Your immune system learns its enemy

Science · The Human Body · ages 16-17

Name ______________________ Date ____________

Which cells release antibodies into body fluids?
- Cytotoxic T cells
- Phagocytes
- B cells
What does it mean to say the adaptive response is specific?
- It targets one exact antigen shape
- It attacks every invader the same way
- It leaves no memory cells behind
The secondary immune response is faster and stronger than the primary response.
Circle one: True False
A virus is hiding inside your own throat cells. Which arm of the response deals with this?
- The cell-mediated arm, led by T cells
- The humoral arm, led by B cells
- Antigen presentation by plasma cells
A phagocyte has just swallowed a flu virus. What must happen next to switch on the tailored response?
- It releases antibodies into the blood itself
- It shows antigen pieces on its surface for helper T cells
- It divides into memory cells on the spot
Why does the primary response take days to get going?
- Memory cells slow down the first meeting
- The matching B and T cells must be found and copied first
- Helper T cells wait for antibodies to arrive
Sam says tolerance means the immune system holds back against vaccines. What is wrong with this?
- Tolerance means the system forgets every antigen
- Tolerance means antibodies stop working
- Tolerance is about leaving your own healthy cells alone
A vaccine protects you without making you sick. How?
- It fills your blood with antibodies that last forever
- It leaves memory cells behind without a real infection
- It teaches phagocytes to skip antigen presentation

Answer key

For grown-ups. Fold this page away before handing over the rest.

B cells · B cells become plasma cells that release antibodies to patrol blood and fluids.
It targets one exact antigen shape · Specificity means the response is aimed at one exact antigen shape, not at invaders in general.
True · Memory cells from the first meeting attack at once, so the second fight goes quicker.
The cell-mediated arm, led by T cells · Infected body cells are handled by T cells in the cell-mediated arm, while antibodies patrol fluids.
It shows antigen pieces on its surface for helper T cells · Showing antigen pieces to helper T cells is the hand-off that switches the tailored response on.
The matching B and T cells must be found and copied first · Only the few cells whose receptors match are chosen, and building that army takes days.
Tolerance is about leaving your own healthy cells alone · Tolerance is the system leaving your own healthy cells alone. Vaccines work by building memory, not by being spared.
It leaves memory cells behind without a real infection · Meeting the antigen through a vaccine leaves waiting memory cells, so the real pathogen meets a fast secondary response.