4_ Acquired specific Immunity_ Immune Response

Which statement best defines an antigen in the context of immunity?

• A substance that triggers a specific immune response

• A protein that always originates from human tissues

• A general barrier that blocks all pathogens equally

• A white blood cell that engulfs cellular debris

Which cell type primarily produces antibodies that match specific antigens?

• Platelets

• Erythrocytes

• Macrophages

• Lymphocytes

Which scenario best illustrates self versus non‑self discrimination by acquired immunity?

• Neurons releasing signals that coordinate muscle movement

• Stomach acid lowering pH to kill many invaders

• Skin secreting oils to slow growth of all microbes

• Lymphocytes attacking foreign viral proteins but not body proteins

Why is each lymphocyte considered highly specific in its antigen recognition?

• It carries receptors that bind only one antigen

• It secretes enzymes that digest many antigens

• It migrates to every tissue during infection

• It divides only once after activation

A person is infected by the same pathogen months after recovery but shows almost no symptoms. Which acquired immunity function explains this outcome?

• Physical barriers preventing pathogen entry at skin

• General inflammation increasing blood vessel permeability

• Immunological memory recognizing the antigen rapidly

• Complement proteins lysing bacteria nonspecifically

Which statement best describes the humoral immune response?

• B cells secrete antibodies targeting free antigens

• Natural killer cells trigger inflammation in nearby tissues

• Macrophages engulf any pathogen without specificity

• T cells destroy cells already infected by pathogens

Which cell type is primarily responsible for the cell-mediated immune response?

• Basophils releasing histamine in allergic reactions

• Neutrophils performing non-specific phagocytosis

• T lymphocytes recognizing infected cells

• B lymphocytes releasing soluble antibodies

In acquired immunity, what is the role of antibodies produced by B cells?

• Trigger fever by acting on the hypothalamus

• Lyse infected host cells through perforin release

• Convert antigens into memory cells directly

• Bind specific antigens to neutralize or tag them

A virus has already entered and replicated inside some body cells. Which immune pathway is most directly involved next?

• Complement-only pathway without lymphocytes

• Innate barriers like skin and mucous membranes

• Cell-mediated response using cytotoxic T cells

• Humoral response producing circulating antibodies

Which sequence best summarizes how acquired immunity develops after antigen exposure?

• Antigen digestion, glucose release, ATP synthesis, apoptosis in neutrophils

• Skin barrier activation, mucus secretion, cilia movement, cough reflex

• Nonspecific inflammation, fever induction, scar formation, tissue remodeling

• Antigen recognition, clonal expansion, antibody production, memory formation