Describe — 2 marks
A mobile phone manufacturer is assessing the environmental impact of producing a new smartphone. The company wants to understand all stages of the product's life, from raw material extraction through to disposal, to make it more sustainable.
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Describe what is meant by a life cycle assessment (LCA) of a product.
[2 marks]
Show mark scheme
- An assessment of the environmental impacts of a product throughout its entire life (1 mark)
- From raw material extraction/manufacture through use to final disposal/recycling (1 mark)
Calculate — 5 marks
A manufacturing company produces plastic water bottles. They are conducting a life cycle assessment (LCA) to compare the environmental impact of their current production method with a proposed sustainable alternative. The current method uses virgin plastic and generates 2.4 kg of CO₂ equivalent per bottle produced. The proposed method uses 60% recycled plastic and generates 0.9 kg of CO₂ equivalent per bottle. The company produces 500,000 bottles annually.
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(a) Calculate the total annual CO₂ equivalent emissions from the current production method for all bottles produced.
[2 marks]
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(b) Calculate the total annual CO₂ equivalent emissions from the proposed sustainable method for all bottles produced.
[2 marks]
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(c) Calculate the percentage reduction in CO₂ equivalent emissions if the company switches to the proposed sustainable method. Show your working.
[1 mark]
Show mark scheme
- (a) Correctly multiplies 2.4 kg by 500,000 (1 mark)
- (a) Correct answer of 1,200,000 kg or 1,200 tonnes of CO₂ equivalent (1 mark)
- (b) Correctly multiplies 0.9 kg by 500,000 (1 mark)
- (b) Correct answer of 450,000 kg or 450 tonnes of CO₂ equivalent (1 mark)
- (c) Correct calculation: (1,200,000 - 450,000) ÷ 1,200,000 × 100 = 62.5% reduction (1 mark)
Calculate — 2 marks
A manufacturing company produces plastic water bottles. During a life cycle assessment, they analyse the energy consumption at different stages: raw material extraction (450 MJ), manufacturing (320 MJ), transportation (85 MJ), and end-of-life recycling (120 MJ). The company wants to reduce their environmental impact and is considering switching to recycled plastic, which would reduce the extraction stage energy to 180 MJ.
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(a) Calculate the total energy consumption for the current production process of one water bottle.
[1 mark]
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(b) Calculate the percentage reduction in total life cycle energy consumption if the company switches to recycled plastic.
[1 mark]
Show mark scheme
- (a) Correct addition of all four stages: 450 + 320 + 85 + 120 = 975 MJ (allow 975 MJ or 975 megajoules)
- (b) Correct calculation of new total: 180 + 320 + 85 + 120 = 705 MJ, then (975 - 705) ÷ 975 × 100 = 27.7% (accept 27.7% or 28% or 0.277 or equivalent)
Suggest — 4 marks
A manufacturer produces reusable shopping bags made from organic cotton. The company claims these bags are more sustainable than single-use plastic bags. However, a life cycle assessment (LCA) shows that producing one organic cotton bag requires significantly more water and energy than manufacturing a plastic bag. The cotton bag must be reused approximately 150 times before its total environmental impact equals that of a single plastic bag.
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(a) Suggest why the initial production stage of the organic cotton bag has a greater environmental impact than a single-use plastic bag. (1 mark)
[1 mark]
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(b) Suggest two reasons why the reusable cotton bag becomes more sustainable than the plastic bag after 150 uses, considering the complete life cycle of both products. (2 marks)
[2 marks]
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(c) Suggest how a consumer's purchasing decision and usage pattern would need to change for the organic cotton bag to be a genuinely sustainable choice compared to the plastic alternative. (1 mark)
[1 mark]
Show mark scheme
- (a) Growing/cultivating organic cotton requires large amounts of water/irrigation
- (a) Processing and manufacturing the cotton into a bag requires significant energy input
- (a) Transportation of materials adds to the energy/carbon footprint
- (a) Any one of these valid points = 1 mark
- (b) Point 1: Plastic bags are single-use so their environmental impact is not distributed/amortized; the cotton bag's impact is spread over 150 uses, reducing impact per use
- (b) Point 2: After production, plastic bags require disposal/landfill space/cause pollution, whereas cotton bags can be reused multiple times without additional manufacturing
- (b) Point 2 alternative: Plastic bags persist in the environment causing long-term damage; cotton is biodegradable so end-of-life impact is lower
- (b) Point 2 alternative: Multiple plastic bags would need to be produced to replace one cotton bag over time, so cumulative production emissions are higher for plastic
- (b) Award 1 mark per distinct, valid reason (maximum 2 marks)
- (c) The consumer must actually reuse the cotton bag at least 150 times (or close to this threshold) to break even
- (c) The consumer must use it regularly/frequently enough to reach this number of uses within a reasonable timeframe
- (c) The consumer must not discard/replace the bag prematurely
- (c) The consumer should avoid purchasing multiple cotton bags unnecessarily
- (c) Any one of these valid points = 1 mark
Calculate — 2 marks
A life cycle assessment was conducted to compare the carbon footprint of producing paper bags versus plastic bags for a supermarket chain. Producing one paper bag releases 50 g of carbon dioxide into the atmosphere, while producing one plastic bag releases 15 g of carbon dioxide.
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(a) Calculate how many times more carbon dioxide is released when producing one paper bag compared to one plastic bag. Give your answer to one decimal place.
[1 mark]
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(b) The supermarket uses 10 000 bags per week. Calculate the total mass of carbon dioxide, in kilograms, that would be released per week if the supermarket used paper bags instead of plastic bags.
[1 mark]
Show mark scheme
- (a) 3.3
- (b) 350 kg (accept 350 000 g)
GCSE Perfect