6.5.1 Types of immunity and pathogen evasion in the evolutionary race Quiz: Pearson Edexcel Biology A (Salters-Nuffield), Unit 6

The 20 questions

1. Which type of immunity is acquired by receiving antibodies from a mother across the placenta or in breast milk?

   • Artificial active immunity, since the infant is given a vaccine that stimulates memory cells
   • Natural passive immunity, since antibodies are transferred without the infant making them
   • Natural active immunity, since the infant produces its own antibodies after an infection
   • Artificial passive immunity, since the infant is injected with antibodies made in another animal

2. Vaccination provides which type of immunity?

   • Artificial passive immunity, since the person is given ready-made antibodies by injection
   • Natural active immunity, since the person catches the disease and recovers from it
   • Artificial active immunity
   • Natural passive immunity, since antibodies pass from the mother to the infant in breast milk

3. An injection of antivenom to treat a snake bite provides which type of immunity?

   • Natural passive immunity, since antibodies are transferred to the patient through the placenta
   • Artificial active immunity, since the antivenom stimulates the patient's memory cells to divide
   • Artificial passive immunity, since antibodies made in another animal are given to the patient
   • Natural active immunity, since the patient's own lymphocytes produce antibodies after the bite

4. Which pathogen evasion strategy involves the pathogen repeatedly changing its surface antigens?

   • Hiding inside host cells, in which the pathogen avoids circulating antibodies and phagocytes
   • Antigenic variation, which allows the pathogen to escape recognition by antibodies made against earlier forms
   • Latency, in which the pathogen remains dormant inside host cells without being replicated
   • Producing a thick capsule, which prevents phagocytes from binding to the pathogen surface

5. Herpes viruses can remain in the body for many years, periodically reactivating. Which evasion strategy does this illustrate?

   • Latency, in which the virus persists dormant and avoids being cleared by the immune response
   • Production of a thick capsule that stops phagocytes from engulfing the virus particles
   • Antigenic variation, in which the virus changes its surface proteins at every infection
   • Inhibition of the complement system, which stops antibodies from tagging the virus

6. The theory of an evolutionary race between pathogens and hosts is supported by:

   • Pathogens that always become less virulent over time, so host defences are never challenged
   • Pathogens that remain identical for thousands of years, so the host never needs to change its defences
   • Hosts that stop evolving once they acquire a vaccine, so the pathogen loses its advantage completely
   • Pathogens that evolve evasion mechanisms, such as changing antigens

7. Which type of immunity is provided by a vaccine containing inactivated pathogens?

   • Natural passive immunity, since the inactivated pathogens cross the placenta to the foetus
   • Natural active immunity, since the infection is caught and the immune system is activated by it
   • Artificial active immunity
   • Artificial passive immunity, since the inactivated pathogens are antibodies given by injection

8. Which feature helps some bacteria, such as pneumococci, evade phagocytosis?

   • A thick polysaccharide capsule that makes it harder for phagocytes to bind and engulf the bacterium
   • A flagellum that rotates so fast that phagocytes cannot approach the cell surface at all
   • A thin peptidoglycan wall that dissolves rapidly in the presence of host lysozyme
   • A nucleus that holds the genetic material and prevents phagocytes from entering the cell

9. Why might a person who has had natural active immunity to a disease still be vulnerable to a new strain of the same pathogen?

