immune 10 mylab HW
_______________ describes a set of defenses that is customized to each infectious agent, providing a stronger response when an agent has been encountered before.
Adaptive system
Which secretion is not a barrier that prevents pathogens from entering the body?
Antigens Antigens are foreign molecules that initiate an immune response.
Which of the following statements about the clonal-selection theory of immune system function is false?
Antigens are recognized by receptor proteins inside the lymphocyte. This statement is false; antigens are recognized by receptor proteins on the lymphocyte membrane.
How are cytotoxic T lymphocytes (CTLs) produced?
CD8+ T cells divide and differentiate into cytotoxic T lymphocytes. CD8+ T cells divide and differentiate into a clone of cytotoxic T lymphocytes.
Can you correctly fill in this table that summarizes different kinds of immune system cells?
Cell type: Function a. B cells: secrete antibodies b. helper T cells: stimulate other immune cells c. cytotoxic T cells: destroy body cells that have been infected d. macrophages: engulf pathogens e. antigen-presenting cells: display self-nonself complexes on their surfaces
Select the correct statement about clonal selection.
Clonal selection allows the immune system to combat a wide range of invaders, while being able to mount a specific attack against one invader. You have millions of different B cells. Activating the lines of B cells that respond strongly to a specific threat allows a targeted defense against a specific invader.
What is the final step in the cell-mediated response to a viral infection?
Cytotoxic T lymphocytes punch holes in the membranes of infected host cells. This step causes infected host cells to disintegrate and prevents the virus from spreading to other cells.
True or false? The leukocytes of the innate immune system are B cells, macrophages, and neutrophils.
False The leukocytes of the innate immune system are mast cells, macrophages, and neutrophils.
Which of the following statements best describes the role of mast cells in the inflammatory response?
They release chemicals that dilate blood vessels near the wound site, allowing blood components to enter the region from the bloodstream. Mast cells release chemicals that dilate nearby capillaries, increasing their permeability and allowing blood components to enter the region from the bloodstream, thus causing localized swelling.
The site of inflammation may become swollen due to the increased numbers of cells and fluids at the site and painful due to signals from pain receptors.
True The site of inflammation may also become red due to increased blood flow at the site; the inflammatory response continues until all invaders are eliminated and the wound is repaired.
B cells are involved in the humoral immune response. The flowchart below summarizes the steps involved in B cell activation.
a. antigen-preseting cell presents antigen on class 2 MHC b. helper T cell recognizes antigen using TCR and CD4 c. helper T cell binds to B cell and releases cytokines d. B cell presents antigen on class 2 MHC molecule e. B cell differentiates into plasma cells and memory cells f. plasma cells secrete antibodies
Cytotoxic T cells are the effector cells in the cell-mediated immune response. The diagram below summarizes the interaction of a cytotoxic T cell and its target cell.
a. cytotoxic T cell b. infected cell step 1 c. recognizes cell using TCR and CDB d. presents antigen on class 1 MHC step 2 e. releases perforin and granzymes f. undergoes enzyme attack step 3 g. moves on to destroy another cell h. undergoes apoptosis
Extracellular pathogens such as viruses and bacteria in body fluids are attacked by _____.
antibodies from plasma cells Antibodies are part of the "humoral" immune responses. Circulating antibodies encounter microorganisms in body fluids and complex with them to "mark" them for further counterattack. Return to Assignment
Pathogens have ________ on their surface that bind to B cells with complementary ____________.
antigens; receptors
The role of active cytotoxic T cells is to attack
body cells that have been infected Nonspecific defense includes natural killer cells that destroy virus-infected body cells, and abnormal cells that could form tumors. Cytotoxic (killer) T lymphocytes kill cancer cells and cells infected by viruses or other intracellular pathogens.
Is this statement supported or not supported by the graph? A third exposure to antigen X will produce an even stronger immune response than the second exposure did. https://session.masteringbiology.com/problemAsset/1326599/13/MB_1326599_001.jpg
cannot be determined from the graph
Helper T cells are part of _____.
cell-mediated immune responses Cell-mediated immunity depends on the activation of T lymphocytes.
Innate immunity and acquired immunity are both
characteristics of all vertebrate animals Only vertebrate animals have fully developed acquired immunity to supplement their innate immunity.
