Nokea
Allergy to penicillin is an example of:
- A. Type I hypersensitivity reaction
- B. Type II hypersensitivity reaction
- C. Type III hypersensitivity reaction
- D. Type IV hypersensitivity reaction
Correct Answer: A
Rationale: Step-by-step rationale for choice A being correct:
1. Penicillin allergy involves IgE antibodies binding to penicillin.
2. This triggers mast cell degranulation, releasing histamine.
3. Histamine causes allergic symptoms like rash, swelling.
4. This immune response characterizes Type I hypersensitivity reactions.
Summary of other choices:
B: Type II reactions involve antibody-mediated cell destruction, not seen in penicillin allergy.
C: Type III reactions involve immune complex deposition, not typical in penicillin allergy.
D: Type IV reactions are delayed hypersensitivity reactions, not immediate like penicillin allergy.
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Which strain E. coli can cause bloody diarrhea in children similar to shigellosis
- A. ETEC
- B. EIEC
- C. EAEC
- D. EPEC
Correct Answer: B
Rationale: The correct answer is B: EIEC. This strain of E. coli can cause bloody diarrhea in children similar to shigellosis due to its ability to invade and replicate within the intestinal epithelial cells, leading to inflammation and bloody stools. ETEC (A) causes watery diarrhea due to enterotoxins. EAEC (C) causes persistent diarrhea. EPEC (D) causes attaching and effacing lesions on the intestinal mucosa without invasion.
Ionizing radiation involves all of the following except
- A. UV light
- B. Gamma rays
- C. Electron beams
- D. X-rays
Correct Answer: A
Rationale: Ionizing radiation has enough energy to remove tightly bound electrons from atoms, creating charged particles (ions). UV light does not have enough energy to ionize atoms, making choice A the correct answer. Gamma rays, electron beams, and X-rays all have sufficient energy to cause ionization. Gamma rays are very high-energy electromagnetic radiation, electron beams are streams of high-energy electrons, and X-rays are high-energy electromagnetic radiation as well.
Examination of a smear from a chancre revealed mobile, long, spiral microorganisms with 8-12 regular coils. What is the causative agent?
- A. Treponema
- B. Leptospira
- C. Borrelia
- D. Vibrios
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.
For family Rhabdoviridae is true that:
- A. They are enveloped viruses
- B. They cause plague
- C. They have spherical shape
- D. They infect only humans
Correct Answer: A
Rationale: The correct answer is A: They are enveloped viruses. Rhabdoviridae family consists of enveloped viruses, which means they have a lipid envelope surrounding their protein coat. This envelope helps the virus in infecting host cells and evading the immune system. The other choices are incorrect because B: They cause plague is not true as Rhabdoviridae family typically causes diseases like rabies in mammals. C: They have spherical shape is incorrect as rhabdoviruses have a bullet-shaped structure. D: They infect only humans is also incorrect as Rhabdoviridae viruses can infect a wide range of hosts beyond just humans.
In humans, the embryonic phase of development extends from fertilization to the end of week __________, after which the developing infant is called a fetus.
- A. 2
- B. 6
- C. 8
- D. 12
Correct Answer: C
Rationale: The correct answer is C: 8. The embryonic phase in humans lasts until the end of week 8. During this time, the major organs and structures of the body begin to form. After week 8, the developing organism is referred to as a fetus. Choice A (2) is too early for this transition to occur, Choice B (6) is also premature, and Choice D (12) is too late as the embryonic phase ends before week 12. Therefore, the correct answer is C (8) as it accurately reflects the timeline of embryonic development in humans.