Infection & Response
What's covered
Key facts
Antibiotics do not work against influenza or any other viral illness.
Antibiotics kill bacteria or stop them reproducing by damaging cell walls, membranes, or protein synthesis.
Human clinical trials run in phases: Phase 1 uses a small group of healthy volunteers (safety, low dose, side effects); Phase 2 uses patients with the disease (efficacy and dose); Phase 3 uses a large patient group (effectiveness vs existing treatment / placebo).
Antibodies are proteins that bind to specific antigens on a pathogen, marking it for destruction.
A hybridoma cell (lymphocyte + tumour cell) divides indefinitely and produces a specific antibody.
Gonorrhoea is a bacterial sexually transmitted infection that can cause infertility if untreated.
Patients must finish the full course of antibiotics; stopping early leaves resistant bacteria alive to reproduce.
Antibiotics do not treat viral infections because they target bacterial cell structures (cell wall, ribosome, DNA gyrase) that viruses lack.
Clinical trials are the stage at which a drug is first tested on people, after passing preclinical safety screens.
White blood cells also produce antitoxins, which neutralise the toxins released by some pathogens.
Sample questions
A taste of the 82 questions in this topic — answers marked. Sign up to practise the full set with spaced repetition.
Why must patients finish a full course of antibiotics?
- •Antibiotics work better when finished
- •It's required by UK law to finish
- •Patients feel better quickly when finished
- ✓Stopping early leaves resistant bacteria alive
What are the four pathogen types? Give a disease example of each.
- •Bacteria (athlete's foot), viruses (Salmonella), fungi (malaria), protists (rose black spot).
- •Bacteria (flu), viruses (rose black spot), fungi (HIV), protists (Salmonella).
- •Bacteria (measles), viruses (cholera), fungi (malaria), protists (TB).
- ✓Bacteria (TB), viruses (flu), fungi (athlete's foot), protists (malaria).
In which stage are drugs tested for the first time on people?
- ✓Clinical trials
- •Manufacturing
- •Marketing
- •Preclinical (cells)
Which non-specific defence is the skin?
- •Killing all bacteria with heat
- ✓Physical barrier preventing pathogen entry
- •Producing white blood cells inside
- •Triggering antibodies on contact
What cell is made when a lymphocyte fuses with a tumour cell?
- ✓A hybridoma — it divides indefinitely and produces specific antibodies.
- •A memory cell — it stays dormant until antigen re-exposure occurs.
- •A phagocyte — it engulfs pathogens but does not make antibodies.
- •A plasma cell — it secretes antibodies but cannot keep dividing.
Which pathogen causes malaria, including its mode of spread?
- •A bacterium spread via contaminated drinking water in poor sanitation.
- •A fungus spread by airborne spores inhaled in tropical climates.
- ✓A protist (Plasmodium) spread by infected Anopheles mosquitoes.
- •A virus spread by direct contact with infected blood or fluids.
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