Immune System Quizlet

Immune System Quizlet Related

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In the late 1890s, 'cellularists' and 'humoralists' were intensively arguing about the key components driving the immune response. What was a crucial finding that led the humoralists to dominate the field in the following 50 years?

  • A. The demonstration of the Germ Theory of disease
  • B. The discovery that cell-free serum could transfer immunity from an immunized animal to a non-immunized one
  • C. The discovery of the tuberculin reaction
  • D. The determination of the antibody structure
Correct Answer: B

Rationale: The correct answer is B, the discovery that cell-free serum could transfer immunity. This finding led humoralists to dominate because it supported the idea of circulating antibodies in the serum being responsible for immunity. This concept aligned with the humoralist theory, which focused on the role of antibodies in immune response. The ability of cell-free serum to transfer immunity provided direct evidence for humoralists' beliefs.

Choice A (The demonstration of the Germ Theory of disease) is incorrect because while it was a significant advancement in understanding disease, it did not directly impact the argument between cellularists and humoralists regarding the immune response.

Choice C (The discovery of the tuberculin reaction) is incorrect as it was more relevant to the understanding of the immune response to tuberculosis specifically, rather than the broader debate between cellularists and humoralists.

Choice D (The determination of the antibody structure) is incorrect because while understanding antibody structure is crucial, it did not have as direct an impact on the dominance of

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Which of the following is a primary lymphoid organ?

  • A. Spleen
  • B. Thymus
  • C. Lymph node
  • D. Mucosal immune system
Correct Answer: B

Rationale: The correct answer is B: Thymus. The thymus is considered a primary lymphoid organ because it is where T lymphocytes (T cells) mature and differentiate. T cells play a crucial role in the adaptive immune response. The thymus is responsible for educating T cells to recognize self versus non-self antigens.

Summary:
A: Spleen is a secondary lymphoid organ involved in filtering blood and producing antibodies, not where T cells mature.
C: Lymph node is also a secondary lymphoid organ where immune cells interact but not where T cells mature.
D: Mucosal immune system refers to the immune system in mucosal tissues, not a specific primary lymphoid organ.

Identify the correct statement(s). In eukaryotic microorganisms:

  • A. mRNA is short-lived (minutes).
  • B. a single, circular chromosome is present.
  • C. 5s, 16s, and 23s ribosomal RNA's are present.
  • D. extrachromosomal DNA can be present.
Correct Answer: D

Rationale: The correct answer is D because extrachromosomal DNA, such as plasmids, can be present in eukaryotic microorganisms. This is true for certain organisms like yeast and some fungi. These DNA molecules are separate from the main chromosomal DNA and can carry additional genetic information.

A: mRNA in eukaryotic microorganisms is not short-lived; it can have varying lifespans depending on the specific mRNA molecule and cellular conditions.
B: Eukaryotic microorganisms typically have multiple linear chromosomes, not a single circular chromosome.
C: While 5s, 16s, and 23s ribosomal RNAs are present in prokaryotic organisms, eukaryotic microorganisms have different types of ribosomal RNA subunits.

A naïve lymphocyte:

  • A. Does not yet express antigen receptors
  • B. Is not yet considered mature
  • C. Has not yet been activated by antigen
  • D. Is found only in primary lymphoid tissues
Correct Answer: C

Rationale: Step-by-step rationale:
1. Naïve lymphocytes have antigen receptors but have not been activated by antigen.
2. Activation is necessary for their differentiation into effector cells.
3. Naïve lymphocytes are considered mature as they have completed development.
4. They circulate in secondary lymphoid tissues, not just primary lymphoid tissues.

Summary:
Choice C is correct because naïve lymphocytes have antigen receptors but have not been activated by antigen. Choices A, B, and D are incorrect because naïve lymphocytes do express antigen receptors, are considered mature, and can be found in both primary and secondary lymphoid tissues.

Which group(s) of microorganisms is (are) thought to be the oldest living organisms?

  • A. eukaryotes
  • B. heterotrophic prokaryotes
  • C. Archaea
  • D. viruses
Correct Answer: C

Rationale: The correct answer is C: Archaea. Archaea are thought to be the oldest living organisms due to their unique characteristics and genetic similarities to the earliest forms of life. They are known for thriving in extreme environments, resembling conditions on early Earth. Other choices are incorrect because eukaryotes are more complex and evolved later, heterotrophic prokaryotes came after autotrophic prokaryotes, and viruses are not considered living organisms.

Which of the following complement proteins is not part of the membrane attack complex?

  • A. C5a
  • B. C5b
  • C. C6
  • D. C7
Correct Answer: A

Rationale: The correct answer is A: C5a. C5a is not part of the membrane attack complex (MAC). The MAC consists of C5b, C6, C7, C8, and multiple C9 molecules. C5a is a chemotactic factor that attracts immune cells to the site of infection, while C5b initiates the formation of the MAC. Choices B, C, and D (C5b, C6, C7) are all components of the MAC and play crucial roles in the formation and function of the complex.

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