Microbiology Test Bank

Correct Answer: A

Rationale: The correct answer is A: Toxin production test. Rationale: 1. Diphtheria is caused by a toxin produced by Corynebacterium diphtheriae. 2. To confirm if the carrier is dangerous, we need to test if they are producing the toxin. 3. The toxin production test directly assesses if the bacteria are producing the harmful toxin. 4. Positive results indicate the carrier is dangerous and can transmit the disease to others. Summary of other choices: B: Mouse neutralization test - Used to detect diphtheria antitoxin levels in blood, not to confirm if the carrier is dangerous. C: Immunofluorescence test - Used to detect specific antigens or antibodies, not directly related to confirming the carrier's danger. D: Complement fixation test - Measures immune response, not specific to toxin production confirmation.

Correct Answer: A

Rationale: The correct answer is A: Protozoa. Protozoa are single-celled eukaryotic organisms, meaning they have a nucleus and other membrane-bound organelles. Eukaryotes have complex cellular structures that include a nucleus, mitochondria, and other organelles. Therefore, protozoa are eukaryotes. Viruses (B) are not considered cells and lack cellular structures. Viroids (C) are smaller infectious agents that consist of only RNA, lacking the cellular structure of eukaryotes. Prions (D) are infectious proteins and do not possess cellular structures like eukaryotes. So, protozoa are the only choice that relates to eukaryotes due to their cellular structure.

Correct Answer: A

Rationale: The correct answer is A: Peroxidase and catalase. Peroxidase and catalase are enzymes that break down hydrogen peroxide into water and oxygen. Peroxidase helps in breaking down low levels of hydrogen peroxide, while catalase is crucial for breaking down high levels of hydrogen peroxide efficiently. This process is important for organisms to prevent damage from reactive oxygen species. Choices B, C, and D are incorrect: B: Oxygenase and hydroxylase are enzymes involved in different biochemical reactions and do not break down hydrogen peroxide. C: Cytochrome oxidase and cytochrome B5 are involved in electron transport chain reactions and not in breaking down hydrogen peroxide. D: Oxygenase and catalase are not correct as oxygenase is not involved in hydrogen peroxide breakdown, only catalase is.

Correct Answer: A

Rationale: The correct answer is A: Bacteria. Urinary tract infections (UTIs) are primarily caused by the invasion of bacteria into the urinary tract. Bacteria, especially Escherichia coli (E. coli), are the most common culprits. They enter the urinary tract through the urethra and can multiply in the bladder, leading to infection. Viruses (choice B) and fungi (choice C) are not typical causes of UTIs. "None of the above" (choice D) is incorrect as bacteria are indeed the main cause of UTIs.

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.