Q.1 Which organ is the primary site for T cell maturation?
Bone marrow
Thymus
Spleen
Lymph nodes
Explanation - T cells originate from hematopoietic stem cells in the bone marrow but mature in the thymus, where they undergo positive and negative selection.
Correct answer is: Thymus
Q.2 Where do B cells mature in humans?
Thymus
Bone marrow
Lymph nodes
Spleen
Explanation - B cells mature in the bone marrow, undergoing processes like V(D)J recombination to develop their unique antigen receptors.
Correct answer is: Bone marrow
Q.3 Which transcription factor is critical for T cell lineage commitment?
GATA3
FOXP3
Notch1
BCL6
Explanation - Notch1 signaling drives progenitor cells in the thymus to commit to the T cell lineage instead of other hematopoietic lineages.
Correct answer is: Notch1
Q.4 During fetal development, the liver primarily functions as a site for which immune cells?
T cells
B cells
Macrophages
Hematopoietic stem cells
Explanation - The fetal liver is the main site of hematopoiesis before the bone marrow becomes the primary site after birth.
Correct answer is: Hematopoietic stem cells
Q.5 Which of the following is a secondary lymphoid organ?
Bone marrow
Thymus
Spleen
Fetal liver
Explanation - Secondary lymphoid organs like the spleen and lymph nodes are sites where mature lymphocytes encounter antigens and initiate immune responses.
Correct answer is: Spleen
Q.6 What is the main function of the thymic epithelial cells?
Produce antibodies
Support T cell maturation
Present antigens to B cells
Stimulate macrophage differentiation
Explanation - Thymic epithelial cells provide the necessary environment and signals for T cell development and selection in the thymus.
Correct answer is: Support T cell maturation
Q.7 Which signal is necessary for the survival of immature B cells in the bone marrow?
IL-7
TNF-alpha
IFN-gamma
TGF-beta
Explanation - Interleukin-7 (IL-7) is crucial for the proliferation and survival of immature B and T cells during development.
Correct answer is: IL-7
Q.8 Positive selection in the thymus ensures that T cells can:
Recognize self-MHC molecules
Avoid self-antigens
Mature into B cells
Secrete antibodies
Explanation - Positive selection allows thymocytes that can recognize self-MHC molecules to survive, ensuring functional T cell responses.
Correct answer is: Recognize self-MHC molecules
Q.9 Negative selection in the thymus eliminates T cells that:
Fail to bind antigens
Bind strongly to self-antigens
Migrate to the spleen
Produce antibodies
Explanation - Negative selection removes autoreactive T cells to prevent autoimmune reactions.
Correct answer is: Bind strongly to self-antigens
Q.10 Which cells present self-antigens to developing T cells in the thymus for negative selection?
Thymic epithelial cells
Dendritic cells
Macrophages
All of the above
Explanation - Thymic epithelial cells, dendritic cells, and macrophages present self-antigens to developing T cells to eliminate autoreactive clones.
Correct answer is: All of the above
Q.11 Which factor is essential for the development of regulatory T cells (Tregs)?
FOXP3
GATA3
BCL-6
RORγt
Explanation - FOXP3 is a transcription factor critical for the differentiation and function of regulatory T cells, which maintain immune tolerance.
Correct answer is: FOXP3
Q.12 Secondary lymphoid tissues are organized to maximize:
Cell proliferation
Antigen encounter by lymphocytes
Apoptosis of immune cells
Cytokine degradation
Explanation - Secondary lymphoid organs like lymph nodes and spleen are structured to bring antigens and lymphocytes together efficiently.
Correct answer is: Antigen encounter by lymphocytes
Q.13 Which chemokine receptor guides T cells to the thymus?
CCR7
CXCR4
CCR9
CXCR5
Explanation - CCR9 directs T cell precursors from the bone marrow to the thymus, facilitating proper T cell development.
Correct answer is: CCR9
Q.14 Hematopoietic stem cells are primarily found in which adult tissue?
Spleen
Bone marrow
Thymus
Liver
Explanation - In adults, hematopoietic stem cells reside mainly in the bone marrow, giving rise to all blood and immune cell lineages.
Correct answer is: Bone marrow
Q.15 Which is the earliest lymphoid progenitor that can give rise to both B and T cells?
Common myeloid progenitor
Common lymphoid progenitor
Hematopoietic stem cell
Megakaryocyte progenitor
Explanation - Common lymphoid progenitors differentiate into T cells, B cells, NK cells, and some dendritic cells.
Correct answer is: Common lymphoid progenitor
Q.16 The spleen filters blood primarily to remove:
T cells
B cells
Old red blood cells and antigens
Platelets only
Explanation - The spleen filters blood, removing senescent red blood cells and blood-borne pathogens, while also serving as a site for immune responses.
Correct answer is: Old red blood cells and antigens
Q.17 Which cytokine is most critical for early lymphoid development in the bone marrow?
IL-2
IL-7
IL-12
IL-10
Explanation - IL-7 is essential for early lymphocyte development, promoting survival and proliferation of lymphoid progenitors.
Correct answer is: IL-7
Q.18 Which cell type is responsible for antigen presentation in the thymus during negative selection?
Erythrocytes
Macrophages
T cells
NK cells
Explanation - Macrophages and dendritic cells present self-antigens to thymocytes, ensuring self-reactive T cells are deleted.
Correct answer is: Macrophages
Q.19 The bone marrow is a site of central tolerance for which cell type?
T cells
B cells
NK cells
Macrophages
Explanation - In the bone marrow, immature B cells that recognize self-antigens are either eliminated or undergo receptor editing to prevent autoimmunity.
Correct answer is: B cells
Q.20 Which organ shrinks (involutes) with age, reducing T cell output?
Bone marrow
Thymus
Spleen
Lymph nodes
Explanation - The thymus gradually involutes after puberty, leading to reduced production of new naive T cells in adults.
Correct answer is: Thymus
Q.21 NK cells arise from which progenitor lineage?
Common lymphoid progenitor
Common myeloid progenitor
Megakaryocyte progenitor
Erythroid progenitor
Explanation - Natural killer (NK) cells develop from the common lymphoid progenitor, like T and B cells, but do not undergo receptor rearrangement.
Correct answer is: Common lymphoid progenitor
Q.22 Which organ is responsible for initiating immune responses to antigens in the blood?
Thymus
Bone marrow
Spleen
Lymph nodes
Explanation - The spleen monitors the blood for pathogens and mounts immune responses, especially against blood-borne antigens.
Correct answer is: Spleen
Q.23 Which of the following is NOT a function of secondary lymphoid organs?
Lymphocyte activation
Antigen filtration
Lymphocyte maturation
Immune response initiation
Explanation - Secondary lymphoid organs primarily activate mature lymphocytes and filter antigens; maturation occurs in primary lymphoid organs.
Correct answer is: Lymphocyte maturation
Q.24 Which developmental process ensures diversity of antigen receptors in B and T cells?
Positive selection
Negative selection
V(D)J recombination
Clonal expansion
Explanation - V(D)J recombination randomly assembles gene segments to generate diverse antigen receptor repertoires in B and T cells.
Correct answer is: V(D)J recombination
Q.25 Which cell type bridges the innate and adaptive immune system during development?
Macrophages
Dendritic cells
Erythrocytes
Platelets
Explanation - Dendritic cells capture antigens and present them to T cells, linking innate recognition to adaptive immune activation.
Correct answer is: Dendritic cells