Explain why new medicines must be tested before they can be given to patients.

WJEC GCSE Biology (Wales) — 2.6.3 Medicines and drugs · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

1. To confirm the medicine is effective against the target disease or pathogen.
2. To ensure the medicine is safe and does not cause harmful side effects.
3. Initial tests are carried out on cells, tissues or animals before any human use.
4. Clinical trials on human volunteers are then conducted to determine the correct dose and to confirm safety and effectiveness in people.

Examiner tips

Use the exact wording from the mark scheme (effective, safe, cells/tissues/animals, clinical trials).
Show the logical sequence: effectiveness → safety → pre‑clinical → clinical.
Keep each point short and to the point, matching the four marks.

Common mistakes

Writing vague reasons such as ‘to make it better’ instead of ‘effective’.
Omitting the pre‑clinical testing on cells/tissues/animals.
Confusing the order of testing (clinical trials before pre‑clinical).

Mark scheme (4 marks)

New medicines must be tested to check they are effective / that they work against the disease or pathogen
New medicines must be tested to check they are safe / do not cause harmful side effects
New medicines are first tested on cells / tissues / animals before being given to humans
Clinical trials / testing on human volunteers follow, to find the correct dose and confirm safety and effectiveness in people

Key terms in this question

medicine