A microscope that provides a three-dimensional image of a specimen is a

Correct Answer: D

Rationale: The correct answer is D: scanning electron microscope. A scanning electron microscope provides a three-dimensional image of a specimen by scanning a focused electron beam across the surface of the specimen, detecting the electrons that are emitted from the surface, and creating a detailed image. This is achieved through the detection of secondary electrons, backscattered electrons, and X-rays emitted from the specimen surface. A dark-field microscope (choice A) utilizes oblique lighting to enhance contrast and is not specifically designed to provide a 3D image. A transmission electron microscope (choice B) uses a beam of electrons transmitted through a specimen to create a 2D image at high magnification. A bright-field microscope (choice C) is a basic microscope that illuminates a specimen with uniform light and does not provide a 3D image like a scanning electron microscope does.

Correct Answer: B

Rationale: The correct answer is B: Zoonosis. Tularemia is primarily a zoonotic disease, meaning it is transmitted from animals to humans. The bacterium that causes tularemia, Francisella tularensis, commonly infects animals like rabbits, rodents, and ticks, which serve as reservoir hosts. Humans can get infected through direct contact with infected animals, insect bites, or contaminated water or soil. This zoonotic nature of tularemia distinguishes it from anthroponosis (A), which is transmitted only between humans, and sapronosis (C), which is transmitted through non-living environmental sources. Choice D is incorrect because there is a correct answer, which is zoonosis.

Correct Answer: A

Rationale: Rationale: Vibrio cholerae produces the exotoxin responsible for severe diarrhea. It causes cholera by disrupting the normal functioning of the intestines. Clostridium botulinum causes botulism, not diarrhea. Streptococcus pyogenes causes strep throat and skin infections. Salmonella enterica causes food poisoning, not severe diarrhea. Therefore, the correct answer is A.

Correct Answer: B

Rationale: The correct answer is B: Hepatitis B virus. This is because Hepatitis B virus is a DNA virus, not an RNA virus. The other choices, A (Hepatitis G virus), C (Hepatitis A virus), and D (Hepatitis E virus) are all RNA viruses. Hepatitis B virus is unique as it contains partially double-stranded DNA. DNA viruses replicate through a DNA intermediate, unlike RNA viruses which directly use RNA. Therefore, Hepatitis B virus stands out as the only DNA virus among the given options.

Correct Answer: A

Rationale: The correct answer is A: OSHA. The Occupational Safety and Health Administration (OSHA) is responsible for setting and enforcing safety standards in the workplace, including bloodborne pathogen training requirements. OSHA's Bloodborne Pathogens Standard mandates training for certain at-risk professions to prevent exposure to bloodborne diseases. The CDC (Choice B) focuses on disease prevention and control, not regulatory enforcement. NIA (Choice C) is the National Institute on Aging and not relevant to bloodborne training. WHO (Choice D) is the World Health Organization, which sets global health standards but does not regulate workplace safety in the same capacity as OSHA.