AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Students should be able to explain how diseases caused by viruses,…
Full specification wording
Communicable (infectious) diseases: Students should be able to explain how diseases caused by viruses, bacteria, protists and fungi are spread in animals and plants.
Communicable diseases are caused by pathogens and can pass from one organism to another.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 1 of 8
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Communicable diseases are caused by pathogens and can pass from one organism to another. Viruses spread in animals through droplets, direct contact, contaminated food or water, and blood or body fluids; in plants they spread through vectors such as aphids and by cuttings or grafting. Bacteria spread in animals through contaminated food and water, direct contact and droplets; in plants through wounds, water and vectors. Protists are often spread by vectors, such as mosquitoes carrying malaria, or by water; in plants they may enter through roots or wounds. Fungi spread by spores carried in air, water or on surfaces, and by direct contact; in plants fungal spores often enter through leaves or wounds. A useful method is to name the pathogen type, the route and one control measure.
What earns the marks
- Viruses spread in animals by droplets, direct contact, contaminated food or water, and blood or body fluids; in plants by vectors such as aphids and by cuttings or grafting.
- Bacteria spread in animals by contaminated food and water, direct contact and droplets; in plants through wounds, water and vectors.
- Protists spread mainly by vectors such as mosquitoes, and by contaminated water; in plants they can enter through roots or wounds.
- Fungi spread by spores carried in air, water or on surfaces, and by direct contact; in plants spores often enter through leaves or wounds.
- Each explanation should link a named pathogen type to a specific route of spread in either an animal or a plant.
- Control measures such as hygiene, vector control and quarantine can be linked to interrupting the named route.
Common mistakes and how to put them right
Treating all pathogens as spreading in the same way.
Put it right: Viruses, bacteria, protists and fungi have different routes and vectors.
Confusing a vector with a pathogen.
Put it right: A vector such as a mosquito carries a pathogen but is not itself the disease-causing organism.
Giving only a disease name without naming the pathogen type or route of spread, which does not explain transmission.
Exam tips
- Structure answers as pathogen type, route of spread and one control measure to cover the explanation fully.
- Use named examples such as influenza virus, Salmonella bacteria, malaria protist and athlete's foot fungus to make routes concrete.
- For plant diseases, mention vectors such as aphids and entry through wounds or leaves rather than repeating animal routes.
Try the lesson
The start of the Communicable (infectious) diseases: Students should be able to explain how diseases caused by viruses, bacteria, protists and fungi are spread in animals and plants. lesson, made from checked teaching notes for this specification point.
Have a go first
A student has a cold caused by a virus. Which way is this viral disease most likely to be passed from the student to a classmate?
Listen
Communicable diseases are caused by pathogens and can pass from one organism to another. Viruses spread in animals through droplets, direct contact, contaminated food or water, and blood or body fluids; in plants they spread through vectors such as aphids and by cuttings or grafting. Bacteria spread in animals through contaminated food and water, direct contact and droplets; in plants through wounds, water and vectors. Protists are often spread by vectors, such as mosquitoes carrying malaria, or by water; in plants they may enter through roots or wounds. Fungi spread by spores carried in air, water or on surfaces, and by direct contact; in plants fungal spores often enter through leaves or wounds. A useful method is to name the pathogen type, the route and one control measure. A strong answer earns marks for these points. Viruses spread in animals by droplets, direct contact, contaminated food or water, and blood or body fluids; in plants by vectors such as aphids and by cuttings or grafting. Bacteria spread in animals by contaminated food and water, direct contact and droplets; in plants through wounds, water and vectors. Protists spread mainly by vectors such as mosquitoes, and by contaminated water; in plants they can enter through roots or wounds. Fungi spread by spores carried in air, water or on surfaces, and by direct contact; in plants spores often enter through leaves or wounds. Exam tip: Structure answers as pathogen type, route of spread and one control measure to cover the explanation fully.
Key words
Say what each word means before you turn the card.
Pathogens
Try answering aloud or in your head before turning the card.
Communicable diseases
Try answering aloud or in your head before turning the card.
Vectors
Try answering aloud or in your head before turning the card.
Spores
Try answering aloud or in your head before turning the card.
See every definition
- Pathogens
- Organisms that cause communicable diseases, which can pass from one organism to another.
- Communicable diseases
- Diseases caused by pathogens that can pass from one organism to another.
- Vectors
- Carriers such as aphids and mosquitoes that spread pathogens but are not themselves the disease-causing organism.
- Spores
- Structures by which fungi spread, carried in air, water or on surfaces, and often entering plants through leaves or wounds.
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Communicable (infectious) diseases: Students should be able to explain how diseases caused by viruses, bacteria, protists and fungi are spread in animals and plants.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge