Nokea
Which of the following is a characteristic of CTL?
- A. They kill target cells through recognition of peptide-MHC class I complexes
- B. They die in the process of killing a target cell
- C. They can kill target cells by activating complement
- D. They carry out their effector function in secondary lymphoid tissues
Correct Answer: A
Rationale: The correct answer is A because cytotoxic T lymphocytes (CTLs) kill target cells by recognizing specific peptide antigens presented on major histocompatibility complex (MHC) class I molecules. This recognition triggers the CTLs to release cytotoxic molecules that induce apoptosis in the target cells. Choice B is incorrect because CTLs do not die in the process of killing target cells; they survive to continue their immune response. Choice C is incorrect as CTLs do not kill target cells by activating complement, but rather through direct cell-cell contact. Choice D is incorrect because CTLs carry out their effector function in peripheral tissues where they encounter target cells, not specifically in secondary lymphoid tissues.
You may also like to solve these questions
You are working with a student nurse who is assigned to care for an HIV-positive patient with severe esophagitis caused by Candida albicans. Which action by the student indicates that you need to intervene most quickly?
- A. The student puts on a mask and gown before entering the patient room.
- B. The student gives the patient a glass of water after the oral nystatin (Mycostatin) suspension.
- C. The student offers the patient a choice of chicken soup or chile con carne for lunch.
- D. The student places a “No Visitors” sign on the door of the patient’s room.
Correct Answer: B
Rationale: The student should not give the patient water immediately after administering oral nystatin as it can wash away the medication before it has a chance to coat the esophagus and treat the infection. The other actions are appropriate: wearing protective gear offering food choices and limiting visitors to reduce infection risk.
To produce better flu vaccines, we want:
- A. To block spreading of the infection by inducing a cytotoxic T cell response that would directly prevent viral entry into uninfected cells
- B. To induce the formation of strain-specific neutralizing antibodies that would prevent viral entry into uninfected cells
- C. To induce antibodies able to recognize HA across different strains by targeting less variable regions of HA
- D. All of the above is reasonably expected to improve the success of flu vaccines
Correct Answer: D
Rationale: The correct answer is D because all the options contribute to improving flu vaccines. A cytotoxic T cell response can help block viral spread, strain-specific neutralizing antibodies can prevent viral entry, and targeting less variable regions of HA with antibodies can improve recognition across strains. Each approach addresses different aspects of the immune response to enhance vaccine efficacy. Therefore, combining these strategies can lead to a more comprehensive and effective flu vaccine. Options A, B, and C alone are not sufficient as they only target specific aspects of the immune response, while option D encompasses a holistic approach for better vaccine success.
Which group(s) of fungi do not generally produce sexual reproductive structures and are also sometimes known as imperfect fungi?
- A. Ascomycotina
- B. Oomycetes
- C. Zygomycotina
- D. Hyphochridiomycetes
Correct Answer: E
Rationale: I'm sorry, but the correct answer is not provided in the choices given (A, B, C, D). Can you please provide the correct answer so that I can help you with the detailed explanation and summary of why the correct answer is correct and the others are incorrect?
What is the primary function of cytokines in the immune system?
- A. To act as a physical barrier to pathogens
- B. To orchestrate and drive immune responses
- C. To destroy red blood cells
- D. To generate antibodies
Correct Answer: B
Rationale: The correct answer is B: To orchestrate and drive immune responses. Cytokines are signaling molecules that coordinate various aspects of the immune response, such as inflammation, cell proliferation, and differentiation. They regulate communication between immune cells to mount an effective defense against pathogens.
A: To act as a physical barrier to pathogens - Incorrect. Physical barriers include skin and mucous membranes, not cytokines.
C: To destroy red blood cells - Incorrect. Cytokines are not involved in destroying red blood cells.
D: To generate antibodies - Incorrect. While cytokines can influence antibody production, their primary role is not in generating antibodies.
Secondary lymphoid tissues are where:
- A. naïve lymphocytes become activated
- B. VDI gene rearrangement occurs
- C. Somatic hypermutation occurs
- D. Two of these options are correct
Correct Answer: D
Rationale: The correct answer is D because secondary lymphoid tissues are where both A and C processes occur. Naïve lymphocytes become activated in secondary lymphoid tissues through interactions with antigens, leading to their differentiation into effector cells. Somatic hypermutation also occurs in secondary lymphoid tissues, specifically in germinal centers of lymph nodes, leading to the generation of high-affinity antibodies. Option B, VDI gene rearrangement, does not occur in secondary lymphoid tissues; it is a process that happens in the primary lymphoid organs (bone marrow and thymus) during the development of lymphocytes. Thus, options A and C are correct, making the correct answer D.