1. high pH
2. mucus
3. tears
4. desiccation

1. Mucus secretions trap and rinse pathogens out of the body.
2. Urination carries pathogens out of the urinary tract.
3. Low pH conditions in the stomach kill some pathogens and prevent other pathogens from growing.
4. Cilia in the nasal passages and respiratory tract push mucus containing trapped pathogens out of the body.

1. macrophage
2. cytokine
3. inflammation
4. antibody

1. Inflammation is induced by molecules such as cytokines and histamine that are produced by various host cells in response to pathogens at the site of injury or infection.
2. During inflammation, all blood cells retreat from the site of infection in order to protect the circulatory system from pathogen infection.
3. Inflammation is an ongoing condition in the human body, part of the way that the innate immune system can respond immediately to an infection.
4. When an infection occurs, an immediate inflammatory response occurs as soon as pathogens enter the body.

1. macrophages
2. neutrophils
3. natural killer cells
4. cellular interferon

1. Natural killer cells are not always present in the body and must be induced, whereas macrophages are constantly present.
2. Natural killer cells actually kill foreign cells, whereas macrophages serve only a signaling function.
3. Only macrophages can invade host tissues to fight foreign cells that make their way into those tissues.
4. Natural killer cells kill foreign cells through the processes of lysis and proteolysis, whereas macrophages kill foreign cells by phagocytosis.

1. lipids
2. nucleic acids
3. carbohydrates
4. proteins

1. MHC I molecules assist with strengthening the cell membrane.
2. MHC I molecules present antigens on the surface of a cell.
3. MHC I molecules allow movement of materials across the cell membrane.
4. MHC I molecules provide signals for processes involved in cell division.

1. The complement system contains macrophages that phagocytize foreign pathogens.
2. The complement system monitors MHC I molecules on cells and destroys any cell that displays an antigen belonging to a pathogen.
3. The complement system contains a group of about 20 proteins in the blood that attack pathogens in a cascading fashion to mark and destroy them.
4. The complement system is made up of antibodies specific to each pathogen that are synthesized when a pathogen enters the body.

1. pathogen invasion
2. pathogen detection
3. pathogen reproduction
4. pathogen engulfment

1. acquired immunity
2. innate immunity
3. passive immunity
4. humoral immunity

1. A person is born having a specific immune responses against any pathogen that the body is exposed to.
2. A person is born with the ability to develop a specific immune response against any pathogen within minutes of being exposed to that pathogen.
3. A person does not have any immune response against a pathogen, but develops a temporary specific response to that pathogen that is then forgotten.
4. A person does not have specific immune response against a pathogen, but develops a specific response to that pathogen that is rapidly recalled later if infection by the same pathogen occurs again.

1. T cells
2. antibodies
3. mast cells
4. B cells

1. The adaptive immune system is faster-acting than the innate immune system.
2. The adaptive immune system produces a longer-lasting defense than the innate immune system.
3. The innate immune system produces a more specific defense than the adaptive immune system.
4. The innate immune system has a more sophisticated memory than the adaptive immune system.

1. cytotoxic T cells
2. antigen-presenting cells
3. helper T cells
4. B cells

1. The humoral immune response primarily targets infected host cells to destroy them before the infecting pathogen can reproduce.
2. The humoral immune response produces antibodies that are specifically targeted against each pathogen.
3. The humoral immune response produces cytotoxic T cells that induce apoptosis in pathogen-infected cells.
4. The humoral immune response is the only system that involves memory cells that are able to respond later to a pathogen that has invaded the body at an earlier time.

How many and what types of polypeptides make up an antibody molecule?

1. One heavy polypeptide chain and one light polypeptide chain.
2. Two heavy polypeptide chains and one light polypeptide chain.
3. Two heavy polypeptide chains and two light polypeptide chains.
4. One heavy polypeptide chain and two light polypeptide chains.

1. The antibody is showing that it has high affinity for antigens.
2. The antibody is showing that it has high avidity for antigens.
3. The antibody is showing cross-reactivity to the antigens.
4. The antibody is showing hypersensitivity to the antigens.

1. The antibodies were synthesized in response to infections by different pathogens.
2. The antibodies were transmitted as the result of passive immunity.
3. The antibodies have different specificities of antigen binding.
4. The antibodies belong to different classes of immunoglobulin molecules.

1. DNA polymerase
2. DNA recombinase
3. DNA ligase
4. DNA helicase

1. RNA processing → DNA rearrangement → transcription → translation → mature antibody
2. Transcription → RNA processing → DNA rearrangement → translation → mature antibody
3. DNA rearrangement → RNA processing → transcription → translation → mature antibody
4. DNA rearrangement → transcription → RNA processing → translation → mature antibody

1. maladaptive immune responses to otherwise harmless proteins
2. measure of the attraction between an antigen and an antibody
3. total binding strength of a multivalent antibody with an antigen
4. binding of an antibody to an antigen different from the one that elicited its synthesis

1. An allergic response occurs when B cells produce IgE molecules in response to a foreign protein, which causes histamine to be released.
2. An allergy results from an immune response to an antigen that does not cause harm and that the body needs no defense against.
3. People with allergies develop unpleasant symptoms such as watery, itchy eyes, swollen tissues, and sneezing.
4. When their blood is tested, people with allergies show that they have antibodies that bind to one or more foreign proteins.

1. cross reactive
2. epitopes
3. allergens
4. autoantibodies

1. Their B cells produced IgE molecules in response to a harmless protein, which caused histamine to be released.
2. Their B cells responded to a self protein to produce autoantibodies, which elicited inflammation that caused organ damage.
3. They had a delayed response to a harmful protein that entered the body and activated both the innate and adaptive immune systems.
4. They acquired antibodies to insulin through passive immunity, and these antibodies bind to insulin whenever it is produced in the body.

1. innate, acquired, and immunodeficiency
2. variable, constant, and recombinant
3. immediate, delayed, and autoimmunity
4. active, passive, and adaptive

1. binding of an antibody to a viral antigen
2. immune response to self antigens
3. maladaptive immune response to harmless foreign proteins
4. failure to mount an immune response