Week 1 Assignment PDF

Week 1 Assignment 1. Hematopoietic stem cells originate in _______. a) Bone marrow b) Spleen c) Liver d) Fetal tissues Answer: (d) Explanation: HSCs originate in fetal tissues and reside primarily in the bone marrow of adult vertebrates. A small number can be found in the...

Week 1 Assignment 1. Hematopoietic stem cells originate in _______. a) Bone marrow b) Spleen c) Liver d) Fetal tissues Answer: (d) Explanation: HSCs originate in fetal tissues and reside primarily in the bone marrow of adult vertebrates. A small number can be found in the adult spleen and liver. 2. Lymphoid progenitor cells do not give rise to which of the following cells? a) Dendritic cells b) B- lymphocytes c) Granulocytes d) All of the above Answer: (c) Explanation: Lymphoid progenitor cell gives rise to B lymphocytes, T lymphocytes, innate lymphoid cells (ILCs), and specific dendritic cell populations. 3. Which of the following cells form the innate immune system? a) B cells and T cells b) Macrophages and NK cells c) Both a and b d) None of the above Answer: (b) Explanation: Innate immunity is our first active line of defence and includes monocytes/macrophages, neutrophils, dendritic cells (DCs), plasma proteins (as complements and collectins), endothelial cells, and natural killer cells (NK cells). 4. Match the type of cells with their functions: Cells Function i) Macrophage i) Killing of antibody-coated parasites. ii) Dendritic cells ii) Antigen presentation iii) Neutrophils iii) Phagocytosis and activation of iv) Basophil bactericidal mechanisms v) Eosinophil iv) Antigen uptake in peripheral sites vi) Mast cell v) Release of granules containing histamine and active agent. vi) Promotion of allergic responses and augmentation of anti- parasitic immunity. a) i-ii; ii-i,iii; iii- v; iv-vi; v- iv; vi-iii b) i-ii,iii; ii-ii,iv; iii-iii; iv-vi; v-i; vi-v c) i-ii; ii-ii,iv; iii-iii,ii; iv-vi; v-i; vi-v d) i-ii,iii; ii-ii,iv; iii-vi; iv-iii; v-I; vi-v Answer: (b) 5. What is the function of Regulatory T cells? a) To kill other cells that are infected with viruses or other intracellular pathogens bearing the antigen. b) To provide signals, often in the form of specific cytokines that activate the functions of other cells. c) To suppress the activity of other lymphocytes and help to limit the possible damage of immune responses. d) All of the above. Answer: (c) 6. Circulating Lymphocytes encounter antigens in _______. a) Primary Lymphoid organs b) Peripheral Lymphoid organs c) Both a and b d) None of the above. Answer: (b) Explanation: Naive lymphocytes recirculate constantly through peripheral lymphoid tissue where lymphocytes may encounter their specific antigens and become activated. 7. Which cells are present in the marginal zone of the spleen? a) T- cells b) B- cells c) Macrophages d) All of the above. Answer: (d) Explanation: The marginal zone has few T cells, is rich in macrophages, and has a resident, noncirculating population of B cells known as marginal zone B cells. 8. Peyer’s patches are a part of _______. a) GALT b) MALT c) BALT d) NALT Answer: (a) Explanation: The gut-associated lymphoid tissues (GALT) include the tonsils, adenoids, appendix, and specialized structures in the small intestine called Peyer’s patches. 9. Identify the correct sequence of events. a) Antigen presentation by APC  recognition of antigen by lymphocyte  differentiation into lymphoblast  division into daughter cells with identical specificity  differentiation into effector cells. b) Antigen presentation by APC  recognition of antigen by lymphocyte division into daughter cells with identical specificity  differentiation into effector cells differentiation into lymphoblast. c) Recognition of antigen by lymphocyte Antigen presentation by APC  division into daughter cells with identical specificity  differentiation into effector cells differentiation into lymphoblast. d) Differentiation into lymphoblast antigen presentation by APC  recognition of antigen by lymphocyte  division into daughter cells with identical specificity  differentiation into effector cells. Answer: (a) Explanation: On recognizing its specific antigen on an activated antigen-presenting cell, a naive lymphocyte stops migrating, the volume of the nucleus and cytoplasm increases, and new mRNAs and new proteins are synthesized. Within a few hours, the cell looks completely different and is known as a lymphoblast. Dividing lymphoblasts are able to duplicate themselves two to four times every 24 hours for 3–5 days, so that a single naive lymphocyte can produce a clone of around 1000 daughter cells of identical specificity. These then differentiate into effector cells. 10. B cells mature into antibody-producing cells in _______. a) B- cell corona b) Marginal zone c) Germinal centers d) Red pulp Answer: (c) Explanation: Activated B cells undergo further maturation into high-affinity, antibody- producing cells in specialized microenvironments called germinal centers, substructures that develop within B-cell follicles.