AQA GCSE Biology Foundation (8461), Foundation tier · Infection and response › Communicable diseases
Practise Discovery and development of drugs. 7 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
Where medicines come from (plants, microorganisms and chemists' laboratories) and how a new drug is tested before it can be used: preclinical testing, clinical trials, placebos, double blind trials and peer review. A common 4 to 6 mark 'describe' question, and a good source of data questions.
Key facts
Digitalis (heart drug) ← foxgloves
Aspirin (painkiller) ← willow
Penicillin ← Penicillium mould, discovered by Alexander Fleming
New drugs are tested for toxicity, efficacy and dose
Preclinical testing: cells, tissues and live animals
Clinical trials: healthy volunteers and patients; very low doses first, then find the optimum dose
Placebo = looks like the drug but contains no drug
Double blind: neither doctors nor patients know who gets the drug or the placebo
Peer review: other experts check the results before they are published
Notes
Where drugs come from
Traditionally, drugs were extracted from plants and microorganisms.
The heart drug digitalis comes from foxgloves. The painkiller aspirin comes from willow.
Penicillin was discovered by Alexander Fleming from the Penicillium mould. He noticed that bacteria did not grow around some mould that had got onto one of his culture plates.
Most new drugs are now synthesised by chemists in the pharmaceutical industry, but the starting point may still be a chemical extracted from a plant.
Testing a new drug
diagram
New drugs must be tested and trialled to check that they are safe and effective. They are tested for toxicity (harm), efficacy (how well they work) and dose.
Preclinical testing is done in a laboratory using cells, tissues and live animals. Animals show the effect of the drug on a whole body.
The stages of testing a new drug, in order.
Clinical trials use healthy volunteers and patients.
Very low doses are given at the start of a clinical trial, to check that the drug is safe.
If the drug is safe, further clinical trials find the optimum dose: the dose that works best with the fewest side effects.
Placebos and double blind trials
A placebo looks like the drug but does not contain the drug. In a trial, some patients get the drug and some get the placebo.
Some patients feel better just because they believe they are being treated, so comparing the two groups shows whether the drug has a real effect.
In a double blind trial, neither the doctors nor the patients know who has received the drug and who has received the placebo until the trial is complete. This stops their expectations affecting the results.
Publishing the results
The results are published only after peer review: other scientists who are experts in the same field check the method, results and conclusions.
This makes it less likely that false or biased claims are published.
How to answer each type of question
Recall: sources of drugs
1 mark eachGrade 3
Learn the three pairs: foxglove → digitalis, willow → aspirin, Penicillium → penicillin.
Remember who discovered penicillin: Alexander Fleming.
Example. Give the original source of each drug. (a) Aspirin (b) Digitalis (c) Penicillin
In data questions, compare the drug group with the placebo group, and use percentages if the groups are different sizes.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
Match drugs to their original sourcesDigitalis from foxgloves, aspirin from willow, and penicillin from Penicillium mould (discovered by Alexander Fleming).
Grade 4
State what new drugs are tested forToxicity (is it harmful?), efficacy (does it work?) and dose (how much should be given?).
Grade 5
Describe preclinical testingThe drug is tested in a laboratory on cells, tissues and live animals before any people take it.
Grade 5
Describe the stages of clinical trialsVery low doses are given first to check safety; further trials on patients find the optimum dose.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Many drugs were first extracted from living organisms. The painkiller aspirin originates from which plant?
Willow
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Many drugs were first extracted from living organisms.
(a) Which drug originates from foxgloves? Tick (✓) one box.[1]
Aspirin
Digitalis
Paracetamol
Penicillin
(b) The painkiller aspirin originates from which plant?[1]
(c) Which scientist discovered penicillin?[1]
(d) Penicillin was discovered in a type of mould. What type of organism is a mould?[1]
(e) Most new drugs are now made by chemists in the pharmaceutical industry. Suggest why scientists still study chemicals from plants.[1]
Show the answer and mark scheme
(a)Answer: Digitalis
(b)Answer: Willow
willow
(c)Answer: Alexander Fleming
(Alexander) Fleming
(d)Answer: Fungus
fungus
(e)
the starting point for a new drug may be a chemical extracted from a plant / plants may contain chemicals that could be useful drugs
Question 2Medium7 marks
New drugs are tested before they can be used to treat patients.
(a) New drugs are tested for toxicity, efficacy and dose. Explain what is meant by each of these terms.[3]
(b) Preclinical testing is done in a laboratory. Give two things that drugs are tested on during preclinical testing.[2]
(c) The first clinical trials use healthy volunteers who are given very low doses of the drug. Explain why very low doses are used.[2]
Show the answer and mark scheme
(a)
toxicity: whether the drug is harmful / has harmful side effects
efficacy: whether the drug works / how well it works
dose: how much of the drug should be given (and how often)
(b)
cells
tissues
live animals
(c)
to check that the drug is safe / has no harmful side effects (in humans)
a low dose reduces the risk of harm if the drug turns out to be toxic