Bio 400 Exam Questions With All Correct Answers Verified Answers 2025 Marking Scheme New Update

Bio 400 Exam Questions With All Correct Answers Verified Answers 2025 Marking Scheme New Update define the term antigen - Answer- any substance recognized by the immune system identify the barriers that help prevent microbial invasion of the host - Answer- physical and chemical explain how the physical and mechanical barriers function to prevent microbial invasion of the host - Answer- physical: skin, mucus membrane (trap and destroy pathogens and have antimicrobial peptides), respiratory system, stomach (low ph), intestines (have pancreatic enzymes and normal microbiota), GI tract (flush system) chemical: found in secretions relate host anatomy and secretions to the success of innate resistance strategies - Answer- tears, mucus, breast milk differentiate between lysozyme, lactoferrin, and lactoperoxidase - Answer- - lysozyme: enzyme that cuts glycosidic bond between NAG-NAM within petidoglycan (cell wall) - lactoferrin: sequesters iron (iron grows bacteria) - lactoperoxidase: catalyzes production of superoxide radicals toxic to microbes define defensins and their function - Answer- antimicrobial peptides that destroy invaders of the cell membrane, are small and cationic describe in general terms the activation of the host alternative complement system and its three outcomes - Answer- the cascade is activated in the presence of a pathogen; 1) increase inflammation, 2) lyse pathogen, 3)increase phagocytosis identify the complement proteins involved in the process - Answer- - once C3 is cleaved LPS binds to C3b which binds to other components of the cascade and forms C3 convertase - C3 convertase cleaves C3 which increase production of C3b and C3a - C3a is chemoattractant that floats away and attracts immune cells and C3b cleaves C5 - C5 convertase cleaves C5a and C5b, then C5a floats away and C5b forms membrane attack complex - C6,C7,C8,C9 are the membrane attack complex that lyse the pathogen recognize the different types of leukocytes involved with innate resistance and their major function in the innate system - Answer- - leukocytes are white blood cells - respond to local trauma in tissues - circulate in body fluids and recruit to sites of infection after alarm mast cells, basophils, neutrophils, eosinophils - Answer- - mast cells: differentiate in connective tissue, contain granules with histamine and prostaglandins (allergy response) - basophils: contain histamines (allergy response) - neutrophils: major phagocyte of cell that don't present antigen - eosinophils: defend against protozoan and helminth parasites define antigen presenting cells - Answer- take pieces of bacteria and present to adaptive immune response (macrophages and dendritic cells) explain function of natural killer cells - Answer- destroy virally infected and cancerous host cells; recognize targets that are covered in antibodies, no longer express MHC1, and have granzymes and perforin explain the function of skin- and mucosal-associates lymphoid tissues - Answer- - skin has specialized cells, M cells, MALT, GALT, BALT, and lagerhans (dendritic cells) - spleen filters blood and traps blood borne particles for assessment by phagocytes and B cells - lymph nodes filter lymph and are rich in B cells and inner region T cells explain the methods by which pathogens are recognized by phagocytes - Answer- pattern recognition receptors and MAMPS explain the difference difference between MAMPS/PRPS - Answer- - MAMPS bind to TLRs then signal is sent to the nucleus to induce cytokine synthesis and can be recognized by PRPs - PRPs are toll-like/ NOD-like receptors (TLR and NLR) explain the process of phagocytosis - Answer- - the bacteria is engulfed by the cell and the phagosome is fuse with the lysosome - macrophages and neutrophils recognize the surface of the particle as foreign but CD47 will prevent self attack - pathogens w capsule prevent phagocytosis and opsonins enhance it outline the steps of inflammation - Answer- - infection releases microbes to the tissue - resident macrophages recognize MAMPS release cytokines and phagocytize the bacteria - IL-1 abd TNF-alpha cause capillary cells to express selectins - neutrophils then express integrins on their surface and extravasate (squeeze btw capillary cells) explain how the innate system helps protect against pathogens and how this is different than the adaptive arm - Answer- innate has nonspecific response to destroy invading cells where as the adaptive arm reacts to specific antigens contrast host innate resistance w adaptive immunity - Answer- - innate response is within hours and adaptive is within days - innate has no memory - innate is first response and present at birth - adaptive is activated by cells and chemicals of innate immune system define 2 branches of adaptive immunity by their cell types and general function - Answer- - cell mediated: t cells - antibody-mediated immunity: B cells predict the types of molecules that can serve as antigens - Answer- proteins, carbs, nucleic acids, and lipids explain why proteins are the best antigens - Answer- 3D structure is complex epitope - Answer- compose an antigen; different sites that elicit an immune response compare and contrast methods by which immunity occurs by natural and artificial means - Answer- both are active and passive - natural by normal life experiences - artificial by medical procedures list examples of natural active, natural passive, artificial active, artificial passive immunity - Answer- NA: fighting sickness NP: breastfeeding AA: vaccine PI: immune globulin therapy compare the processes by which MHC class 1 and class 2 receptors recognize foreignness - Answer- - both have transmembrane anchor and extracellular domain w multiple subunits explain which cells possess MH1 and/or 2 molecules - Answer- - MHC1 found on all nucleated cells -MHC2 expressed on macrophages and dendritic cells endogenous/exogenous antigens - Answer- - endogenous: infected, class 1 binds to antigen peptides that originate in the cytoplasm and present antigen to CD8+ cells - exogenous: extracellular pathogens, class 2 binds to antigen fragments that come from outside the cell and present to CD4+ t-helper cells identify cells that function as antigen-presenting (APCs) - Answer- dendritic cells