AQA GCSE Combined Science Foundation (8464), Foundation tier · Biology › Infection and response › Communicable diseases
Practise Fungal diseases. 5 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
Rose black spot is the fungal disease in the specification. You need to know what it looks like, how it spreads, why it reduces the plant's growth and how it is treated.
Key facts
Rose black spot = fungal disease of roses
Symptoms: purple or black spots on leaves; leaves turn yellow and drop early
Spread: by water or wind
Effect: less photosynthesis → less growth
Treatment: fungicides and/or remove and destroy affected leaves
Fungicide = chemical that kills fungi
Notes
What rose black spot is
A disease of roses caused by a fungus.
Symptoms: purple or black spots develop on the leaves. The leaves often turn yellow and drop early.
How it spreads
diagram
The fungus produces spores, which are spread in the environment by water (e.g. rain splashing from leaf to leaf) or by wind.
Spores that land on the leaves of a healthy rose can infect it.
The fungus can survive on fallen leaves, so fallen leaves can be a source of new infections.
Spores spread in wind and rain splashes; fallen leaves are a source of new infections.
Why it reduces growth
The spotted and yellow parts of the leaves have less chlorophyll, and leaves that have fallen off cannot photosynthesise at all.
So the plant carries out less photosynthesis, makes less glucose and grows less.
Treatment
Spray the plant with fungicides (chemicals that kill fungi).
Remove and destroy the affected leaves, including any that have fallen, so the fungus cannot spread to other leaves or plants.
Gardeners often use both methods together.
Antibiotics do not treat fungal diseases: they kill bacteria, not fungi.
How to answer each type of question
Recall: pathogen type, symptoms and spread
1 to 3 marksGrade 4
Name the pathogen type: a fungus.
Use the exact symptom words: purple or black spots, leaves turn yellow, leaves drop early.
For spread, give water and wind.
Example. Rose black spot is a disease of rose plants. (a) What type of pathogen causes rose black spot? (b) Describe how rose black spot is spread from one plant to another.
Show the model answerHide the model answer
(a) A fungus (1) (b) By water, e.g. rain splashing spores onto other leaves (1); by the wind carrying spores to other plants (1)
Describe and explain treatments
2 to 4 marksGrade 5
Give the two treatments: fungicide and removing and destroying affected leaves.
Explain each: the fungicide kills the fungus; destroying leaves stops the fungus spreading.
Example. Give two ways a gardener could treat roses with black spot. Explain how each way helps.
Show the model answerHide the model answer
Spray the roses with a fungicide (1), which kills the fungus (1). Remove and destroy the affected leaves (1), so the fungus cannot spread from them to healthy leaves (1).
Don’t lose marks
Saying black spot is caused by a virus or a bacterium. It is caused by a fungus.
Suggesting antibiotics or 'medicine' as a treatment. Use fungicides.
Writing 'remove the leaves' without 'destroy'. Leaves left lying on the ground can still spread the fungus.
Writing 'it stops photosynthesis'. It reduces photosynthesis.
More tips
Memory tricks
The name tells you the symptom: black spots on the leaves, which then turn yellow and fall off.
Fungi → fungicides; bacteria → antibiotics. Match the chemical to the pathogen.
Any plant disease that damages leaves: fewer or less green leaves → less photosynthesis → less glucose → less growth.
Exam technique
Use the precise symptom words: purple or black spots, leaves turn yellow, leaves drop early.
For 'explain why growth is reduced', always link to photosynthesis and glucose.
If a question gives a fungal disease you have not met, apply the same ideas: spread by water or wind, treated with fungicides and by removing infected parts.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
Name a fungal disease of plantsRose black spot is a fungal disease of roses.
Grade 4
Describe the symptoms of rose black spotPurple or black spots develop on the leaves, which often turn yellow and drop early.
Grade 4
State how rose black spot is spreadIt is spread in the environment by water (e.g. splashing rain) or by wind.
Grade 5
Describe how rose black spot is treatedUse fungicides and/or remove and destroy the affected leaves.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Rose black spot is a disease of rose plants. Give one way that rose black spot is spread.
By water or wind.
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy6 marks
Rose black spot is a disease of rose plants.
(a) What type of pathogen causes rose black spot? Tick (✓) one box.[1]
Bacterium
Fungus
Protist
Virus
(b) Describe what the leaves of a rose plant with black spot look like.[2]
(c) Give one way that rose black spot is spread.[1]
(d) Give two ways that a gardener could treat rose black spot.[2]
Show the answer and mark scheme
(a)Answer: Fungus
(b)
purple / black spots on the leaves
leaves turn yellow (and drop off early)
(c)Answer: By water or wind.
(by) water / rain
(by) wind
(d)
spray with a fungicide
remove and destroy the affected leaves
Question 2Medium6 marks
A gardener noticed black spot on some rose bushes. Many of the leaves turned yellow and fell off early.
(a) Explain why rose bushes with black spot grow less than healthy rose bushes.[3]
(b) The gardener collected the fallen leaves from the ground and burned them. Explain why this helps to stop black spot spreading.[2]
(c) Suggest why black spot spreads more quickly in wet weather.[1]
Show the answer and mark scheme
(a)
fewer leaves / less green leaf area / less chlorophyll
(so) less photosynthesis
(so) less glucose for respiration / for making new cells / for growth
(b)
the fallen leaves contain the fungus / spores
burning destroys the fungus, so it cannot be spread (by wind or water) to healthy leaves / plants
(c)
the fungus / spores are spread by water, e.g. rain splashes spores onto other leaves