BIOS 251 Exam 2 Questions and Answers

BIOS 251 Exam 2 Questions and Answers Which of the following would prevent a microbe from activating the Alternative pathway of the compliment system? a) a bacteria that has an enzyme that degrades antibodies b) a bacteria that has a thick cell wall c) a bacteria that can prevent C3b from binding to it d) a bacteria that contain no mannose - ANSWER -c) a bacteria that can prevent C3b from binding to it Which of the following is NOT a feature of the skin that allows it to serve as a barrier to infection? a) melanin in the skin is toxic to a bacteria b) sweat creates a sling environment that prevents non-halotolerant bacteria from growing c) tight junctions in keratinocytes make the skin waterproof d) resident flora produce bacteriocins - ANSWER -a) melanin in the skin is toxic to a bacteria The immune system cell most commonly associated with allergies is: a) neutrophil b) eosinophil c) basophil d) macrophage - ANSWER -c) basophil Which of the following would be an example of a PAMP? a) GaGs on the surface of eukaryotic of a PAMP b) C3b bound to bacteria c) peptidoglycan d) tissue factor - ANSWER -c) peptidoglycan This cytokine is released by virally infected cells, anti-viral - ANSWER -interferon Suppose that someone's blood stem cells in their marrow ware dividing and developing into B cells. What cytokine might be responsible for this? a) chemokines b) tumor necrosis factor c) colony stimulating factor d) interferon - ANSWER -c) colony stimulating factor Which of the following cells would likely have Toll-like receptors (TLRs)? a) mast cells b) dendritic cells c) neutrophils d) T-lymphocytes e) hepatocytes - ANSWER -mast cells, dendritic cells Which of the following would be most likely to be detected by a Rig-like receptor (RLR) a) bacterial DNA b) helminth proteins c) double stranded RNA d) LPS - ANSWER -c) double stranded RNA What event during inflammation is responsible for swelling? a) diapedesis b) increasing vascular permeability c) vasodilation d) increased sensitivity of nociceptors - ANSWER -b) increasing vascular permeability Put the steps of Phagocytosis in order. Chemotaxis Exocytosis Recognition and Attachment Engulfment (endocytosis) Destruction and Digestion Phagosome maturation and phagolysosome formation - ANSWER -Chemotaxis Recognition and Attachment Engulfment (endocytosis) Phagosome maturation and phagolysosome formation Destruction and Digestion Exocytosis What are examples of Antigen Presenting Cells? - ANSWER -Mast cells, Dendritic cells, Macrophages, B-cells Which of the following is NOT a way that antibodies assist the immune system in getting rid of pathogens? a) labelling pathogens for phagocytosis (opsonization) b) poking holes in the cell membrane and lysing bacteria directly c) binding to viral coat proteins and preventing them from being able to enter cells d) binding to flagella and fimbrae and preventing movement and adherence - ANSWER -b) poking holes in the cell membrane and lysing bacteria directly Which of the following pathogens could initiate an antibody response without Helper Tcells? a) HIV b) Gram- organisms c) Gram+ organisms d) Helper T-cells are not normally for an antibody response - ANSWER -b) Gramorganisms Which of the following statements about B-cells is false? a) B-cells mature in the bone marrow b) B-cell receptors are all identical c) When activated, B-cells differentiate into plasma cells d) B-cells present foreign antigens on an MHCII - ANSWER -b) B-cell receptors are all identical Suppose you are observing a patient who has a bacterial infection that begins to subside fairly quickly after becoming symptomatic. An analysis of their blood shows high levels of IgM specific to the bacteria, but undetectable levels of IgG and IgD. Two months after being discharged, the patient returns with another infection by the same bacteria. What would be reasonable to conclude? - ANSWER -The patient's immune reaction happened through the T-independent pathway Know the following: IgM, IgG, IgA, IgE, IgD - ANSWER -IgM- first antibody produced in response to an infection IgG- antibody that penetrates the placenta; abundant in blood and fluids; antibody of memory IgA- found in body secretions: mucus, tears, saliva, breastmilk for infants IgE- involved in allergic reactions IgD- poorly understood function Suppose that an antibody binds to a toxin molecule and prevents the toxin from binding to a receptor where it would have a negative effect. This is an example of: a) cross-linking b) opsonization c) immobilization d) neutralization - ANSWER -d) neutralization In the thymus, T-cells that bind self antigens are: a) stimulated to proliferate (divide) b) sent to the spleen c) eliminated through negative selection d) shunted back into the thymus for a second round of selection - ANSWER -c) eliminated through negative selection An HIV positive individual with low CD4 T-cell count is infected with a normally nonfatal virus and later dies. What likely occurred? a) they were unable to release histamine and could don't mount an inflammatory response b) their immune system became hyper-active through the T-independent pathway and they died due to a cytokine storm c) they were unable to generate antibodies through the T-dependent pathway due to lack of helper T-cells