Nokea
Individuals unable to make the J protein found in certain immunoglobulins would be expected to have frequent infections of the
- A. intestinal tract
- B. blood.
- C. liver.
- D. pancreas.
Correct Answer: A
Rationale: The correct answer is A: intestinal tract. The J protein is crucial for the proper functioning of immunoglobulins in the mucosal immune system, which plays a major role in defending against pathogens in the intestinal tract. Without the J protein, individuals would have impaired immune responses in the gut, leading to frequent infections in the intestinal tract. Choices B, C, and D are incorrect because the J protein deficiency specifically affects the mucosal immune system in the intestinal tract, not the blood, liver, or pancreas.
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Identify the option that represents the correct order of events in naïve T cell activation:
- A. Entry into the site of infection, antigen recognition, clonal expansion
- B. Antigen recognition, clonal expansion, entry into the site of infection
- C. Entry into the site of infection, clonal expansion, antigen recognition
- D. Antigen recognition, entry into the site of infection, clonal expansion
Correct Answer: B
Rationale: The correct order of events in naïve T cell activation is: antigen recognition, clonal expansion, entry into the site of infection. First, T cells must recognize the specific antigen presented by antigen-presenting cells. This recognition triggers clonal expansion, where T cells proliferate and differentiate into effector cells. Finally, the activated T cells migrate to the site of infection to combat the pathogen. Option B is correct because it follows this sequential order. Options A, C, and D are incorrect because they do not adhere to the correct sequence of events in naïve T cell activation.
Lymph consists of fluid that:
- A. Is taken up from tissues by lymphatic capillaries
- B. Carries antigens and mature dendritic cells to lymph nodes
- C. Is secreted by lymphocytes
- D. Two of these options are correct
Correct Answer: D
Rationale: Rationale:
1. A is correct as lymph is taken up from tissues by lymphatic capillaries.
2. B is correct as lymph carries antigens and mature dendritic cells to lymph nodes.
3. C is incorrect as lymph is not secreted by lymphocytes.
4. Therefore, D is correct as both A and B accurately describe the components and functions of lymph.
Which of the following is NOT an example of a pathogen-associated molecular pattern (PAMP)?
- A. Lipopolysaccharide (LPS)
- B. Peptidoglycan
- C. Viral RNA
- D. MHC molecules
Correct Answer: D
Rationale: The correct answer is D, MHC molecules. PAMPs are conserved molecules found on pathogens that can trigger an immune response. MHC molecules are not PAMPs; they are part of the host's immune system used to present antigens to T cells. LPS, peptidoglycan, and viral RNA are examples of PAMPs as they are specific molecules found on pathogens that can be recognized by pattern recognition receptors on immune cells to initiate an immune response.
What is the structural composition of an antibody?
- A. Two heavy chains and two light chains
- B. Three heavy chains and one light chain
- C. Two heavy chains and three light chains
- D. Four heavy chains
Correct Answer: A
Rationale: The correct answer is A: Two heavy chains and two light chains. Antibodies are composed of two identical heavy chains and two identical light chains. Heavy chains provide structural support and effector functions, while light chains contribute to antigen binding. Choice B is incorrect as antibodies do not have three heavy chains. Choice C is incorrect as antibodies do not have three light chains. Choice D is incorrect as antibodies do not have four heavy chains.
The membrane of gas vesicles is composed of:
- A. triglycerides
- B. phospholipids
- C. proteins
- D. lipopolysaccharide
Correct Answer: C
Rationale: The correct answer is C: proteins. Gas vesicles are gas-filled structures found in certain bacteria and archaea to provide buoyancy. The membrane of gas vesicles is predominantly composed of proteins that form a semi-permeable barrier to trap gas. Proteins are essential for the structure and function of gas vesicles. Triglycerides (A) are not typically found in membrane structures, phospholipids (B) are more common in cell membranes, and lipopolysaccharides (D) are typically found in the outer membrane of Gram-negative bacteria, not in gas vesicle membranes.