1
Triple onlyHigher tier
[3 marks]A gardener notices spots on the leaves of a plant and some stunted growth. (a) State one other sign that a plant may have a disease. (1) (b) Describe two ways the gardener could identify the disease. (2)
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- any one from: areas of decay (rot) / growths / malformed stems or leaves / discolouration / presence of pests (1)
- reference to a gardening manual or website (1)
- taking the plant to a laboratory to identify the pathogen (1)
- using a testing kit containing monoclonal antibodies (1)
- Max 3 (award (b) for any two)
2
Triple only
[2 marks]A farmer finds that a crop shows stunted growth. A soil test shows a lack of nitrate ions. Explain why a lack of nitrate ions causes stunted growth.
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- nitrate ions are needed for protein synthesis (1)
- less protein made, so less growth (1) allow fewer new cells made
3
Triple only
[1 mark]A plant has yellow leaves because it cannot make enough chlorophyll. Which ion is lacking?
- Sodium
- Magnesium
- Calcium
- Phosphate
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Answer: B B (1) (chlorosis is caused by magnesium deficiency)
4
Triple only
[6 marks]Describe how plants defend themselves against pathogens and against being eaten by animals.
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| Level | Marks | What the answer does |
|---|---|---|
| 3 | 5–6 | A clear, detailed description of physical, chemical and mechanical defences, with correct examples of each and the purpose of each stated (resisting invasion by microorganisms or deterring animals). |
| 2 | 3–4 | A description of at least two types of defence with some correct examples, but limited detail about their purpose. |
| 1 | 1–2 | One or two simple examples of plant defences with little or no explanation. |
Indicative content
- physical: cellulose cell walls, tough waxy cuticle on leaves, layers of dead cells around stems (bark) which fall off
- these resist invasion of microorganisms
- chemical: antibacterial chemicals; poisons to deter herbivores
- mechanical: thorns and hairs deter animals
- leaves that droop or curl when touched
- mimicry to trick animals