openstax microbiology test bank

Correct Answer: A

Rationale: Step-by-step rationale: 1. Tularemia is caused by Francisella tularensis, a highly infectious bacterium. 2. Francisella tularensis is the only pathogen specifically known to cause tularemia. 3. The other choices (Bordetella pertussis, Brucella suis, Legionella sp.) are not associated with tularemia. 4. Therefore, the correct answer is A - Francisella tularensis.

Correct Answer: B

Rationale: The correct answer is B: lyophilization. This technique involves freezing the sample and then removing the ice through sublimation, preserving the cells in a dry state. Desiccation (A) simply involves drying without freezing. Pasteurization (C) is a heat treatment to kill pathogens, not used for preservation. Radiation (D) can sterilize but doesn't involve freezing and drying like lyophilization.

Correct Answer: A

Rationale: The correct answer is A: Bacillus anthracis. This bacterium is known to form highly resistant spores that can survive for long periods in soil. Bacillus anthracis causes anthrax, a dangerous disease that can be transmitted to humans and animals. The other choices, Francisella tularensis, Brucella abortus, and Yersinia pestis, do not form spores as resistant as Bacillus anthracis. Therefore, only Bacillus anthracis is likely to have survived in the soil of the old burial ground for animal refuse for over 50 years.

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas. Pseudomonas bacteria are known to produce yellow-green pigment and a characteristic odor, specifically in meat-peptone agar. This is due to the production of pyoverdin pigment by Pseudomonas. Other choices like Escherichia, Proteus, Klebsiella, and Azotobacter do not typically produce yellow-green pigment or have a characteristic odor in meat-peptone agar. Therefore, based on the specific characteristics mentioned in the question, Pseudomonas is the most appropriate choice.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Gram-positive cocci in clusters suggest Staphylococcus or Streptococcus. 2. Catalase-positive and coagulase-positive narrow it down to Staphylococcus. 3. Staphylococcus aureus is catalase-positive and coagulase-positive. Therefore, the likely causative agent is Staphylococcus aureus. Summary: A: Correct - Staphylococcus aureus fits all the characteristics. B: Incorrect - Staphylococcus epidermidis is catalase-negative and coagulase-negative. C: Incorrect - Streptococcus pyogenes is catalase-negative and coagulase-negative. D: Incorrect - Enterococcus faecalis is catalase-negative and coagulase-negative.