The decrease in blood clotting by heparin occurs at which general site of action?

Correct Answer: B

Rationale: The correct answer is B: Extracellular. Heparin works by inhibiting clotting factors in the blood outside of cells, preventing the formation of blood clots. It does not directly affect cellular, neuromuscular, or intracellular processes. By targeting extracellular factors, heparin effectively reduces the ability of blood to clot, making it an effective anticoagulant. The other choices are incorrect because heparin does not act on cellular, neuromuscular, or intracellular sites in the body to decrease blood clotting.

Correct Answer: A

Rationale: The correct answer is A: TRUE. Poxviruses are indeed the largest viruses known, ranging from 200-450 nm in size, which is close to the resolution limit of a light microscope. This makes them almost visible under a light microscope. Explanation: 1. Poxviruses have complex structures and are among the largest viruses. 2. Light microscopes have a resolution limit of around 200 nm. 3. Poxviruses fall within the size range that is close to the resolution limit of a light microscope. 4. Therefore, poxviruses are almost visible under a light microscope. Summary: Choice B is incorrect because poxviruses are indeed large enough to be almost visible under a light microscope. Choice C is incorrect as it implies uncertainty, but poxviruses are consistently close to the resolution limit of a light microscope. Choice D is incorrect as the size of poxviruses being almost visible under a light microscope is a factual statement, not dependent

Correct Answer: A

Rationale: The correct answer is A: Escherichia coli. E. coli is the most common bacteria responsible for causing urinary tract infections due to its ability to adhere to the urinary tract lining and multiply rapidly. It is a normal inhabitant of the gut and can enter the urinary tract through improper hygiene practices. Salmonella enterica and Neisseria gonorrhoeae are typically associated with other infections like food poisoning and gonorrhea, respectively. Mycobacterium tuberculosis causes tuberculosis, not urinary tract infections. Thus, based on its prevalence and pathogenicity in the urinary tract, E. coli is the correct choice.

Correct Answer: B

Rationale: The correct answer is B: As a result of mosquito's bites. Sleeping sickness, also known as African trypanosomiasis, is caused by the parasite Trypanosoma transmitted by tsetse flies, not mosquitoes. Tsetse flies are primarily found in Africa, not South America. Choice A is incorrect as bug bites do not transmit sleeping sickness. Choice C is incorrect as contaminated fruits and vegetables do not transmit the disease. Choice D is incorrect as dirty hands do not play a role in the transmission of sleeping sickness.

Correct Answer: A

Rationale: The correct answer is A: The pyocyanin released by Pseudomonas aeruginosa. Pyocyanin is a blue-green pigment produced by Pseudomonas aeruginosa, a common cause of nosocomial infections in burn patients. The presence of blue-green pus and gram-negative rods in the wound along with fever suggests an infection with Pseudomonas aeruginosa. The other choices are incorrect because E. Coli typically causes gastrointestinal infections and releases enterotoxins, Staphylococcus aureus releases hemolysins causing hemolysis of red blood cells, and Shigella dysenteriae releases shigatoxin causing bloody diarrhea, none of which match the clinical presentation described in the question.

Correct Answer: D

Rationale: The correct answer is D, All of these. Orthopoxvirus genus includes Vaccinia, Smallpox, and Cowpox viruses. They share similar characteristics such as brick-shaped virions and double-stranded DNA genomes. Vaccinia virus is used in smallpox vaccine, Smallpox virus caused the eradicated disease, and Cowpox virus can infect both animals and humans. Therefore, all three viruses belong to the Orthopoxvirus genus. Choices A, B, and C are incorrect because they each represent a different virus from the genus Orthopoxvirus.

Correct Answer: D

Rationale: The correct answer is D: Neuraminidase inhibitors. Neuraminidase is an enzyme crucial for the release of new viral particles from infected cells during influenza infection. By inhibiting neuraminidase, the spread of the virus is limited. Protease inhibitors (choice A) are used to treat HIV, not influenza. Beta-lactamase inhibitors (choice B) are used in combination with beta-lactam antibiotics to increase their effectiveness against bacteria, not viruses. Reverse transcriptase inhibitors (choice C) are used to treat HIV by blocking the enzyme responsible for replicating the virus's genetic material, but they are not effective against influenza.

Correct Answer: A

Rationale: The correct answer is A: Sabouraud. Sabouraud agar is specifically designed to promote the growth of fungi due to its low pH and high glucose content. The cream-like colonies indicate fungal growth, as fungi often appear as fluffy or powdery colonies on Sabouraud agar. Lowenstein-Jensen is used for mycobacteria, Roux for diphtheria, and Loeffler for Corynebacterium diphtheriae. Therefore, Sabouraud is the most suitable medium for detecting fungal contamination based on the characteristics of the colonies formed.

Correct Answer: A

Rationale: Step 1: Vibrio cholerae is a bacterium known to cause cholera, a foodborne illness transmitted through contaminated water. Step 2: Cholera outbreaks are often linked to unsanitary water sources, making Vibrio cholerae the correct choice. Step 3: Clostridium difficile causes gastrointestinal infections, not typically associated with contaminated water. Step 4: Mycobacterium tuberculosis causes tuberculosis, a respiratory disease, not related to foodborne illnesses. Step 5: Neisseria gonorrhoeae is a sexually transmitted bacterium, not linked to foodborne illnesses from contaminated water.