Nokea
Which of the following statements is true about T regulatory cells
- A. Can produce TGF-β as a regulatory cytokine
- B. Express AIRE
- C. Can control the response of TH1 cells but not that of TH2 cells
- D. Act by killing other T cell subsets
Correct Answer: A
Rationale: Rationale:
A. T regulatory cells can produce TGF-β, which is a key immunosuppressive cytokine regulating immune responses.
B. T regulatory cells do not express AIRE, a transcription factor mainly involved in central tolerance.
C. T regulatory cells can control both TH1 and TH2 responses, maintaining immune homeostasis.
D. T regulatory cells do not act by killing other T cell subsets, but rather through suppressive cytokines and cell-cell interactions.
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What statement accurately describes gene therapy?
- A. May activate a mutated gene that is functioning improperly.
- B. Is a risky technique under study for genetic diseases with no cure.
- C. Is frequently done by replacing a healthy gene with a mutated gene.
- D. Introduces a new gene into reproductive cells to help fight a genetic disease.
Correct Answer: B
Rationale: Gene therapy remains experimental and involves risks, aiming to treat genetic diseases by altering or replacing defective genes.
What does the mechanism of chemotaxis accomplish?
- A. Causes the transformation of monocytes into macrophages
- B. Involves a pathway of chemical processes resulting in cellular lysis
- C. Attracts the accumulation of neutrophils and monocytes to an area of injury
- D. Slows the blood flow in a damaged area, allowing migration of leukocytes into tissue
Correct Answer: C
Rationale: Chemotaxis is the process by which immune cells such as neutrophils and monocytes are attracted to the site of injury or infection through chemical signals. These signals guide the cells to areas where they are needed most.
Which is not a PAMP?
- A. Viral dsRNA
- B. Peptidoglycan
- C. ROS
- D. Flagellin
Correct Answer: C
Rationale: The correct answer is C: ROS (Reactive Oxygen Species) is not a PAMP (Pathogen-Associated Molecular Pattern) because it is not a specific molecular pattern derived from pathogens. PAMPs are recognized by the innate immune system to trigger an immune response. Viral dsRNA, peptidoglycan, and flagellin are all examples of PAMPs as they are specific molecules commonly found in pathogens that can be recognized by pattern recognition receptors (PRRs) on immune cells, leading to activation of the immune response.ROS, on the other hand, are reactive molecules produced by host cells in response to pathogens but are not specific molecular patterns derived from pathogens. Therefore, ROS is not considered a PAMP.
Hfr strains of bacteria:
- A. do not have an 'F' (fertility) factor.
- B. have an 'F' factor plasmid.
- C. have an 'F' factor integrated in the bacterial chromosome.
- D. transfer the genetic information to other bacteria with ow frequency.
Correct Answer: C
Rationale: The correct answer is C because Hfr strains of bacteria have the F factor integrated into their bacterial chromosome. This integration allows for the transfer of genetic material during conjugation. This integration results in a high frequency of genetic information transfer to recipient cells, which is a characteristic of Hfr strains.
Choice A is incorrect because Hfr strains do have the F factor, but it is integrated into their chromosome, not absent. Choice B is incorrect because Hfr strains do not just have an F factor plasmid; it is integrated into the chromosome. Choice D is incorrect because Hfr strains actually transfer genetic information with high frequency, not low frequency.
Flu neuraminidase is
- A. A protein that allows the virus to escape the host immune response
- B. A surface protein that allows the release of newly formed viral particles
- C. The target of Tamiflu
- D. Both B and C are correct
Correct Answer: D
Rationale: The correct answer is D because flu neuraminidase is a surface protein that allows the release of newly formed viral particles and it is also the target of Tamiflu. Neuraminidase helps the virus spread by cleaving sialic acid from host cells, facilitating the release of viral particles. Tamiflu inhibits neuraminidase, preventing the spread of the virus. Option A is incorrect because neuraminidase does not directly help the virus escape the host immune response. Option B is partially correct but incomplete without mentioning Tamiflu. Option C is also partially correct but incomplete without mentioning the role of neuraminidase in releasing viral particles.