Nokea
Which of the following is not required for full activation of a naïve lymphocyte?
- A. Migration into an inflammatory site
- B. Costimulatory signalling
- C. Cytokines
- D. Recognition of specific antigen
Correct Answer: A
Rationale: The correct answer is A. Naïve lymphocytes require activation through recognition of specific antigen, costimulatory signaling, and cytokines. Migration into an inflammatory site is not a requirement for full activation. Naïve lymphocytes can be activated in secondary lymphoid organs where antigen presentation occurs. Migration to inflammatory sites occurs after activation to fight infections.
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Which of the following statements is most correct? Immunoglobulin gene rearrangement:
- A. Occurs after transcription of an immunoglobulin gene
- B. Creates a complete V exon in the germline DNA
- C. Creates a complete V exon in the B cell DNA
- D. Both A and B are correct
Correct Answer: C
Rationale: The correct answer is C because immunoglobulin gene rearrangement creates a complete V exon in the B cell DNA. This process happens during B cell development, where segments of V, D, and J gene regions are rearranged to form a functional immunoglobulin gene. This rearrangement occurs before transcription, so option A is incorrect. Option B is incorrect because the V exon is not complete in the germline DNA, but rather created through rearrangement in the B cell DNA. Option D is incorrect as it combines two incorrect statements.
the characteristic of blood types AB is
- A. a general receptor
- B. a general donor
- C. a receptor and donor
- D. neither donating nor receptor
Correct Answer: A
Rationale: The correct answer is A: a general receptor. Blood type AB individuals have both A and B antigens on their red blood cells, making them universal recipients since they can receive blood from all blood types without rejection. This is because they have no antibodies against A or B antigens. The other choices are incorrect because blood type AB individuals cannot be universal donors (choice B) as they have both A and B antigens, not making them suitable for all recipients. They are not both a receptor and donor (choice C) as they can only receive blood from all types, not donate to all. Lastly, they are not neither donating nor a receptor (choice D) since they can receive blood from all types, making them a receptor.
Which cell type bridges innate and adaptive immunity?
- A. NK cells
- B. Dendritic cells
- C. Plasma cells
- D. Mast cells
Correct Answer: B
Rationale: The correct answer is B: Dendritic cells. Dendritic cells bridge innate and adaptive immunity by capturing antigens, processing them, and presenting them to T cells to initiate adaptive immune responses. NK cells (A) are part of innate immunity, while plasma cells (C) produce antibodies in adaptive immunity. Mast cells (D) are involved in allergic responses, not bridging innate and adaptive immunity.
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.
Identify the disease in which the person's immune system no longer recognizes its own tissues or organs.
- A. Allergies
- B. Immunodeficiencies
- C. Autoimmune diseases
- D. Delayed hypersensitivity
Correct Answer: C
Rationale: The correct answer is C: Autoimmune diseases. This is because autoimmune diseases occur when the immune system mistakenly attacks the body's own tissues or organs. In this condition, the immune system fails to recognize self from non-self, leading to inflammation and tissue damage.
A: Allergies involve an exaggerated immune response to harmless substances, not attacking self-tissues.
B: Immunodeficiencies result in a weakened immune system, making it less effective at fighting infections, not attacking self-tissues.
D: Delayed hypersensitivity is a type of immune response that occurs hours to days after exposure to an allergen, not involving the immune system attacking self-tissues.
In summary, autoimmune diseases are characterized by the immune system targeting the body's own tissues or organs, distinguishing them from allergies, immunodeficiencies, and delayed hypersensitivity.