Detection and identification of plant diseases — AQA GCSE Biology
Test yourself on Detection and identification of plant diseases with AQA GCSE practice questions.
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Detection and identification of plant diseases explained
Once a plant shows disease symptoms, a grower must work out the cause before choosing a treatment.
Read the full explanation
A gardener can compare the visible signs, such as leaf spots or distorted growth, with photographs and descriptions in a gardening manual or a reliable website; this is quick and free but depends on correct matching. If the cause is unclear, a sample of the infected plant can be sent or taken to a laboratory, where specialists culture or examine the pathogen and identify it accurately. Testing kits containing monoclonal antibodies are also used: the antibodies bind only to a specific pathogen antigen, giving a rapid result, often on a dipstick. Each method trades speed, cost and accuracy, so the choice depends on the situation.
Your focus
- Describe how a gardening manual or website can be used to identify a plant disease from symptoms.
- Explain how laboratory testing and monoclonal antibody test kits identify plant pathogens.
- Compare the three identification methods in terms of speed, cost and accuracy.
Detection and identification of plant diseases exam tips
Marking Points
- Reference sources such as a gardening manual or website allow a grower to match visible symptoms to a likely cause without specialist equipment.
- Laboratory identification involves sending or taking infected plant material so that a specialist can identify the pathogen directly.
- Testing kits use monoclonal antibodies that bind specifically to antigens of the target pathogen, giving a rapid and specific result.
- Monoclonal antibodies are produced from a single clone of cells, so they are identical and bind to one specific antigen.
- The three methods differ in speed, cost and reliability, so the most suitable method depends on the context.
- Identification is needed before appropriate control measures can be chosen, because different pathogens need different treatments.
Examiner Tips
- 💡Link each method to a practical advantage or limitation, such as speed, cost or accuracy, rather than listing methods alone.
- 💡When describing test kits, name monoclonal antibodies and explain specific binding to pathogen antigens.
- 💡Apply the methods to a scenario, for example advising a gardener who finds spotted leaves on a tomato plant.
Common Mistakes
- Thinking any antibody will detect any pathogen; correction: monoclonal antibodies are specific, so a kit detects only the pathogen whose antigen matches the antibody.
- Assuming laboratory testing is always the first step; correction: a manual or website is often used first because it is quick and cheap, with laboratory testing reserved for uncertain cases.
- Confusing identification with treatment; correction: identification establishes the cause, and treatment is a separate later decision.