Nokea
If you were to observe the activity of methylated DNA, you would expect it to
- A. be unwinding in preparation for protein synthesis.
- B. be replicating nearly continuously.
- C. have turned off or slowed down the process of transcription.
- D. induce protein synthesis by not allowing repressors to bind to it.
Correct Answer: C
Rationale: The correct answer is C because methylation of DNA typically results in the inhibition or slowing down of transcription. Methylated DNA attracts proteins that bind to it, preventing transcription factors from accessing the DNA and initiating transcription. This interference with the transcription process leads to gene silencing or reduced gene expression.
A: DNA unwinding in preparation for protein synthesis is unrelated to DNA methylation.
B: Continuous replication is not a typical consequence of DNA methylation.
D: Methylation does not directly induce protein synthesis but rather affects transcription by influencing gene expression.
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A good vaccine will:
- A. Be highly pathogenic
- B. Be highly immunogenic
- C. Induce herd immunity in a vaccinated individual
- D. All of the above
Correct Answer: B
Rationale: The correct answer is B: Be highly immunogenic. A good vaccine should effectively stimulate the immune system to produce a strong immune response against the targeted pathogen while being safe for the individual. This is crucial for developing immunity without causing harm.
Choice A (Be highly pathogenic) is incorrect because a vaccine should not cause disease or harm to the individual receiving it. Choice C (Induce herd immunity in a vaccinated individual) is also incorrect as herd immunity refers to protection of a population, not an individual.
In summary, a good vaccine should be highly immunogenic to effectively trigger an immune response without causing harm, leading to protection against the targeted pathogen.
A major antibody-mediated mechanism of defense against parasitic worms involves:
- A. Neutrophil degranulation
- B. Opsonization
- C. Triggering of physiological responses (such as coughing) that expel the worm
- D. Neutralization by IgE along the mucosal surface of the gut
Correct Answer: D
Rationale: The correct answer is D because neutralization by IgE along the mucosal surface of the gut is a major antibody-mediated mechanism against parasitic worms. IgE binds to antigens on the worm's surface, leading to the release of histamine and other mediators that help expel the worm. Neutrophil degranulation (A) is more associated with bacterial infections, opsonization (B) is mainly for phagocytosis of pathogens, and triggering physiological responses (C) is not a direct antibody-mediated defense against parasitic worms.
A client has been newly diagnosed with systemic lupus erythematosus and is reviewing self-care measures with the nurse. Which statement by the client indicates a need to review the material?
- A. I will avoid direct sunlight as much as possible.
- B. Baby powder is good for the constant sweating.
- C. Grouping errands will help prevent fatigue.
- D. Rest time will have to become a priority.
Correct Answer: B
Rationale: The correct answer is B. Baby powder is not recommended for individuals with systemic lupus erythematosus, as it can irritate the skin and worsen symptoms. A: Avoiding direct sunlight is crucial due to photosensitivity. C: Grouping errands helps conserve energy. D: Rest is important to manage fatigue. Summary: A, C, and D are all appropriate self-care measures for a client with systemic lupus erythematosus, while using baby powder is not recommended.
Memory T cells
- A. Recirculate through blood and secondary lymphoid tissues
- B. Have never encountered antigen
- C. Have a lower threshold of activation than naïve T cells
- D. Have a higher frequency than their naïve counterparts
Correct Answer: C
Rationale: The correct answer is C because memory T cells have a lower threshold of activation than naïve T cells. This is because memory T cells have already been primed by previous exposure to antigens, making them more responsive upon re-exposure. This heightened sensitivity allows memory T cells to mount a faster and stronger immune response upon encountering the same antigen again.
Choice A is incorrect because memory T cells primarily reside in peripheral tissues and not in secondary lymphoid tissues. Choice B is incorrect because memory T cells have encountered antigens before. Choice D is incorrect because memory T cells exist in a lower frequency compared to naïve T cells due to clonal expansion during the primary immune response.
Severe combined immunodeficiency (SCID) is a disease caused by:
- A. Infection with human immunodeficiency virus
- B. One of several inherited genetic mutations
- C. Deficiency of both innate and adaptive immune components
- D. Deficiency of hematopoietic stem cells
Correct Answer: B
Rationale: Step 1: SCID is a genetic disorder affecting the immune system.
Step 2: Inherited genetic mutations cause abnormalities in immune cells.
Step 3: These mutations lead to severe deficiencies in immune function.
Step 4: Choice B accurately reflects the genetic basis of SCID.
Summary: Choice A is incorrect because SCID is not caused by HIV. Choice C is incorrect as it oversimplifies the immune deficiencies in SCID. Choice D is incorrect because SCID primarily affects immune cells, not stem cells.