Vines on a slope above a reservoir are treated with fertiliser. Some of the fertiliser is not taken up by the vines. After heavy rain, runoff from the vineyard enters the reservoir, where algae become more abundant.
Which explanation best accounts for the increase in algae?
Runoff carries surplus fertiliser into the reservoir, supplying algae with mineral ions they need for growth.
The vines take up the fertiliser and release it into the reservoir, where algae absorb it.
Runoff carries surplus fertiliser into the reservoir, where it helps algae take up more water and grow.
Runoff carries surplus fertiliser into the reservoir, where algae use it as a source of energy for growth.
127 exam-style questions on OCR GCSE Biology 6.2 Feeding the human race, covering 6.2.1 Biological factors affecting food security, 6.2.2 Agricultural solutions to growing demand, 6.2.3 Selective breeding, 6.2.4 Genetic engineering, 6.2.5 Steps in genetic engineering, 6.2.6 Benefits and risks of gene technology in agriculture, and 6.2.7 Biotechnological solutions to growing demand. Each one has a worked solution and a mark scheme showing where the marks go.