Himalayan balsam is a plant from Asia. It was introduced to the UK and now grows along many riverbanks.
Himalayan balsam grows up to 2 m tall and each plant produces up to 800 seeds. It dies back in winter and leaves the soil bare.
Scientists studied five sites along a river. The Table shows their results.
Table
| Site | Percentage cover of Himalayan balsam | Number of native plant species |
|---|---|---|
| A | 0 | 18 |
| B | 25 | 13 |
| C | 50 | 9 |
| D | 75 | 5 |
| E | 95 | 2 |
Describe the relationship shown in the Table.
Explain why the number of native plant species decreases as the percentage cover of Himalayan balsam increases.
When the Himalayan balsam dies back in winter, soil from the bare riverbank washes into the river.
Suggest how this could affect organisms living in the river.
Explain how the decrease in native plant species could affect the insects living along the riverbank.
Scientists have suggested releasing a fungus from Asia that infects Himalayan balsam.
Give one risk of releasing this fungus.
38 exam-style questions on Edexcel GCSE Biology 9.2 Energy transfer and biodiversity, covering 9.2.1 Energy transfer between trophic levels, 9.2.2 Efficiency of energy transfers, 9.2.3 Human interactions and biodiversity, 9.2.4 Benefits of maintaining biodiversity, and 9.2.5 Biological factors affecting food security. Each one has a worked solution and a mark scheme showing where the marks go.