microbiology an evolving science test bank

Correct Answer: C

Rationale: Rationale: Schizogony is the process in protozoans where multiple nuclear divisions occur before cell division. This results in the formation of multiple daughter cells. - A: Budding is a form of asexual reproduction where a new organism grows from an outgrowth on the parent. - B: Mitosis is a type of cell division that results in two identical daughter cells. - D: Fragmentation is a form of asexual reproduction where an organism breaks into fragments, each developing into a new organism.

Correct Answer: A

Rationale: The correct answer is A: Streptococcus pyogenes. The presence of Gram-positive cocci in chains suggests a streptococcal infection. Beta-hemolysis indicates the production of a hemolysin that lyses red blood cells, a characteristic of Streptococcus pyogenes. This bacterium is known to cause strep throat and can present with fever and sore throat. Summary: - B: Streptococcus pneumoniae is a common cause of pneumonia but typically appears as lancet-shaped cocci, not in chains. - C: Staphylococcus aureus is a gram-positive cocci in clusters, not chains, and is not typically beta-hemolytic. - D: Enterococcus faecalis is a gram-positive cocci that are part of the normal gut flora and are not typically beta-hemolytic or found in chains.

Correct Answer: B

Rationale: The correct answer is B: scalp. Tinea capitis is a fungal infection that specifically affects the scalp. This infection is caused by dermatophytes, which thrive in warm and moist environments. It typically presents with symptoms such as scaling, itching, and hair loss on the scalp. Choices A, C, and D are incorrect because tinea pedis (athlete's foot) affects the feet, oral thrush is a fungal infection of the mouth, and tinea manuum affects the hands. By process of elimination and understanding the specific characteristics of tinea capitis, we can determine that the scalp is the correct location for this fungal infection.

Correct Answer: A

Rationale: Rationale: Shigella dysenteriae produces Shiga toxin, which inhibits protein synthesis by inactivating the 60S ribosomal subunit. This disrupts the translation process, leading to cell death. Escherichia coli (choice B) does not produce a toxin that inhibits protein synthesis. Clostridium tetani (choice C) produces tetanospasmin, which affects the nervous system. Staphylococcus aureus (choice D) produces toxins that cause food poisoning but do not inhibit protein synthesis.

Correct Answer: A

Rationale: The correct answer is A: Gram-negative stain. Pseudomonas aeruginosa is a gram-negative bacterium, as indicated by the bluish-green pus color. This bacterium has an outer membrane that retains the crystal violet stain, making it appear pink/red after the counterstain with safranin in Gram staining. The other choices are incorrect because Pseudomonas aeruginosa does not typically form spores (B), has a rod-shaped morphology rather than a coccal form (C), and does not exhibit cell pairing (D).