Organic waste can be decayed anaerobically in a biogas generator to produce a useful biofuel.
The pie chart below shows the composition of a sample of biogas.

Gas Y is the main combustible fuel gas in the biogas. What is the chemical name of Gas Y?
Calculate the percentage of Gas Y in the biogas sample.
Name two groups of microorganisms that are responsible for the decomposition of organic matter.
Explain how a temperature increase from 10 ∘C10\text{ }^\circ\text{C}10 ∘C to 35 ∘C35\text{ }^\circ\text{C}35 ∘C affects the rate of decay by these microorganisms.
Practise AQA GCSE Biology Organisation of an ecosystem with exam-style questions for Foundation and Higher tier. 24 questions covering Levels of organisation, How materials are cycled, Decomposition (biology only), and Impact of environmental change (biology only) (HT only), matched to the AQA GCSE Biology (8461) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.