Nokea
Which of the following is a feature of antigen recognition by B cells?
- A. Their antigen receptors are never secreted
- B. Their antigen receptors recognize a fragment of protein in combination with an MHC molecule
- C. Their receptors each have two identical antigen binding sites
- D. They recognize pattern associated molecular structures (PAMPs) that are unique to a particular pathogen
Correct Answer: C
Rationale: The correct answer is C because B cell receptors, known as antibodies, are Y-shaped proteins with two identical antigen-binding sites. This feature allows B cells to bind to specific antigens with high specificity. Each B cell receptor can bind to a unique antigen, leading to the initiation of an immune response.
Choice A is incorrect because B cell receptors can be secreted as antibodies to target antigens outside the cell.
Choice B is incorrect because B cell receptors recognize antigens directly, not in combination with MHC molecules.
Choice D is incorrect because B cells primarily recognize specific antigens rather than general PAMPs associated with pathogens.
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Which pairing of immune response type and immune response feature is not correct?
- A. Innate: Acts rapidly
- B. Adaptive: Results in memory
- C. Innate: Mediated by lymphocytes
- D. Adaptive: Can distinguish between specific pathogens
Correct Answer: C
Rationale: The correct answer is C because innate immune response is not mediated by lymphocytes. Innate response involves physical barriers, such as skin and mucous membranes, and cells like macrophages and neutrophils. Lymphocytes are part of the adaptive immune response, which is characterized by specificity and memory. Choice A is correct as the innate response acts rapidly due to pre-existing mechanisms. Choice B is correct as adaptive response results in memory cells for quicker response upon re-exposure. Choice D is correct as adaptive response can recognize and respond to specific pathogens through antigen recognition.
What is the primary goal of palliative care in cancer treatment?
- A. Cure the disease
- B. Extend life expectancy
- C. Relieve suffering and improve quality of life
- D. Prevent disease recurrence
Correct Answer: C
Rationale: Palliative care focuses on relieving suffering and improving quality of life for patients with advanced cancer.
Which of the following is not considered a virulence factor?
- A. Flagella
- B. Effector proteins manipulating host actin cytoskeleton
- C. Toxins
- D. Peptidoglycan
Correct Answer: D
Rationale: The correct answer is D: Peptidoglycan. Peptidoglycan is a structural component of bacterial cell walls and does not directly contribute to the pathogenicity or virulence of the bacterium. Flagella aid in motility and colonization, effector proteins manipulate host cells, and toxins damage host tissues, all of which are virulence factors. Peptidoglycan is essential for maintaining cell shape and integrity but does not directly enhance the ability of the bacteria to cause disease.
The epitopes recognized by T cells are always:
- A. Conformational
- B. Linear
- C. On the antigen surface
- D. Buried inside the antigen
Correct Answer: B
Rationale: The correct answer is B: Linear. T cells recognize linear epitopes, which are sequences of amino acids displayed in a linear fashion on the antigen's surface. This recognition occurs through the T cell receptor binding to the linear epitope. Conformational epitopes (A) involve multiple amino acid residues brought together in a specific three-dimensional structure. Epitopes on the antigen surface (C) are correct, but not all T cell epitopes are necessarily on the surface. Epitopes buried inside the antigen (D) are not accessible to T cell receptors for recognition. Thus, the correct choice is B due to the linear presentation of epitopes for T cell recognition.
Which patient would be most likely to be cured with chemotherapy as a treatment measure?
- A. Small cell lung cancer
- B. New neuroblastoma
- C. Small tumor of the bone
- D. Large hepatocellular carcinoma
Correct Answer: B
Rationale: Neuroblastoma, especially in newly diagnosed cases, is highly responsive to chemotherapy and has a higher likelihood of cure.