AP Biology: Immune System Practice Questions
Test yourself on AP Biology: Immune System with 12 original AP Exams practice questions. Pick an answer to see instant feedback and a full explanation.
Free original practice questions for study purposes. Open Exam Prep is an independent study resource and is not affiliated with, endorsed by, or sponsored by the makers of AP Exams.
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1. Which feature is part of the innate immune response rather than the adaptive immune response?
Explanation. Innate immunity includes nonspecific defenses such as skin, mucous membranes, inflammation, phagocytes, and complement proteins. Adaptive immunity uses antigen-specific lymphocytes and can generate immunological memory.
2. A macrophage engulfs a bacterium and displays fragments of bacterial proteins on its surface. What is the main purpose of this antigen presentation?
Explanation. Antigen-presenting cells display peptide fragments on major histocompatibility complex molecules. Helper T cells with matching receptors can recognize the antigen and coordinate adaptive immune responses.
3. What best explains why a secondary immune response is often faster and stronger than a primary response to the same antigen?
Explanation. After an initial adaptive response, some B and T cells become memory cells. On later exposure to the same antigen, these cells can activate more quickly and produce a stronger response.
4. Which statement best describes clonal selection in adaptive immunity?
Explanation. Clonal selection means that antigen binding selects lymphocytes with matching receptors. Those activated cells proliferate into clones that can become effector cells and memory cells.
5. A mutation prevents a person from producing functional helper T cells. Which outcome would be most likely?
Explanation. Helper T cells release signals that activate B cells, cytotoxic T cells, and other immune cells. Without functional helper T cells, several adaptive immune pathways are poorly coordinated.
6. Which immune cell type directly kills body cells that are infected with viruses or otherwise display abnormal antigen patterns?
Explanation. Cytotoxic T cells recognize antigen fragments presented by infected or abnormal host cells and can trigger cell death. Plasma cells secrete antibodies, while red blood cells and platelets are not lymphocyte effectors.
7. Why do antibodies help remove extracellular pathogens?
Explanation. Antibodies bind specific antigens. This binding can neutralize toxins or viruses, block pathogen attachment, promote phagocytosis, and help activate complement pathways.
8. A vaccine contains a harmless antigen from a pathogen. Which result is the main goal of vaccination?
Explanation. Vaccines expose the immune system to antigen in a controlled way so adaptive immunity can form memory cells. Later exposure to the pathogen can then trigger a faster protective response.
9. Which example best illustrates an autoimmune response?
Explanation. Autoimmunity occurs when immune recognition fails to distinguish self from nonself and immune cells attack the body's own tissues. The other examples describe normal defense mechanisms.
10. During inflammation, small blood vessels near damaged tissue become more permeable. What is a likely benefit of this change?
Explanation. Inflammation increases blood flow and vessel permeability near injured or infected tissue. This helps immune cells, signaling molecules, and defensive proteins reach the site more effectively.
11. Which molecule class is most directly responsible for allowing T cells to recognize antigen fragments displayed by host cells?
Explanation. Major histocompatibility complex proteins present peptide fragments on cell surfaces. T cell receptors recognize antigens in the context of these MHC molecules.
12. A student compares B cells and T cells. Which statement is most accurate?
Explanation. B cells can become plasma cells that secrete antibodies, and T cells include helper cells that coordinate responses and cytotoxic cells that kill infected or abnormal cells. Both cell types contain DNA and are part of adaptive immunity.
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FAQ
What immune system ideas should I know for AP Biology?
Focus on innate versus adaptive immunity, antigen presentation, B cells, helper and cytotoxic T cells, antibodies, clonal selection, memory cells, vaccination, inflammation, and self versus nonself recognition.
How can I distinguish innate and adaptive immunity on practice questions?
Innate immunity is fast and nonspecific, including barriers, inflammation, phagocytes, and complement. Adaptive immunity is antigen-specific, uses B and T lymphocytes, and can produce memory after exposure.
What mistakes should I avoid on AP Biology immune system questions?
Do not treat antibodies and T cell receptors as interchangeable. Antibodies bind antigens outside cells, while T cells typically recognize antigen fragments presented on host-cell surface proteins.