The central dogma concerning the flow of information from genetic material was first introduced by

Correct Answer: B

Rationale: The central dogma of molecular biology, which describes the flow of genetic information from DNA to RNA to proteins, was first proposed by Francis Crick. Crick, along with James Watson, discovered the structure of DNA in 1953, leading to the understanding of how genetic information is stored and transmitted. Ernst Ruska was a physicist who developed the electron microscope, not related to genetic information flow. Camillo Golgi was an Italian biologist known for the discovery of the Golgi apparatus, not central to the central dogma. Carl Bender is not a prominent figure in the field of molecular biology. In summary, Francis Crick is the correct answer as he played a pivotal role in introducing the central dogma of molecular biology.

Correct Answer: B

Rationale: The correct answer is B: Legionella and Neisseria are both gram-negative aerobic rods and cocci. Legionella is a rod-shaped bacterium, while Neisseria is a diplococcus. Both are aerobic, meaning they require oxygen for growth. The other choices are incorrect because Legionella and Neisseria are not facultative anaerobes (A), spirochetes (C), or anaerobic cocci (D). Understanding the characteristics of these bacteria helps in differentiating and selecting the correct answer.

Correct Answer: A

Rationale: The correct answer is A: spleen. The spleen is not a component of the gastrointestinal tract; it is part of the lymphatic system. The pharynx, esophagus, and stomach are all part of the gastrointestinal tract responsible for digestion and absorption of food. The spleen's main functions include filtering blood, storing blood cells, and supporting the immune system, making it unrelated to the digestive process.

Correct Answer: A

Rationale: Step-by-step rationale for why Answer A (Sabouraud's) is correct: 1. Sabouraud's agar is a selective medium for fungi. 2. Candida is a type of fungus causing candidosis. 3. Sabouraud's agar promotes fungal growth. 4. Candida will grow on Sabouraud's agar, confirming the diagnosis. 5. Other choices are for bacterial culture, not suitable for fungal growth. Summary: - Endo, Jensen's, and Roux are not appropriate for fungal culture. - Sabouraud's agar specifically supports fungal growth, making it the correct choice for confirming candidosis.

Correct Answer: D

Rationale: The correct answer is D because Borrelia burgdorferi cannot be detected with Giemsa stain. Giemsa stain is commonly used to visualize blood smears for malaria parasites but is not effective for Borrelia burgdorferi detection. A: Borrelia burgdorferi can be cultivated on blood agar - This is correct. Borrelia burgdorferi can be grown in culture on a special medium like Barbour-Stoenner-Kelly (BSK) agar. B: Borrelia burgdorferi is flexible, motile spirochete - This is correct. Borrelia burgdorferi is a spiral-shaped bacterium that moves using a corkscrew motion. C: Borrelia burgdorferi is transmitted by arthropods- ticks - This is correct. Borrelia burgdorferi is primarily transmitted to humans through the bite of infected ticks, particularly Ixodes

Correct Answer: C

Rationale: The correct answer is C: Measles serological test. This is because the clinical presentation of high fever, maculopapular rash, and Filatov-Koplik's spots on the buccal mucosa are classic symptoms of measles. The presence of Filatov-Koplik's spots is highly specific for measles. Performing a measles serological test will help confirm the diagnosis by detecting measles-specific antibodies in the blood. Incorrect choices: A: Mumps serological test - Mumps typically presents with parotitis (swelling of the parotid glands) and not with Filatov-Koplik's spots. B: Enteroviruses serological test - Enteroviruses do not typically cause Filatov-Koplik's spots or the classic triad of symptoms seen in measles. D: Influenza virus serological test - Influenza virus does not cause Filatov-Koplik's spots and the characteristic rash seen

Correct Answer: C

Rationale: Step 1: Anthrax causative agent is Bacillus anthracis, which forms spores. Step 2: Spores are highly resistant structures that can survive for a long time. Step 3: These spores can germinate into active bacteria when conditions are favorable. Step 4: The presence of spores in the powder makes it dangerous even long after being mailed. Summary: A: Incorrect - Anthrax does not form a protein capsule. B: Incorrect - Anthrax does not form a polysaccharide capsule. C: Correct - Anthrax forms spores that are highly resistant. D: Incorrect - Anthrax does not form flagella.

Correct Answer: B

Rationale: Gas gangrene is caused by Clostridium perfringens due to its ability to produce gas in tissues leading to necrosis. Other choices are incorrect: A (C. difficile causes diarrhea), C (C. tetani causes tetanus), and D (incorrect as B is the causative agent).

Correct Answer: B

Rationale: The correct answer is B: Cholera. Cholera is caused by Gram-negative curved rod-like bacteria called Vibrio cholerae, commonly found in contaminated water or food. The characteristic symptom of cholera is profuse watery diarrhea, which matches the patient's presentation. Typhoid fever (A) is caused by Salmonella typhi, which is not a curved rod-like bacteria. Diphtheria (C) is caused by Corynebacterium diphtheriae, a Gram-positive bacterium, and does not typically cause diarrhea. Intestinal form of plague (D) is caused by Yersinia pestis, which is not a curved rod-like bacteria and does not typically present with diarrhea.