Nokea
Which group(s) of fungi do not generally produce sexual reproductive structures and are also sometimes known as imperfect fungi?
- A. Ascomycotina
- B. Oomycetes
- C. Zygomycotina
- D. Hyphochridiomycetes
Correct Answer: E
Rationale: I'm sorry, but the correct answer is not provided in the choices given (A, B, C, D). Can you please provide the correct answer so that I can help you with the detailed explanation and summary of why the correct answer is correct and the others are incorrect?
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A 28-year-old male Gulf War veteran tells the nurse he gets a headache, sore throat, shortness of breath, and nausea when his girlfriend wears perfume and when he was painting her apartment. He is afraid he has cancer. What does the nurse suspect may be the patient’s problem?
- A. He has posttraumatic stress disorder.
- B. He has multiple chemical sensitivities.
- C. He needs to wear a mask when he paints.
- D. He is looking for an excuse to break up with his girlfriend.
Correct Answer: B
Rationale: Multiple chemical sensitivities could explain the patient's symptoms triggered by exposure to various chemicals.
Concerning multiple sclerosis (MS), which of the following is NOT correct
- A. Some HLA alleles confer susceptibility to MS
- B. A gender bias is observed with females more at risk for MS than males
- C. Exhibits a North-South gradient, with a higher incidence reported for populations living above the equator
- D. Affects mostly individuals over 65 yrs. of age
Correct Answer: D
Rationale: The correct answer is D because multiple sclerosis (MS) typically affects individuals between 20-50 years old, with the most common age of onset being between 20-40 years. MS is not primarily a disease of older individuals over 65 years. Choices A, B, and C are incorrect because various HLA alleles have been associated with MS susceptibility, females are indeed more at risk for MS than males, and there is a known North-South gradient in MS incidence, with higher rates reported for populations living farther from the equator.
What is the role of complement component C3b in immune responses?
- A. Initiates MAC formation
- B. Acts as an opsonin to enhance phagocytosis
- C. Triggers inflammation
- D. Neutralizes cytokines
Correct Answer: B
Rationale: The correct answer is B: C3b acts as an opsonin to enhance phagocytosis. C3b binds to pathogens and enhances their recognition by phagocytic cells, facilitating their engulfment and destruction. This process is crucial for efficient immune responses. A, MAC formation, is initiated by the membrane attack complex, not C3b. C, inflammation, is triggered by various mediators such as histamine and cytokines, not C3b. D, neutralizing cytokines, is not a function of C3b; cytokines are regulatory proteins involved in immune responses.
The percentage of developing thymocytes undergoing negative selection in the thymus is close to
- A. 90%
- B. 50%
- C. 25%
- D. 10%
Correct Answer: A
Rationale: The correct answer is A (90%). Negative selection in the thymus eliminates self-reactive T cells. The process ensures self-tolerance. The majority of developing thymocytes are removed during negative selection, making it close to 90%. Choices B, C, and D are incorrect because negative selection eliminates a high percentage of thymocytes, not a lower percentage as indicated in those options.
Sacl restriction endonuclease reactions produce fragments with
- A. blunt end
- B. None of the options are correct
- C. 5' cohesive ends
- D. 3' cohesive ends
Correct Answer: C
Rationale: The correct answer is C: 5' cohesive ends. Sacl restriction endonuclease cuts DNA at specific recognition sites, leaving single-stranded overhangs called cohesive ends. In this case, Sacl creates 5' overhangs, resulting in fragments with 5' cohesive ends. Blunt ends (option A) have no overhangs, making them incorrect. Options B and D are incorrect as they do not align with the specific characteristic of Sacl restriction endonuclease's cleavage pattern.