Nokea
Signal 2 for T cell activation is
- A. Necessary for re-activation of memory T cells
- B. Required to develop tolerance to self-antigens
- C. Mediated by CD3
- D. Essential for the activation of naïve T cells
Correct Answer: D
Rationale: The correct answer is D because Signal 2 is essential for the activation of naïve T cells. Signal 1 provides the antigen recognition, while Signal 2, typically provided by co-stimulatory molecules, is required for full T cell activation. A is incorrect because Signal 2 is not specifically for memory T cell re-activation. B is incorrect because Signal 2 is not related to self-tolerance, which is typically maintained by regulatory T cells. C is incorrect because CD3 is a component of the T cell receptor complex, not the primary mediator of Signal 2.
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Select the correct statement during an allergic reaction.
- A. An allergen binds with IgE antibodies.
- B. The mast cells are deactivated.
- C. The body is immunodeficient.
- D. Helper T cells release histamine.
Correct Answer: A
Rationale: Step-by-step rationale:
1. During an allergic reaction, allergens trigger the release of IgE antibodies.
2. The allergen binds with IgE antibodies, leading to the activation of mast cells.
3. Activated mast cells release histamine and other inflammatory mediators.
4. This cascade of events causes allergic symptoms.
Therefore, option A is correct as it accurately describes the initial binding of allergen with IgE antibodies. Option B is incorrect as mast cells are activated, not deactivated. Option C is incorrect as the body is hypersensitive, not immunodeficient. Option D is incorrect as it is mast cells, not Helper T cells, that release histamine.
Which of the following represents a typical match between pathogen type and Th subset response?
- A. Virus : TH1
- B. Intracellular bacteria : TH2
- C. Virus : TH17
- D. Parasitic worm : TH1
Correct Answer: A
Rationale: The correct answer is A. Virus typically triggers a Th1 response because Th1 cells are specialized in combating intracellular pathogens like viruses. Th2 response is more common for extracellular parasites, making choice B incorrect. TH17 response is usually associated with fungal infections and autoimmune diseases, making choice C incorrect. Parasitic worms usually induce a Th2 response due to their extracellular nature, making choice D incorrect.
Where do B cells mature?
- A. Bone marrow
- B. Thymus
- C. Spleen
- D. Lymph nodes
Correct Answer: A
Rationale: The correct answer is A: Bone marrow. B cells mature in the bone marrow where they develop from hematopoietic stem cells. This process involves gene rearrangement and selection for self-tolerance. The bone marrow provides a microenvironment necessary for B cell development. Choices B, C, and D are incorrect because the thymus is where T cells mature, the spleen is involved in immune responses but not B cell maturation, and lymph nodes are sites for immune cell activation and proliferation but not B cell maturation.
What was the important contribution to microbiology of Anton Van Leeuwenhoek in the 1600s?
- A. He was the first to observe microorganisms
- B. He disproved the theory of spontaneous generation of microorganisms
- C. He was the first to show that a disease could be caused by a microorganism
- D. He was the first to describe the process of fermentation
Correct Answer: A
Rationale: The correct answer is A: He was the first to observe microorganisms. Van Leeuwenhoek's important contribution to microbiology was his discovery of microorganisms using his own handcrafted microscopes. This observation revolutionized the field by providing the first direct evidence of the existence of microorganisms.
Choice B is incorrect because Leeuwenhoek's observations actually supported the idea of spontaneous generation. Choice C is incorrect because he did not link microorganisms to diseases. Choice D is incorrect because the process of fermentation was described by others before Leeuwenhoek.
What is the significance of HER2 positivity in breast cancer?
- A. Indicates aggressive tumor behavior and potential resistance to certain treatments
- B. Signifies slower tumor growth
- C. Indicates sensitivity to hormone therapy
- D. Denotes a benign tumor
Correct Answer: A
Rationale: HER2 positivity signifies aggressive tumor behavior and potential resistance to certain treatments, requiring targeted therapies.