These eight original questions follow the four lessons in immunity. The bacterium and the figures are invented.
Try each question before opening the answer, and write full sentences for the explain questions.
Questions
Q1. Sort into non-specific or specific: stomach acid, antibodies, phagocytes.
Answer
Stomach acid and phagocytes are non-specific, since they act against many kinds of germ. Antibodies are specific, since each fits one antigen.
Q2. A student writes: “Phagocytes are specific because they are white blood cells.” Correct it.
Answer
Phagocytes are non-specific, because they engulf many kinds of pathogen. Being a white blood cell does not make a defence specific.
Q3. State what an antigen is and what an antibody is.
Answer
An antigen is a marker on the surface of a pathogen. An antibody is a protein made by the body that fits one antigen and binds to it.
Q4. Explain how the body responds when Type X bacteria enter a cut.
Answer
Type X carries an antigen. A lymphocyte with a matching receptor recognises it and multiplies, and the new cells make antibodies that fit the antigen. The antibodies bind to Type X, phagocytes engulf it, and memory cells remain.
Q5. Why does a second infection by Type X cause a faster response?
Answer
Memory cells from the first infection recognise the antigen quickly and multiply fast. More antibodies are made sooner and in larger amounts.
Q6. A vaccine introduces an antigen. Is the immunity active or passive? Give a reason.
Answer
Active. The person’s own lymphocytes make the antibodies and memory cells after meeting the antigen.
Q7. Compare active and passive immunity on memory cells and duration.
Answer
Active immunity forms memory cells and lasts long, whereas passive immunity forms none and is short-lived because the received antibodies are used up.
Q8. Invented data: first response peak is 30 units on Day 12; second response peak is 120 units on Day 38 after a second exposure on Day 30. Compare the two peaks and explain.
Answer
The second peak (120 units) is four times the first (30 units), and it occurred 8 days after the second exposure, compared with 12 days after the first. Memory cells made the second response faster and larger.
If you got these wrong
Q1 and Q2 point to non-specific versus specific defence. Q3 to Q5 need explaining antigen-antibody responses.
Q6 and Q7 link to comparing active and passive immunity. Q8 belongs to reading immune-response graphs.
The biological data interpretation trainer and the mistake log help you repeat and track errors. For teacher support, see online one-to-one Biology tuition.