Rose black spot: loss of working leaf area
| English | 中文 | Pinyin |
|---|---|---|
| fungal disease/ˈfʌŋɡl dɪˈziːz/ | 真菌病 | zhēn jūn bìng |
| fungicide/ˈfʌŋɡɪsaɪd/ | 杀真菌剂 | shā zhēn jūn jì |
What would explain this observation?
- A rose can lose growth without being eaten. Diseased leaves may yellow and fall before the plant has finished using them for photosynthesis.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Rose black spot is a fungal disease 真菌病. Purple or black spots develop on leaves, which often turn yellow and fall early. The reduction in functioning leaves reduces photosynthesis, so less glucose is available for growth. The disease spreads in the environment through water or wind.
- fungal disease: Disease caused by a pathogenic fungus; fungicide 杀真菌剂: A substance used to control fungi.
How can early loss of leaves reduce growth?
Removing and destroying affected leaves can reduce infectious material. Appropriate fungicides are another specified control, but school work follows teacher-approved handling and disposal. A control aimed at a fungus is distinct from treating bacterial disease. The effect on growth is explained through leaf function rather than simply saying that spots look unhealthy.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Removing and destroying affected leaves can reduce infectious material. Appropriate fungicides are another specified control, but school work follows teacher-approved handling and disposal. A control aimed at a fungus is distinct from treating bacterial disease. The effect on growth is explained through leaf function rather than simply saying that spots look unhealthy.
- Use supplied rose photographs and fictional growth data. Record the visible symptoms separately from an inferred cause, because spots alone can have other causes. Compare matched plants with the same variety, water, light and observation time. Do not spray chemicals or transfer diseased material without school supervision.
Which two habits make the investigation or model in this case more defensible?
Use supplied rose photographs and fictional growth data. Record the visible symptoms separately from an inferred cause, because spots alone can have other causes. Compare matched plants with the same variety, water, light and observation time. Do not spray chemicals or transfer diseased material without school supervision.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a model plant begins with 24 functioning leaves and loses 6 early. It retains 18, or 18/24×100 = 75% of the initial leaf count. Leaf count is only a rough indicator: leaves may have different areas, ages and levels of damage, so it cannot by itself give an exact photosynthesis rate.
A model plant retains 15 of its original 20 functioning leaves. Calculate the percentage retained. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A model plant retains 15 of its original 20 functioning leaves. Calculate the percentage retained.
The result is 75 %. Known: a model plant begins with 24 functioning leaves and loses 6 early. It retains 18, or 18/24×100 = 75% of the initial leaf count. Leaf count is only a rough indicator: leaves may have different areas, ages and levels of damage, so it cannot by itself give an exact photosynthesis rate.
Check the conclusion and its limits
- Black spot is fungal, not the same pathogen as TMV. A fallen diseased leaf may still be a source of spread. A correlation between leaf loss and lower growth needs a mechanism and suitable comparison, and remaining leaf number is not a direct measure of glucose production.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Every leaf spot proves infection by TMV. This claim is false: Black spot is fungal, not the same pathogen as TMV. A fallen diseased leaf may still be a source of spread. A correlation between leaf loss and lower growth needs a mechanism and suitable comparison, and remaining leaf number is not a direct measure of glucose production.
Rose black spot: loss of working leaf area: Removing and destroying affected leaves can reduce infectious material. Appropriate fungicides are another specified control, but school work follows teacher-approved handling and disposal. A control aimed at a fungus is distinct from treating bacterial disease. The effect on growth is explained through leaf function rather than simply saying that spots look unhealthy.
Every leaf spot proves infection by TMV.
Black spot is fungal, not the same pathogen as TMV. A fallen diseased leaf may still be a source of spread. A correlation between leaf loss and lower growth needs a mechanism and suitable comparison, and remaining leaf number is not a direct measure of glucose production.
Disease caused by a pathogenic fungus: write the technical term.
fungal disease means Disease caused by a pathogenic fungus.