Nokea
What is a significant consequence of the evolutionary arms race between hosts and pathogens?
- A. Pathogens evolve slower than hosts
- B. Hosts develop epigenetic changes for immune adaptation
- C. Mutations in hosts always outpace pathogen evolution
- D. Hosts and pathogens remain static in their interactions
Correct Answer: B
Rationale: The correct answer is B because hosts developing epigenetic changes for immune adaptation is a significant consequence of the evolutionary arms race between hosts and pathogens. This adaptation allows hosts to better defend against evolving pathogens over time. This process is dynamic, as both hosts and pathogens continuously evolve in response to each other.
Choice A is incorrect because pathogens can evolve rapidly to adapt to host defenses. Choice C is incorrect because while hosts may have mutations that provide advantages, pathogens can also evolve to overcome host defenses. Choice D is incorrect as the interaction between hosts and pathogens is characterized by constant adaptation and change, not remaining static.
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What is the process called when a specific lymphocyte binds its antigen and proliferates?
- A. Clonal deletion
- B. Clonal selection
- C. Antigen presentation
- D. Cytokine signaling
Correct Answer: B
Rationale: The correct answer is B: Clonal selection. During clonal selection, a specific lymphocyte recognizes its specific antigen, binds to it, and undergoes proliferation to generate a large population of identical cells to combat the antigen efficiently. This process ensures an effective immune response.
Incorrect choices:
A: Clonal deletion - This process involves the elimination of self-reactive lymphocytes to prevent autoimmunity, not the proliferation of antigen-specific lymphocytes.
C: Antigen presentation - This is the process by which antigens are displayed to immune cells for recognition, not the proliferation of lymphocytes.
D: Cytokine signaling - While cytokines play a role in immune responses, they are not directly involved in the proliferation of lymphocytes in response to specific antigens.
Which of the following is NOT a common condition associated with Type I hypersensitivity?
- A. Asthma
- B. Food allergies
- C. Anaphylaxis
- D. Systemic lupus erythematosus (SLE)
Correct Answer: D
Rationale: The correct answer is D: Systemic lupus erythematosus (SLE). Type I hypersensitivity involves IgE-mediated reactions to allergens, leading to immediate responses like asthma, food allergies, and anaphylaxis. SLE is an autoimmune disease involving immune complexes and not IgE antibodies. Therefore, SLE is not directly associated with Type I hypersensitivity. Asthma, food allergies, and anaphylaxis are all examples of Type I hypersensitivity reactions due to IgE-mediated mechanisms.
Which of the following is NOT a function of the immune system?
- A. Promoting wound healing
- B. Fighting cancer
- C. Increasing pathogen reproduction
- D. Eliminating cell debris
Correct Answer: C
Rationale: The correct answer is C: Increasing pathogen reproduction. The immune system's main function is to protect the body from pathogens and foreign invaders, not to promote their reproduction. A: Promoting wound healing is correct as the immune system helps in tissue repair. B: Fighting cancer is correct as the immune system plays a role in recognizing and destroying cancerous cells. D: Eliminating cell debris is correct as the immune system helps in clearing out dead or damaged cells to maintain tissue health.
Tropism is a phenomenon by which
- A. plants response to stimulation
- B. reducing lateral branching
- C. Affected by the length of the day and night
- D. All above
Correct Answer: A
Rationale: The correct answer is A: plants response to stimulation. Tropism refers to the growth or movement of an organism in response to a stimulus. Plants exhibit tropisms such as phototropism (response to light) and geotropism (response to gravity). This choice accurately defines the phenomenon.
Choice B is incorrect because reducing lateral branching is not a defining characteristic of tropism.
Choice C is incorrect because the length of day and night does not directly relate to tropism.
Choice D is incorrect because not all options listed are characteristics of tropism.
Follicular dendritic cells
- A. Are found in the blood
- B. Are important for sustaining antibody responses
- C. Represent a HAART-resistant reservoir of virus in HIV-infected individuals
- D. Can activate naïve T lymphocytes
Correct Answer: E
Rationale: I'm sorry, but the question you provided does not have option E listed. Could you please provide the correct options for the question so I can assist you with a detailed explanation of the correct answer and why the other choices are incorrect?