Plants can be infected by pathogens.
The Table shows information about three plant diseases.
Table
| Disease | Type of pathogen | How the pathogen is spread |
|---|---|---|
| tobacco mosaic disease | virus | by contact between leaves of infected and healthy plants |
| barley powdery mildew | fungus | by spores carried in the wind |
| crown gall disease | bacterium | from the soil, through wounds in the roots or stem |
Tobacco mosaic virus (TMV) causes pale, discoloured patches on the leaves.
Suggest why plants infected with TMV grow more slowly than healthy plants.
Use the Table to suggest one way a farmer could reduce the spread of barley powdery mildew in a field of barley.
Plants have physical defences against pathogens.
Describe how the leaf cuticle and the cell wall help to protect a plant against pathogens.
Some plants make antimicrobial substances.
Give the type of plant defence that this is.
181 exam-style questions on OCR GCSE Biology 6.3 Monitoring and maintaining health, covering 6.3.1 Health and disease, 6.3.2 Interactions between diseases, 6.3.3 Spread of communicable diseases, 6.3.4 Common infections and diseases, 6.3.5 Physical plant defence responses, 6.3.6 Chemical plant defence responses, 6.3.7 Detecting and identifying plant diseases, 6.3.8 White blood cells and platelets, 6.3.9 Non-specific defence systems, 6.3.10 The immune system, 6.3.11 Monoclonal antibodies, 6.3.12 Vaccines and medicines, 6.3.13 Aseptic techniques, 6.3.14 Discovery and development of new medicines, 6.3.15 Causes of non-communicable diseases, 6.3.16 Treatments for cardiovascular disease, 6.3.17 Lifestyle factors and non-communicable diseases, 6.3.18 Cancer, 6.3.19 Stem cells in medicine, 6.3.20 Gene technology in medicine, and 6.3.21 The human genome and medicine. Each one has a worked solution and a mark scheme showing where the marks go.