Nokea
The daughter of a man with Huntington’s disease is having presymptomatic genetic testing done. What does a positive result mean for her?
- A. She will get the disease.
- B. She is a carrier of Huntington’s disease.
- C. She will be at increased risk for developing the disease.
- D. She should change her diet, exercise, and environment to prevent the disease.
Correct Answer: A
Rationale: Huntington’s disease is dominantly inherited, meaning a positive test indicates she will develop the disease later in life.
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Which of the following statements about innate immunity is TRUE?
- A. It has no role in stimulating adaptive immunity
- B. It requires prior exposure to pathogens to function
- C. It includes both physical and cellular defenses
- D. It is antigen-specific
Correct Answer: C
Rationale: Step 1: Innate immunity is the body's first line of defense against pathogens.
Step 2: Physical defenses include barriers like skin and mucous membranes.
Step 3: Cellular defenses include immune cells like macrophages and natural killer cells.
Step 4: These defenses are present from birth and do not require prior exposure to pathogens.
Step 5: Choice C is true as innate immunity encompasses both physical and cellular defenses, making it the correct answer.
Other choices are incorrect:
A: Innate immunity does play a role in stimulating adaptive immunity through antigen presentation.
B: It does not require prior exposure to function, as it is a rapid and non-specific response.
D: Innate immunity is not antigen-specific; adaptive immunity is responsible for antigen-specific responses.
Which of the following concerning nosocomial infections is incorrect?
- A. Caused by both Gram-negative and Gram-positive
- B. A common example is represented by Helicobacter pylori
- C. Caused by species that are often antibiotic-resistant
- D. Include infections by Clostridium difficile, a bacterial species that is often part of the commensal flora
Correct Answer: B
Rationale: The correct answer is B because Helicobacter pylori is not typically associated with nosocomial infections. Nosocomial infections are usually caused by bacteria commonly found in healthcare settings, such as Clostridium difficile, which is mentioned in choice D. Choices A, C, and D are correct as nosocomial infections can be caused by both Gram-negative and Gram-positive bacteria, often antibiotic-resistant species, and commensal flora bacteria like Clostridium difficile.
Select the wrong statement concerning TLR4
- A. TLR4 is expressed on dendritic cells and macrophages
- B. It represents an example of a phagocytic receptor
- C. It is expressed on the membrane in complex with a protein called MD2
- D. Mice resistant to endotoxic shock harbor a mutation of TLR4
Correct Answer: B
Rationale: The correct answer is B because TLR4 is not a phagocytic receptor, but rather a pattern recognition receptor involved in recognizing pathogen-associated molecular patterns (PAMPs).
A: Correct, TLR4 is expressed on dendritic cells and macrophages.
C: Correct, TLR4 is expressed on the membrane in complex with MD2.
D: Correct, mice resistant to endotoxic shock have a mutation in TLR4, indicating its role in the immune response to endotoxins.
Phagocytosis is not a characteristic of which groups?
- A. protozoans
- B. algae
- C. fungi
- D. Archaea
Correct Answer: D
Rationale: Phagocytosis is a process where cells engulf and digest particles. Archaea lack membrane-bound organelles, including phagosomes, making phagocytosis impossible. Protozoans, algae, and fungi have the necessary cellular structures for phagocytosis. Therefore, the correct answer is D. Protozoans, algae, and fungi can perform phagocytosis due to their cellular structure and function, making choices A, B, and C incorrect.
Which of the following is not usually observed in severe Covid-19 cases?
- A. Prompt and sustained production of type I Interferon
- B. Autoantibodies
- C. A delayed CD4 T cell response
- D. Elevated levels of inflammatory cytokines
Correct Answer: A
Rationale: Step-by-step rationale:
1. In severe Covid-19 cases, there is usually a dysregulated immune response.
2. Type I Interferon plays a crucial role in early antiviral defense.
3. However, in severe cases, there is often a blunted or delayed response of type I Interferon.
4. This delayed response contributes to viral persistence and hyperinflammation.
5. Therefore, the prompt and sustained production of type I Interferon is not usually observed in severe Covid-19 cases.
Summary:
- Choice A is correct as the prompt and sustained production of type I Interferon is not typically observed in severe Covid-19 cases.
- Choices B, C, and D are incorrect as autoantibodies, a delayed CD4 T cell response, and elevated levels of inflammatory cytokines are commonly observed in severe Covid-19 cases.