Pearson Edexcel · GCSE · Biology
Course version: 1BI0 · Version from Sept 2016
5.10B Describe how plants defend themselves against attack from pests and…
Full specification wording
Topic 5 – Health, disease and the development of medicines: 5.10B Describe how plants defend themselves against attack from pests and pathogens by producing chemicals, some of which can be used to treat human diseases or relieve symptoms
Plants cannot move away from a pest or pathogen, so many defend themselves chemically.
Checked against the Pearson Edexcel 1BI0 specification (opens in a new tab) on .
- Point 10 of 21
Study notes
From the checked teaching notes for this specification point.
The idea
Plants cannot move away from a pest or pathogen, so many defend themselves chemically. When attacked, a plant may produce substances that are toxic to the insect or microorganism, or that deter feeding and slow invasion. These defensive chemicals are the plant's chemical barrier, working alongside physical features such as waxy cuticles and cell walls. Some of these same chemicals are valuable to humans: for example, the compound aspirin was originally derived from a chemical found in willow bark, and quinine used to treat malaria comes from cinchona bark. So a plant chemical that harms a pathogen or pest can, when extracted and used as a medicine, treat a human disease or relieve symptoms such as pain or fever. A multiple-choice question may ask why a plant produces such a chemical, or how a plant chemical can become a medicine.
What earns the marks
- Plants defend against pests and pathogens by producing chemicals that are toxic to, or deter, the attacking organism.
- Some plant chemicals can be extracted and used as medicines to treat human diseases.
- Some plant chemicals are used to relieve symptoms such as pain or fever rather than cure disease.
- A correct answer links the plant's defensive chemical production to a human medical use of the same or a similar substance.
Common mistakes and how to put them right
Thinking plants defend only by physical barriers such as thorns.
Put it right: They also produce defensive chemicals against pests and pathogens.
Assuming every plant chemical is harmless to humans.
Put it right: Some are toxic to pests and pathogens but others can be used as medicines.
Confusing relieving symptoms with curing disease.
Put it right: Some plant chemicals treat disease while others only relieve symptoms such as pain.
Exam tips
- Read the question stem to see whether it asks about defence against pests, against pathogens, or about medical use.
- Eliminate options that say plants cannot defend themselves chemically.
- Check whether an option describes treating a disease or only relieving symptoms, and match it to the wording of the question.
Try the lesson
The start of the Topic 5 – Health, disease and the development of medicines: 5.10B Describe how plants defend themselves against attack from pests and pathogens by producing chemicals, some of which can be used to treat human diseases or relieve symptoms lesson, made from checked teaching notes for this specification point.
Have a go first
Some plants defend themselves against pests and pathogens by producing chemicals. What effect can these plant chemicals have on the pests or pathogens?
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