Nokea
What is the primary effector cell in delayed-type hypersensitivity?
- A. Mast cells
- B. T cells
- C. Neutrophils
- D. B cells
Correct Answer: B
Rationale: The primary effector cell in delayed-type hypersensitivity is T cells. T cells play a crucial role in initiating and orchestrating the immune response in delayed hypersensitivity reactions. Upon exposure to the antigen, T cells are activated and release cytokines that recruit and activate macrophages, leading to the inflammatory response characteristic of delayed-type hypersensitivity. Mast cells are involved in immediate hypersensitivity reactions mediated by IgE. Neutrophils are primarily involved in acute inflammation and combating bacterial infections. B cells are responsible for antibody production in humoral immunity, not in delayed hypersensitivity reactions. Therefore, the correct answer is B: T cells.
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In a client with AIDS,a CD4 cell count above ______ mm³ would indicate that antiretroviral therapy is being effective.
- A. 250
- B. 1000
- C. 500
- D. 275
Correct Answer: C
Rationale: A CD4 count above 500 mm³ indicates a strong immune response and effective antiretroviral therapy.
What does the presence of carcinoembryonic antigens (CEAs) and α-fetoprotein (AFP) on cell membranes indicate has happened to the cells?
- A. They have shifted to more immature metabolic pathways and functions
- B. They have spread from areas of original development to different body tissues
- C. They produce abnormal toxins or chemicals that indicate abnormal cellular function
- D. They have become more differentiated as a result of repression of embryonic functions
Correct Answer: A
Rationale: The presence of CEAs and AFP indicates that cells have reverted to more immature metabolic pathways, characteristic of cancerous transformation.
Which enzyme catalyzes the following reaction? Gap 5' - G G-A-T-C-C—3' ⋮ ⋮ ⋮ ⋮ ⋮ 3' - C-C-T-A-G G—5' Gap 5' - G-G-A-T-C-C—3' ⋮ ⋮ ⋮ ⋮ ⋮ 3' - C-C-T-A-G-G—5'
- A. DNA ligase
- B. DNA endonuclease
- C. None of the options are correct
- D. DNA polymerase 1
Correct Answer: A
Rationale: The correct answer is A: DNA ligase. DNA ligase catalyzes the joining of two DNA strands by forming a phosphodiester bond between the 3' hydroxyl of one nucleotide and the 5' phosphate of another. In the given reaction, the enzyme is needed to seal the nick in the DNA strands after the Okazaki fragments have been synthesized during DNA replication.
Explanation of other choices:
B: DNA endonuclease - Endonucleases cleave the phosphodiester bond within a polynucleotide chain, not join two DNA strands.
C: None of the options are correct - This is incorrect as DNA ligase is the correct enzyme for this reaction.
D: DNA polymerase 1 - DNA polymerase synthesizes new DNA strands by adding nucleotides to the 3' end of the growing chain, not joining two DNA strands.
The nurse is caring for a patient who is experiencing an immune response involving B and T cells. Which type of immunity is the patient demonstrating?
- A. Passive immunity
- B. Humoral immunity
- C. Acquired immunity
- D. Cell-mediated immunity
Correct Answer: B
Rationale: The correct answer is B: Humoral immunity. Humoral immunity involves B cells producing antibodies to target pathogens. B cells are responsible for producing antibodies that circulate in the blood and lymph to neutralize pathogens. This type of immunity is specific to antigens and is a key component of the adaptive immune response. Passive immunity (A) is when antibodies are transferred from one individual to another, not involving B and T cells directly. Acquired immunity (C) is a broad term encompassing both humoral and cell-mediated immunity. Cell-mediated immunity (D) involves T cells directly targeting infected cells, not B cells producing antibodies.
What is hypersensitivity in immunology?
- A. An excessive or inappropriate immune response causing tissue damage
- B. The body's inability to mount an immune response
- C. A low-level immune reaction to antigens
- D. A mechanism for faster immune response during infections
Correct Answer: A
Rationale: Step-by-step rationale:
1. Hypersensitivity in immunology refers to an exaggerated or inappropriate immune response.
2. This excessive response can lead to tissue damage and various immune-mediated conditions.
3. Choice A accurately describes this concept.
Summary:
- Choice A is correct as it accurately defines hypersensitivity.
- Choice B is incorrect as hypersensitivity involves an exaggerated immune response, not an inability to mount one.
- Choice C is incorrect as hypersensitivity is not a low-level immune reaction.
- Choice D is incorrect as hypersensitivity is not a mechanism for faster immune response, but rather an overreaction.