   • Antibodies from the first infection become toxic when they encounter the same pathogen again
   • Natural immunity lasts only a few hours, so the body always forgets the pathogen after that
   • The pathogen's antigens have changed
   • The immune system deliberately destroys its own memory cells after each infection to avoid overreaction

10. Which of these is an example of natural passive immunity?

    • Antibodies given to a patient by injection of immunoglobulin from donated blood
    • Antibodies transferred from mother to foetus across the placenta
    • Antibodies produced after a person recovers from a bout of measles
    • Antibodies produced after a person receives a tetanus vaccine in the arm

11. Which statement about immunological memory is correct?

    • It is produced by plasma cells that release antibodies continuously after the first infection ends
    • It is produced by red blood cells that carry antigen fragments to the lymph nodes for many years
    • It is produced by neutrophils that remember the shape of pathogens and destroy them on re-exposure
    • It is produced by memory B and T cells that respond faster to a repeated exposure to the same antigen

12. Which evasion strategy is used by viruses that inhibit the complement system or interferon responses?

    • Interference with innate defences
    • Production of a capsule, which allows the virus to digest the complement proteins
    • Antigenic variation, which changes the shape of the antibodies made by the host to fit the virus
    • Latency, in which the virus is destroyed by complement as soon as it enters the host

13. A researcher compares two vaccines, one giving artificial active immunity and one giving artificial passive immunity. Which difference is correct?

    • Active immunity and passive immunity produce identical memory cells, so both last for a lifetime
    • Active immunity develops over days to weeks and lasts long term, while passive immunity acts at once but briefly
    • Active immunity uses antibodies from another species, while passive immunity uses the patient's own memory cells
    • Active immunity is immediate but lasts only one hour, while passive immunity lasts many years

14. Which statement evaluates the use of antibiotics as a counter to pathogen evasion?

    • Antibiotics always eliminate all evolutionary changes in pathogens because they target every mutation
    • Antibiotics are irrelevant to the evolutionary race because bacteria never change their antigens or their genes
    • Antibiotics can help but do not stop evolutionary change, since resistant pathogen populations may still emerge
    • Antibiotics make pathogens more evasive, because they always cause the pathogen to hide inside host cells

15. Why does latency make some infections harder to control?

    • Because latent pathogens are always destroyed by phagocytes before they can be detected
    • Because latent pathogens are visible to all immune cells, so the immune system overreacts
    • Because latency increases the number of antibodies, which then block the body's own cells
    • Because the pathogen is hidden from many immune responses and may reactivate later

16. Which type of immunity would be given to a person who is exposed to rabies and then receives both immunoglobulin and a vaccine?

    • Only natural active immunity, since the person's own immune system is responding to the virus
    • Neither type, since immunoglobulin and vaccines both act only on memory cells in the bone marrow
    • Only natural passive immunity, since the person's mother transferred antibodies during pregnancy
    • Both artificial passive immunity from the immunoglobulin and artificial active immunity from the vaccine

17. Which statement about the evolutionary race is best supported by evidence?

    • Pathogens evolve, but hosts never do, so the outcome is always decided by the pathogen alone
    • Hosts and pathogens evolve independently, so there is never any selection pressure on either side
    • Hosts evolve, but pathogens remain identical, so no evasion mechanism has ever been selected for
    • Host and pathogen populations exert reciprocal selection pressure

18. A pathogen that produces a protein which binds and inactivates host antibodies is best described as:

    • Using antigenic variation to change its surface markers at each cell division
    • Using an evasion strategy that blocks the host's specific immune response
    • Using a capsule to prevent phagocytosis, but not interfering with antibodies at all
    • Using latency to remain inside host macrophages without being detected by any immune cells

19. Which is an example of a pathogen that uses latency to persist in the body?

    • Salmonella bacteria, which are destroyed completely by stomach acid in every infected person
    • Varicella-zoster virus, which stays dormant in nerve tissue after chickenpox and can reactivate later
    • Influenza virus, which replicates rapidly in the airways and is usually cleared within about one week
    • Staphylococcus aureus, which forms spores that cannot be detected by antibodies in the blood

20. Which statement about natural active immunity is accurate?

    • It is acquired after infection, when the body makes its own antibodies and memory cells
    • It is acquired from injected antibodies that the body does not make itself at any stage
    • It is acquired from vaccine antigens delivered by injection, which the body recognises as foreign
    • It is acquired from maternal antibodies in breast milk, which the infant receives after birth

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