Nokea
The reason for using Taq polymerase for PCR is that
- A. it has regions that are complementary to primers.
- B. only minute amounts are needed for each cycle of PCR
- C. it binds more readily than other polymerases to primer.
- D. it is heat stable and can withstand the temperature changes of the cycler.
Correct Answer: D
Rationale: The correct answer is D because Taq polymerase is heat-stable, allowing it to withstand the high temperatures used in PCR cycles without denaturing. This heat stability is crucial for the repeated heating and cooling cycles in PCR. Choice A is incorrect because Taq polymerase does not need to be complementary to primers. Choice B is incorrect because the amount needed is not the main reason for using Taq polymerase. Choice C is incorrect because binding affinity to primers is not the primary reason for using Taq polymerase.
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What is the primary goal of palliative care in cancer treatment?
- A. Cure the disease
- B. Extend life expectancy
- C. Relieve suffering and improve quality of life
- D. Prevent disease recurrence
Correct Answer: C
Rationale: Palliative care focuses on relieving suffering and improving quality of life for patients with advanced cancer.
Which condition is caused by a Type IV hypersensitivity reaction?
- A. Anaphylaxis
- B. Sarcoidosis
- C. Grave's disease
- D. Goodpasture's syndrome
Correct Answer: B
Rationale: The correct answer is B: Sarcoidosis. Type IV hypersensitivity reactions are mediated by T cells and are characterized by delayed onset inflammatory responses. Sarcoidosis is a granulomatous disease where T cells form granulomas in affected tissues. Anaphylaxis (A) is a Type I hypersensitivity reaction involving IgE antibodies. Grave's disease (C) is an autoimmune disorder caused by Type II hypersensitivity reaction mediated by antibodies. Goodpasture's syndrome (D) is a Type II hypersensitivity reaction involving antibodies attacking basement membranes. Therefore, the correct answer is B as it fits the characteristics of a Type IV hypersensitivity reaction.
Which pairing of immune response type and immune response feature is not correct?
- A. Innate: Acts rapidly
- B. Adaptive: Results in memory
- C. Innate: Mediated by lymphocytes
- D. Adaptive: Can distinguish between specific pathogens
Correct Answer: C
Rationale: The correct answer is C because innate immune response is not mediated by lymphocytes. Innate response involves physical barriers, such as skin and mucous membranes, and cells like macrophages and neutrophils. Lymphocytes are part of the adaptive immune response, which is characterized by specificity and memory. Choice A is correct as the innate response acts rapidly due to pre-existing mechanisms. Choice B is correct as adaptive response results in memory cells for quicker response upon re-exposure. Choice D is correct as adaptive response can recognize and respond to specific pathogens through antigen recognition.
Treatment with two nucleoside reverse transcriptase inhibitors (NRTIs) and a protease inhibitor (PI) is prescribed for a patient with HIV infection who has a CD4+ T-cell count of <400/µL. The patient asks why so many drugs are necessary for treatment. What should the nurse explain as the primary rationale for combination therapy?
- A. Cross-resistance between specific antiretroviral drugs is reduced when drugs are given in combination.
- B. Combinations of antiretroviral drugs decrease the potential for development of antiretroviral-resistant HIV variants.
- C. Side effects of the drugs are reduced when smaller doses of three different drugs are used rather than large doses of one drug.
- D. When CD4+ T-cell counts are <500/µL, a combination of drugs that have different actions is more effective in slowing HIV growth.
Correct Answer: B
Rationale: Combination therapy minimizes the chance of developing resistant HIV strains by targeting the virus at multiple points in its lifecycle.
Class switching of immunoglobulins occurs
- A. Usually with booster immunizations, going from IgM to IgG
- B. binds complement
- C. causes the histamine release
- D. mediates immunoglobulin class switching
Correct Answer: A
Rationale: The correct answer is A because class switching of immunoglobulins typically occurs during an immune response, leading to the production of antibodies of different classes like IgM to IgG. This process helps enhance the immune response and memory. Choice B, binding complement, refers to the function of antibodies in the classical pathway of the complement system, not class switching. Choice C, causing histamine release, is typically associated with IgE antibodies in allergic reactions, not class switching. Choice D, mediating immunoglobulin class switching, is too vague and does not provide a clear explanation compared to choice A.