Fertiliser spread on grass at a sports centre is washed into a nearby lake after rain. A dense algal bloom forms. Soon afterwards, many submerged plants die.
Which statement best explains why the submerged plants die?
The algae block light, so the submerged plants cannot photosynthesise enough to survive.
The extra nitrate prevents the submerged plants absorbing magnesium needed to make chlorophyll.
The algae use dissolved oxygen for photosynthesis, so the submerged plants cannot respire.
The extra nitrate makes the submerged plants photosynthesise too quickly, which kills them.
100 exam-style questions on Edexcel GCSE Biology 4.3 Selective breeding and genetic modification, covering 4.3.1 Selective breeding and its impact, 4.3.2 Tissue culture, 4.3.3 Genetic engineering overview, 4.3.4 Main stages of genetic engineering, 4.3.5 Advantages and disadvantages of GM organisms, 4.3.6 Agricultural solutions for a growing population, and 4.3.7 Evaluating genetic engineering and breeding. Each one has a worked solution and a mark scheme showing where the marks go.