GCSE BIOLOGY; When does digestion come in to the ethanol-based fuels production from plant materials?

the question is ---Describe, as fully as you can, how ethanol-based fuels are produced from plant materials.



in the mark scheme, it gives you a mark for saying the word digestion but where does that come into the production, im really confused??



thanks



Answer on GCSE BIOLOGY; When does digestion come in to the ethanol-based fuels production from plant materials?



I do GCSE biology as well. There are two ways in order to obtain ethanol based fuels:

1) Sugar cane is cut down; this sugar cane contains many simple sugars such as glucose. A yeast culture is added to the sugar cane and the yeast respires anaerobically, thus, producing ethanol, this process is fermentation. Unfortunately, this ethanol is mixed with other things that is not wanted, as a result, fractional distillation occurs which separates the mixture and leaves ethanol in a pure form

2) Maize is ploughed from a field. Maize is made out of complex carbohydrates, which yeast can not break down as a fuel source, as a result, carbohydrase enzymes are added to convert it into simple sugars. After this, yeast is added and the process of fermentation occurs, then fractional distillation.



Generally, the ethanol is mixed petrol to produce a petrol-ethanol fuel that can be used in most engines. The advantage of ethanol fuels is that it is a renewable source of energy that can be easily produced. Additionally, it is carbon neutral as the growing plants take in CO2 even though they release CO2 during combustion. Finally, the fuel rarely emits harmful products such as sulphur and particulates as it is a cleaner fuel.

Digestion is the conversion of maize to simple sugars

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