Compare types of immunity
Distinguish active and passive immunity, and natural and artificial acquisition.
AS Level · Cambridge International Biology 9700, 2028–2030. Written practice is self-checked; human subject-teacher review and supervised practical evidence remain separate.
Before you begin
- Pathogens carry antigens, and specific receptors on lymphocytes can recognise complementary antigen shapes.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which type of immunity involves receiving ready-made antibodies?
What you will learn
- Compare active and passive immunity by antibody source and memory
- Classify natural and artificial routes of immunity
Build the explanation
Active immunity develops when a person's immune system responds to an antigen and forms memory cells; it may follow infection naturally or vaccination artificially. Passive immunity occurs when ready-made antibodies are received from another source; it can be natural, such as antibodies passed from mother to baby through placenta or breast milk, or artificial, such as an antibody preparation given by injection. Passive immunity can provide immediate antibodies but does not create the recipient's memory cells.
Apply it carefully
Classify each case along two separate axes. Active/passive asks whether the person's own immune response made the antibodies; natural/artificial asks how the immunity was acquired. Active responses take time but form memory; passive protection is immediate but temporary as received antibodies are broken down. Avoid describing natural passive immunity as inherited genes or artificial active immunity as ready-made antibodies.
Pause and explain
Which type forms memory cells in the recipient?
Worked example
A vaccine stimulates a person's own lymphocytes to produce antibodies and memory cells. Classify the immunity.
Show the worked solution
- The person's own response is active.
- Vaccination is an artificial route.
Answer Artificial active immunity.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Classify antibodies transferred from a mother across the placenta using both active/passive and natural/artificial terms.
Give me a hint
The baby's immune system receives antibodies made by another person.
Compare my reasoning
- The baby receives ready-made antibodies, so immunity is passive.
- Transfer through the placenta is a natural route.
This is natural passive immunity: the baby receives antibodies made by the mother rather than producing them through its own active response.
Look for these in your work
- Passive correctly identified
- Natural route correctly identified
Compare active immunity after vaccination with passive antibody transfer in terms of speed and memory.
Give me a hint
Consider whether antibodies are received or made by the recipient.
Compare my reasoning
- Vaccination stimulates an active response that takes time and forms memory.
- Passive transfer supplies antibodies immediately but does not form recipient memory cells.
Vaccination produces artificial active immunity: the recipient's response takes time but forms memory cells. Passive antibody transfer is immediate but does not form the recipient's memory cells and is temporary as antibodies are broken down.
Look for these in your work
- Active response and memory stated
- Passive speed and no-memory stated
A person receives an injected antibody preparation. Explain why this is not artificial active immunity.
Give me a hint
Classify by who made the antibodies.
Compare my reasoning
- The antibodies are already made and are received by the person.
- That is artificial passive immunity; it does not rely on the person's own antibody production.
The person receives ready-made antibodies by an artificial route, so this is artificial passive immunity. Artificial active immunity would require an antigen to stimulate the person's own immune response and memory formation.
Look for these in your work
- Artificial route named
- Passive classification justified
- Active contrast explained
Common mistakes
- Treating passive immunity as memory-cell formation
- Confusing artificial passive injection with vaccination
- Using natural/artificial as synonyms for active/passive
What can you explain now?
Which type of immunity involves receiving ready-made antibodies?
Compare with the explanation
Passive immunity
The recipient does not make those antibodies as part of this protection.
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Make it stick
Who makes the antibodies in active and passive immunity, and how do natural and artificial routes differ?
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