They expose your immune system to a harmless form of the pathogen so memory cells form, allowing rapid response if exposed later. Learn it step by step →
Infection & Response is a core part of GCSE Biology. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
Binary fissionBacterial reproduction by splitting in two
Doubling timeTime for a bacterial population to double
VaccineDead or weak pathogen that triggers immunity
Memory cellLymphocyte that remembers a past pathogen
AntibioticDrug that kills bacteria (not viruses)
ResistanceBacterial mutation that survives an antibiotic
Monoclonal antibodyIdentical antibodies from one type of B cell
HybridomaB cell fused with tumour cell — divides forever
hCGPregnancy hormone detected in urine tests
CuticleWaxy plant layer that blocks pathogens
DigitalisHeart drug originally from foxglove plants
PenicillinFirst antibiotic, from Penicillium mould
PathogenA microorganism that causes disease
BacteriaLiving cells that release toxins (e.g. Salmonella)
What your exam board covers
Where Infection & Response sits in each exam board's specification. Tap a board to see what it lists.
Questions where students often pick the tempting wrong answer — make sure you know the right one:
How do vaccines protect you from a disease?✗ Vaccines kill the pathogen if it ever enters the body.✓ They expose your immune system to a harmless form of the pathogen so memory cells form, allowing rapid response if exposed later.
Why don't antibiotics work on viruses?✗ Viruses are too big✓ Antibiotics target structures and processes found only in bacteria (such as the cell wall), which viruses do not have; viruses reproduce inside your own cells.
What does a vaccine contain?✗ A live, full-strength pathogen✓ A dead or weakened pathogen
What is a hybridoma made by fusing?✗ Two B lymphocytes✓ A B cell and a tumour cell
Can antibiotics cure a cold or the flu?✗ Antibiotics cure viral illnesses like colds and flu.✓ No — colds and flu are caused by viruses, and antibiotics only kill bacteria.
Practise Infection & Response — free games
Test yourself with these quick revision games for this topic:
