Free LST Antigen Questions and Answers — Questions and Answers
Question 1: What is the primary function of lymphocytes in the immune system?
- Fight infections and provide immunity (Correct answer)
- Produce red blood cells
- Transport oxygen
- Regulate blood pressure
Correct answer: Fight infections and provide immunity
Lymphocytes are a type of white blood cell that plays a critical role in the immune response by fighting infections and providing immunity.
Question 2: What are the main types of lymphocytes involved in antigen recognition?
- T cells and B cells (Correct answer)
- Erythrocytes and leukocytes
- Platelets and monocytes
- Neutrophils and basophils
Correct answer: T cells and B cells
T cells and B cells are the primary lymphocytes involved in antigen recognition and immune response.
Question 3: What molecule on the surface of B cells is responsible for antigen recognition?
- B cell receptor (BCR) (Correct answer)
- T cell receptor (TCR)
- Major histocompatibility complex (MHC)
- Complement proteins
Correct answer: B cell receptor (BCR)
The B cell receptor (BCR) on the surface of B cells binds to specific antigens, initiating the immune response.
Question 4: What is the role of T cell receptors (TCRs) in antigen recognition?
- They bind to antigens presented by MHC molecules on antigen-presenting cells (Correct answer)
- They produce antibodies
- They phagocytize pathogens
- They release histamine
Correct answer: They bind to antigens presented by MHC molecules on antigen-presenting cells
T cell receptors (TCRs) on T cells recognize and bind to antigens presented by MHC molecules on the surface of antigen-presenting cells.
Question 5: Which type of MHC molecule presents endogenous antigens to CD8+ T cells?
- MHC class II
- MHC class I (Correct answer)
- MHC class III
- MHC class IV
Correct answer: MHC class I
MHC class I molecules present endogenous antigens (from within the cell) to CD8+ cytotoxic T cells.
Question 6: What type of antigens do MHC class II molecules present?
- Exogenous antigens (Correct answer)
- Self-antigens
- Endogenous antigens
- Viral antigens
Correct answer: Exogenous antigens
MHC class II molecules present exogenous antigens (from outside the cell) to CD4+ helper T cells.
Question 7: What is the initial event in the lymphocyte activation process?
- Recognition of an antigen by a specific receptor on the lymphocyte (Correct answer)
- Proliferation of lymphocytes
- Release of antibodies
- Migration to the site of infection
Correct answer: Recognition of an antigen by a specific receptor on the lymphocyte
The initial event in lymphocyte activation is the recognition of an antigen by a specific receptor on the lymphocyte.
Question 8: What is clonal expansion in the context of lymphocyte activation?
- Rapid proliferation of lymphocytes that have recognized a specific antigen (Correct answer)
- Differentiation into various cell types
- Secretion of cytokines
- Phagocytosis of pathogens
Correct answer: Rapid proliferation of lymphocytes that have recognized a specific antigen
Clonal expansion is the process by which lymphocytes that have recognized a specific antigen rapidly proliferate to mount an effective immune response.
Question 9: Which cells are considered professional antigen-presenting cells (APCs)?
- Dendritic cells, macrophages, and B cells (Correct answer)
- Red blood cells and platelets
- Neutrophils and eosinophils
- Basophils and mast cells
Correct answer: Dendritic cells, macrophages, and B cells
Dendritic cells, macrophages, and B cells are professional antigen-presenting cells that process and present antigens to T cells.
Question 10: What cytokine is essential for the proliferation of activated T cells?
- Interleukin-2 (IL-2) (Correct answer)
- Interleukin-1 (IL-1)
- Interleukin-4 (IL-4)
- Interferon-gamma (IFN-γ)
Correct answer: Interleukin-2 (IL-2)
Interleukin-2 (IL-2) is a cytokine that is crucial for the proliferation and survival of activated T cells.
Question 11: How do cytotoxic T cells kill infected cells?
- By secreting perforin and granzymes that induce apoptosis (Correct answer)
- By phagocytosis
- By releasing antibodies
- By producing histamine
Correct answer: By secreting perforin and granzymes that induce apoptosis
Cytotoxic T cells kill infected cells by secreting perforin and granzymes, which induce apoptosis in the target cells.
Free LST Antigen Questions and Answers
What is the primary function of lymphocytes in the immune system?