B cells that bind to the pathogen divide, forming _________ of identical cells with the same antigen ________.
clones; receptors
Some cells of the clone develop into short-lived ___________ that secrete specific ___________ for the antigen.
effector cells; antibodies
Acquired immunity involves both a humoral immune response and a cell-mediated immune response. To review the definitions of these immune responses, see Hint 1.
humoral response - B cells - plasma cells - antibodies cell-mediated response - cytotoxic T cells both - antigen-presenting cells - memory cells - helper T cells and cytokines
The __________________ is a collection of cells and organs that protect an organism's body from agents that can cause disease.
immune system
An antigen ____________.
is a foreign molecule that evokes a specific response by a lymphocyte Antigen molecules can be a part of any type of organism. Antigen molecules could also be a part of a product of an organism such as pollen or feces.
Macrophages are ________.
large, phagocytic cells that can leave the circulation and enter the tissues of the body Once resident in the tissues, macrophages are active phagocytes that capture and digest many microorganisms.
Which of the following cells can engulf a pathogen?
macrophages Macrophages are leukocytes that can engulf and digest a pathogen.
Some cells develop into long-lived ______________, which produce larger ___________ of memory and effector cells upon later exposure to the same antigen.
memory cells; clones
Is this statement supported or not supported by the graph? The primary immune response takes about 28 days to reach its peak. https://session.masteringbiology.com/problemAsset/1326599/13/MB_1326599_001.jpg
not supported
s this statement supported or not supported by the graph? The primary immune response to antigen X occurred just as fast as the secondary immune response to antigen X. https://session.masteringbiology.com/problemAsset/1326599/13/MB_1326599_001.jpg
not supported
A ______________ is an agent in the environment that has the potential to cause disease.
pathogen
Which statements about B cells are true?
- When a B cell binds to a particular antigen, that cell and its daughter cells divide rapidly. - Some B cells produce antibodies, while others become memory cells. - Each B cell has a protein receptor that binds with a specific antigen. The specificity in binding between certain B cells and certain antigens is an example of structure/function correlation. Clonal selection is how the body produces a large number of the specific type of B cells needed to fight a specific threat. Antibodies fight the invader in the present whereas memory cells allow a strong immune response to the same invader in the future.
How do cells involved in the humoral response respond to antigen presentation on the surface of a B cell?
Helper T cells recognize the receptor-antigen complex and cause plasma and memory cells to be produced to then produce antibodies. Helper T cells recognize the receptor-antigen complex and activate the B cell, which divides and produces plasma and memory cells.
_________________ describes a set of defenses that is always at the ready and is the same whether a particular infectious agent has been encountered before or not.
Innate system
How do cells involved in the innate immune response detect the presence of pathogens?
Leukocytes recognize unique molecules on pathogens. Pattern-recognition receptors on leukocytes recognize and bind to unique molecules on the pathogens, such as the amino acid N-formylmethionine in bacteria. This receptor binding leads to activation of the innate immune response.
Which protein presents viral antigens on the outer surface of cells?
MHC protein MHC proteins present antigens on the surface of infected host cells (cell-mediated response) or B cells (humoral response).
________________ describes the process of engulfing and destroying a foreign particle.
Phagocytosis
Which of the following events occurs first when a wound that breaks the skin has occurred?
Platelets release proteins that form clots and decrease bleeding. The first response to broken skin is the release of clotting proteins from platelets in the bloodstream, which decreases bleeding and helps to seal the wound.
Is this statement supported or not supported by the graph? The secondary immune response is stronger than the primary immune response. https://session.masteringbiology.com/problemAsset/1326599/13/MB_1326599_001.jpg
supported
What does the y-axis of this graph represent? https://session.masteringbiology.com/problemAsset/1326599/13/MB_1326599_001.jpg
the antibody concentration in the blood
What does the blue line on this graph represent? https://session.masteringbiology.com/problemAsset/1326599/13/MB_1326599_001.jpg
the concentration of antibodies to antigen X
What does the first blue peak (around day 17) represent? https://session.masteringbiology.com/problemAsset/1326599/13/MB_1326599_001.jpg
the highest concentration of antibodies that occurs after the first exposure to antigen X
What does the second blue peak (around day 40) represent? https://session.masteringbiology.com/problemAsset/1326599/13/MB_1326599_001.jpg
the peak of the secondary immune response to antigen X
Cell-mediated immunity differs from humoral immunity in that _____.
they respond differently to invaders Humoral immunity is a function of B cells and antibody production, whereas cell-mediated immunity is a function of the activation of cytotoxic T cells.