Correct Answer: A

Rationale: The correct answer is A: Treponema. The characteristics described match Treponema pallidum, the causative agent of syphilis. Treponema has long, spiral shape with 8-12 regular coils. Leptospira (B) is a spirochete but has fewer coils and causes leptospirosis. Borrelia (C) is another spirochete but typically has irregular coils and causes Lyme disease. Vibrios (D) are curved rods and not spirochetes.

Correct Answer: D

Rationale: The correct answer is D because fires from flammable metals require specialized Class D fire extinguishers designed to extinguish these unique types of fires. Class A, B, and C fire extinguishers are not suitable for flammable metal fires as they are designed for different types of materials and fire classes. Class A extinguishers are for ordinary combustibles, Class B for flammable liquids, and Class C for electrical fires. Therefore, Class D fire extinguishers are specifically designed for flammable metal fires, making them the correct choice for this scenario.

Correct Answer: D

Rationale: The correct answer is D. Clostridium botulinum produces botulinum toxin, Salmonella enterica produces salmonella toxin, and certain strains of Escherichia coli produce toxins like shiga toxin. These toxins can cause severe foodborne illnesses. Therefore, all of the above bacteria can produce toxins that lead to foodborne illnesses. Choices A, B, and C alone are incorrect because each of these bacteria individually can produce toxins that lead to foodborne illnesses.

Correct Answer: B

Rationale: The correct answer is B: Yersinia pestis. Y. pestis is the causative agent of plague, a serious infectious disease transmitted through fleas. It causes bubonic, pneumonic, and septicemic plague. Bordetella pertussis causes whooping cough, Rickettsia prowazekii causes epidemic typhus, and Treponema pallidum causes syphilis. Y. pestis is the correct answer because it is specifically associated with plague, making the other options incorrect.

Correct Answer: B

Rationale: The correct answer is B: Catalase. Catalase is the enzyme responsible for breaking down hydrogen peroxide into water and oxygen. This process helps protect the bacteria from oxidative damage caused by hydrogen peroxide. Amylase (A), Lipase (C), and Protease (D) are enzymes that are not involved in breaking down hydrogen peroxide. Amylase is involved in breaking down starch, Lipase breaks down lipids, and Protease breaks down proteins. Therefore, they are not the correct enzymes for the given question.