auto-antibodies can be due to various factors. Mutant B cell clones can lead to the production of self-reactive antibodies. Antibodies against hidden tissues can also trigger autoimmune responses. Genetic factors play a crucial role in predisposing individuals to autoimmunity. Therefore, the correct answer is D, as all these factors can contribute to the production of auto-antibodies. Choice A is incorrect as it only addresses one possible cause. Choice B is incorrect as it focuses solely on antibodies against hidden tissues. Choice C is incorrect as it overlooks the other potential reasons for auto-antibody production.

Correct Answer: B

Rationale: The correct answer is B: Salmonella enterica. Typhoid fever is caused by the bacterium Salmonella enterica serotype Typhi. This specific strain of Salmonella is responsible for typhoid fever, a serious illness characterized by high fever, abdominal pain, and diarrhea. Escherichia coli (choice A) is not the causative agent of typhoid fever. Shigella flexneri (choice C) causes bacillary dysentery, not typhoid fever. Staphylococcus aureus (choice D) can cause food poisoning but is not associated with typhoid fever.

Correct Answer: A

Rationale: The correct answer is A: axial filaments. Treponemae are motile due to their unique structure of axial filaments, also known as endoflagella. These axial filaments are located within the periplasmic space of the organism and are responsible for the corkscrew-like motility of Treponemae. The other choices (B: mans peritrichous filaments, C: single monotrichous filament, D: fimbriae) do not play a role in the motility of Treponemae. Peritrichous filaments and single monotrichous filaments are not present in Treponemae, and fimbriae are primarily involved in adhesion rather than motility.

Correct Answer: A

Rationale: The correct answer is A: Selective toxicity. Chemotherapy aims to target cancer cells while minimizing harm to healthy cells, known as selective toxicity. This principle is crucial to effectively treat cancer without causing excessive damage to the patient's body. Accumulation in the macroorganism (B) and causing allergies (C) are not fundamental principles of chemotherapy and can lead to harmful side effects. Therefore, the correct answer is A as it aligns with the core objective of chemotherapy.