10.6 Life cycle assessments
5 exam questions worth 10 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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Which is the first stage of a life cycle assessment?
Choose one answer.
Correct Not quite: the answer is Extracting and processing raw materials
Mark scheme
A
Model answer
A: the LCA starts with extracting and processing raw materials.
Give the four stages considered in a life cycle assessment.
Mark scheme
- raw materials, manufacture (1)
- use, disposal (1)
Model answer
Extracting and processing raw materials; manufacturing and packaging; use; disposal.
Explain why life cycle assessments are not always objective.
Mark scheme
- the effects of some pollutants are difficult to give a value to (1)
- so value judgements are needed / LCAs can be selective or biased (1)
Model answer
It is hard to put numbers on the effects of some pollutants, so value judgements are made, and a company may use a selective LCA to favour its product.
Compare the environmental impact of paper bags and plastic bags using a life cycle approach.
Mark scheme
- raw materials: paper from renewable timber; plastic from finite crude oil (1)
- manufacture: paper uses more energy and water (1)
- use: plastic bags can be reused many times (1)
- disposal: paper is biodegradable; plastic is not but can be recycled (1)
Model answer
Paper bags come from renewable timber, while plastic bags use finite crude oil. Making paper bags uses more energy and water. Plastic bags can be reused many times, while paper bags are usually used once. Paper is biodegradable, but plastic lasts a long time in landfill, although both can be recycled.
Suggest why a supermarket might use only part of a life cycle assessment in its advertising.
Mark scheme
- to show its product in a favourable way / selective use of data / bias (1)
Model answer
To make its product look better by leaving out the stages where it has a larger impact.
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