NESA Biology Immunity

Complement proteins circulate in the blood in an inactive state and must be triggered by specific pathways (such as the presence of pathogens or antibodies) to become activated.

The complement system is primarily part of the innate immune system and is activated by antibodies or pathogen surfaces, not by helper T cells.

While some complement byproducts can trigger histamine release to promote inflammation, complement proteins are endogenous immune components, not foreign allergens.

Antigens are typically foreign substances (like viral or bacterial proteins) that trigger an immune response, rather than a defensive component produced by the body.

Antibodies are the primary component of humoral immunity, not cell-mediated immunity, and are produced by B cells to target extracellular pathogens.

Memory B cells are part of the humoral immune response, which relies on the production of antibodies rather than direct cell-to-cell combat.

While eosinophils are involved in allergic reactions and parasitic infections, they primarily release toxic granule proteins and other inflammatory mediators rather than being the main source of histamine.

Macrophages are phagocytic cells responsible for engulfing and digesting pathogens and cellular debris; they do not release histamine.

Natural killer cells are cytotoxic lymphocytes that identify and destroy virus-infected or cancerous cells, not cells that release histamine during an allergic response.

Incorrect. Natural killer cells destroy infected or cancerous host cells by inducing apoptosis, whereas phagocytes like macrophages and neutrophils are responsible for engulfing pathogens.

Incorrect. During an inflammatory response, the body typically increases the production and circulation of white blood cells to combat the infection.

Incorrect. Inflammation is actually a key mechanism of activating the innate immune system to protect the body, rather than preventing its activation.

Statements I (matured in bone marrow) and II (produces antibodies) describe B lymphocytes, not T lymphocytes.

Statement II (produces antibodies) is a characteristic of B lymphocytes, which differentiate into antibody-producing plasma cells.

Statement I (matured in bone marrow) applies to B lymphocytes, whereas T lymphocytes mature in the thymus gland.

B cells produce antibodies to neutralize pathogens rather than directly attacking infected cells; direct destruction of virally infected cells is the function of cytotoxic T cells.

Diffusing across a synaptic gap is the specific function of neurotransmitters in the nervous system, not cytokines.

Rapid communication with distant cells is characteristic of the nervous and endocrine systems. Cytokines typically act locally and more slowly via autocrine or paracrine signaling.

Mast cells reside in connective tissues and mucous membranes, so they are already present at infection sites rather than being transported there by the lymphatic system.

Platelets circulate in the blood and are part of the cardiovascular system's clotting cascade, not the lymphatic system.

Injected monoclonal antibodies are primarily distributed throughout the body via the bloodstream, not the lymphatic system.

The digestive and reproductive tracts often rely on acidic secretions, such as stomach acid and vaginal fluids, rather than alkaline secretions to inhibit microbial growth.

Cerumen is earwax, which is specifically produced to protect the ear canal, not the digestive, urinary, or reproductive tracts.

While cilia are present in parts of the reproductive tract, they are primarily the main defense mechanism for the respiratory tract, not all three of these systems.

T and B cells are part of the adaptive immune response, which takes days to activate during a first exposure; rapid initial responses are characteristic of the innate immune system.

Physical barriers, such as the skin and mucous membranes, are part of the innate immune system, whereas T and B cells are specialized white blood cells circulating in the body.

While B cells can bind directly to intact antigens on pathogens, T cells can only recognize fragmented antigens presented by Major Histocompatibility Complex (MHC) molecules on other cells.

Destroying infected cells is primarily the role of cytotoxic T cells, and phagocytosis is performed by cells like macrophages and neutrophils, not plasma cells.

While many immune cells release cytokines, secreting them to coordinate the immune response is the primary function of helper T cells.

Antigen presentation to helper T cells is performed by professional antigen-presenting cells like dendritic cells, macrophages, and naive B cells, rather than fully differentiated plasma cells.

IgE antibodies are involved in allergic reactions by binding to mast cells and basophils to trigger histamine release, but they do not present antigens to T cells.

Complement proteins are part of the innate immune system that help destroy pathogens and promote inflammation, but they are not involved in antigen presentation to T cells.

While dendritic cells are antigen-presenting cells that use various receptors to uptake allergens, the actual presentation of the processed allergen to T cells is not done by these uptake receptors.

While complement proteins and histamine are elevated during inflammation, heparin and tissue fluid levels would also be high, not low.

Inflammation triggers the release of complement proteins, histamine, and heparin to fight infection and increase blood flow, so these would all be high, not low.

Complement proteins are actively recruited during inflammation, and tissue fluid increases due to vascular permeability (causing swelling), so both would be high.