The passage describes the process of water pollution and eutrophication in an aquatic ecosystem. Complete the passage by writing a suitable word or words in each of the spaces.
When agricultural fertilisers enter a river or lake, usually by the process of [1] _______________\text{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_}_______________, they enrich the water with mineral ions such as [2] _______________\text{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_}_______________. This enrichment leads to the rapid growth of [3] _______________\text{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_}_______________ at the surface, forming a bloom.
If untreated organic waste, such as human sewage containing [4] _______________\text{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_}_______________, is discharged into the water, it acts as an abundant food source. Aquatic [5] _______________\text{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_}_______________ decompose this waste using aerobic [6] _______________\text{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_}_______________. This process severely reduces the concentration of dissolved [7] _______________\text{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_}_______________ in the water, making it difficult for fish and other large organisms to survive.
44 exam-style questions on Edexcel IGCSE Biology Human influences on the environment. Each one has a worked solution and a mark scheme showing where the marks go.