Basic Immune System Quizlet

Basic Immune System Quizlet Related

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What is the main function of the Membrane Attack Complex (MAC)?

  • A. Recruitment of neutrophils
  • B. Phagocytosis activation
  • C. Lysis of pathogens
  • D. Enhancing cytokine production
Correct Answer: C

Rationale: The main function of the Membrane Attack Complex (MAC) is to lyse pathogens by creating pores in their cell membranes. First, MAC assembles on the pathogen's surface. Then, it forms a pore, disrupting the pathogen's membrane integrity, leading to cell lysis. This mechanism is crucial for the immune system to effectively eliminate pathogens.

Choice A (Recruitment of neutrophils) is incorrect because MAC is not involved in recruiting neutrophils. Neutrophil recruitment is typically mediated by other signaling molecules.

Choice B (Phagocytosis activation) is incorrect as MAC does not directly activate phagocytosis. Phagocytosis is a separate process involving the engulfment of pathogens by immune cells.

Choice D (Enhancing cytokine production) is incorrect because MAC does not directly enhance cytokine production. Cytokine production is mainly regulated by other immune cells and signaling pathways.

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Epithelial cells at mucosal sites have barrier functions exerted through several mechanisms. These mechanisms do not include:

  • A. Secretion of mucins
  • B. Secretion of antimicrobial peptides
  • C. Phagocytosis of microbes
  • D. Tight junctions
Correct Answer: C

Rationale: The correct answer is C: Phagocytosis of microbes. Epithelial cells primarily act as a physical barrier to prevent the entry of microbes. Phagocytosis is a function of immune cells, not epithelial cells. A: Secretion of mucins helps trap pathogens. B: Secretion of antimicrobial peptides aids in defense. D: Tight junctions form a physical barrier between cells. Therefore, phagocytosis is not a direct mechanism exerted by epithelial cells at mucosal sites.

Which of the following molecular interactions mediate signal 2 during activation of naïve T cells

  • A. L-Selectin/PNAD
  • B. CD4/MHC II or CD8/MHC I
  • C. TCR/MHC I or TCR/MHC II
  • D. TCR/CD3
Correct Answer: E

Rationale: I'm sorry, but there seems to be a mistake in the question as the correct answer is not listed among the choices provided. Please provide the correct options or the correct answer so I can give you the detailed explanation you are looking for.

Which of the following statements concerned with the microbiota is NOT true?

  • A. It colonizes our body at birth
  • B. Its composition in adults is influenced by several factors, including diet and exercise
  • C. Obesity is associated with alterations in the composition of gut microbiota. This condition has been shown to be transmissible in mice when microbiota from obese mice is transferred to lean mice
  • D. Bacteria found in obese mice are less efficient at extracting energy from food and this in turn impacts on the sense of satiety of the animal.
Correct Answer: D

Rationale: The correct answer is D because it is the only statement that is not entirely true regarding the microbiota. The rationale for this is that bacteria found in obese mice are actually more efficient at extracting energy from food, not less efficient as mentioned in option D. This increased efficiency contributes to the higher energy extraction from food, leading to weight gain in obese individuals. The other options (A, B, C) are correct as they align with current research and understanding of the microbiota. Option A is true as the microbiota begins to colonize our body at birth. Option B is also true as the composition of the microbiota in adults can indeed be influenced by various factors such as diet and exercise. Option C is true as obesity has been linked to alterations in gut microbiota composition, and studies have shown that transferring microbiota from obese to lean mice can induce weight gain in the lean mice.

What is the medical term for the breakdown of red blood cells?

  • A. Leukocytosis
  • B. Thrombocytosis
  • C. Hemolysis
  • D. Anemia
Correct Answer: C

Rationale: The correct answer is C: Hemolysis. Hemolysis is the medical term for the breakdown of red blood cells. This process releases hemoglobin and other components into the bloodstream. Leukocytosis (A) is an increase in white blood cells, thrombocytosis (B) is an increase in platelets, and anemia (D) is a decrease in red blood cells or hemoglobin levels. In this context, hemolysis specifically refers to the breakdown of red blood cells, making it the correct answer.

Which of the following are not found in Cyanobacteria?

  • A. thylakoids
  • B. gas vesicles
  • C. chloroplasts
  • D. heterocysts
Correct Answer: C

Rationale: The correct answer is C: chloroplasts. Cyanobacteria do not have chloroplasts because they are prokaryotic organisms and do not possess membrane-bound organelles like chloroplasts found in eukaryotic cells. Instead, they perform photosynthesis using thylakoids, which are membrane-bound compartments where photosynthesis occurs. Gas vesicles are also present in cyanobacteria and help regulate their buoyancy. Heterocysts are specialized cells that aid in nitrogen fixation, a process that allows cyanobacteria to convert atmospheric nitrogen into a form that can be used by the organism. Therefore, the absence of chloroplasts in cyanobacteria makes choice C the correct answer.

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