What are pathogens, and how are communicable diseases spread and prevented?
Pathogens as disease-causing microorganisms, the types of pathogen, how communicable diseases spread, and how their spread is reduced.
A focused answer to the WJEC GCSE Science Double Award Unit 4 topic on disease, covering pathogens and the types (bacteria, viruses, fungi, protists), how communicable diseases are spread, and how their spread can be reduced.
Reviewed by: AI editorial process; not yet individually human-reviewed
Have a quick question? Jump to the Q&A page
Jump to a section
What this dot point is asking
WJEC Double Award Unit 4 wants you to describe pathogens and their types, explain how communicable diseases spread, and describe how their spread can be reduced.
What pathogens are
Not all microorganisms are harmful; only pathogens cause disease. Pathogens make us ill either by damaging cells or by producing toxins (poisons).
The four types of pathogen
How communicable diseases spread
Communicable diseases can be passed on in several ways:
- Through the air: breathing in droplets from coughs and sneezes (e.g. flu, colds).
- By direct contact: touching an infected person or surface (e.g. athlete's foot).
- In contaminated food or water: eating or drinking something carrying the pathogen (e.g. cholera, food poisoning).
- By a vector: an animal (such as a mosquito) that carries the pathogen from one host to another (e.g. malaria).
Reducing the spread
The spread of disease can be reduced by:
- Good hygiene: washing hands, using disinfectant, covering coughs and sneezes.
- Isolating infected people so they cannot pass it on.
- Vaccination to make people immune.
- Destroying vectors (for example killing mosquitoes or using nets).
- Treating water and cooking food to remove pathogens.
How pathogens make us ill
Pathogens cause the symptoms of disease in two main ways. Bacteria reproduce rapidly inside the body and release toxins (poisons) that damage cells and tissues, which causes symptoms such as fever and pain. Viruses get inside the body's cells and reproduce there, then burst out, damaging or killing the cells. Knowing how each type causes harm helps explain why bacterial and viral diseases are treated differently, and why antibiotics (which target bacteria) cannot treat viral diseases.
Disease in plants too
Pathogens affect plants as well as animals, which is important for farming. Plant diseases can be caused by fungi (such as rose black spot), bacteria and viruses (such as tobacco mosaic virus, which discolours leaves). Signs of plant disease include discoloured or spotted leaves, stunted growth and rotting. Plant diseases spread through soil, air and by insects, and they reduce crop yields, so detecting and controlling them matters for food production. Recognising that the same types of pathogen attack plants is a useful extension often tested in exams.
Try this
Q1. Name the type of pathogen that causes athlete's foot. [1 mark]
- Cue. A fungus.
Q2. Give one way a disease can be spread through the air. [1 mark]
- Cue. Breathing in droplets from coughs or sneezes.
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC style4 marksName the four types of pathogen and give one disease caused by each.Show worked answer →
A Unit 4 recall question worth 4 marks (1 each). Reward: bacteria cause diseases such as food poisoning, tuberculosis or cholera (1); viruses cause measles, influenza (flu), HIV or the common cold (1); fungi cause athlete's foot or ringworm (1); protists (protozoa) cause malaria (1). Markers credit each pathogen type with a correct disease. A common error is to call a virus a bacterium, or to give a non-communicable disease such as cancer.
WJEC style4 marksDescribe four ways the spread of communicable diseases can be reduced.Show worked answer →
A Unit 4 application question worth 4 marks. Reward any four of: good hygiene (washing hands, using disinfectant) (1); isolating infected people to stop them passing it on (1); vaccination to make people immune (1); destroying vectors such as mosquitoes (or using nets) (1); safe food and water (cooking food, treating water); and safe sex / not sharing needles for some diseases (1). Markers credit four valid methods. A common error is to repeat the same method in different words.
Related dot points
- The body's defences against pathogens, including physical and chemical barriers and the role of white blood cells.
A focused answer to the WJEC GCSE Science Double Award Unit 4 topic on body defences, covering the physical and chemical barriers that keep pathogens out and how white blood cells defend the body by engulfing pathogens and producing antibodies.
- How vaccination produces immunity, how antibiotics treat bacterial infections, and the problem of antibiotic resistance.
A focused answer to the WJEC GCSE Science Double Award Unit 4 topic on vaccines and antibiotics, covering how vaccination produces immunity, how antibiotics treat bacterial infections but not viruses, and the problem of antibiotic resistance.
- Culturing microorganisms on agar, the use of aseptic technique to avoid contamination, and the related practical.
A focused answer to the WJEC GCSE Science Double Award Unit 4 topic on culturing microorganisms, covering how microorganisms are grown on agar, the use of aseptic technique to avoid contamination, and the practical investigating the effect of antiseptics or antibiotics.
- The carbon cycle and the nitrogen cycle, the role of decomposers and named bacteria, and how human activity affects these cycles and biodiversity.
A focused answer to the WJEC GCSE Science Double Award Unit 1 topic on nutrient cycles, covering the carbon cycle, the nitrogen cycle and the bacteria involved, the role of decomposers, and how human activity affects the cycles and biodiversity.