AQA GCSE Combined Science Foundation (8464), Foundation tier · Chemistry › Using resources › Life cycle assessment and recycling
Practise Life cycle assessment. 9 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
How a life cycle assessment (LCA) measures the environmental impact of a product at each stage of its life, why an LCA is not completely objective, and how to compare products such as plastic and paper shopping bags. Questions on Paper 2 often give you a table of data to interpret, calculate from and evaluate.
Key facts
LCA stages: raw materials → manufacturing and packaging → use → disposal (+ transport at each stage)
Easy to quantify: water, resources, energy sources, some wastes
Plastic bag: from crude oil (finite), reused many times, not biodegradable
Paper bag: from trees (renewable), reused fewer times, biodegradable
Impact per use = total impact ÷ number of uses
Notes
The stages of an LCA
diagram
A life cycle assessment (LCA) assesses the environmental impact of a product at each stage of its life:
1. Extracting and processing raw materials (e.g. mining ores, drilling for crude oil, felling trees).
2. Manufacturing and packaging.
3. Use and operation during its lifetime (e.g. fuel or electricity used, how many times it is reused).
4. Disposal at the end of its useful life (landfill, incineration or recycling).
Transport and distribution at each stage are included too.
Assess the impact at every stage, including transport between them.
What can and cannot be measured
Fairly easy to measure: the use of water, resources and energy sources, and the production of some wastes (e.g. mass of carbon dioxide released).
Plastic and paper shopping bags
Plastic bags (poly(ethene)) are made from crude oil, a finite resource. They are light, strong and can be reused many times. They are not biodegradable, so they last a long time in landfill or as litter, but they can be recycled.
Paper bags are made from trees, a renewable resource. In most LCAs, making a paper bag uses more energy than making a plastic bag, and paper bags are heavier to transport. They are weaker, so they are reused fewer times, but they are biodegradable and easily recycled.
Which bag has the lower impact depends on the data, especially how many times each bag is used. Compare them per use.
How to answer each type of question
Name and apply the stages of an LCA
1 to 4 marksGrade 4
Learn the four stages in order.
Link each stage to the product in the question with a specific example.
Remember that transport happens at every stage.
Example. A company carries out a life cycle assessment for glass drinks bottles. Give two stages of the life cycle assessment. For each stage, give one environmental impact of the bottles at that stage. (4 marks)
Show the model answerHide the model answer
Any two stages, each with a matching impact, e.g.: extracting raw materials (1): quarrying sand and limestone damages the landscape (1); manufacturing (1): heating the furnace burns fuel, releasing carbon dioxide (1); use (1): heavy bottles need a lot of fuel to transport / washing for reuse uses water and energy (1); disposal (1): bottles in landfill take up space / recycling uses energy for collection and melting (1).
Don’t lose marks
Forgetting transport, or missing out the use stage.
Saying paper bags are always better 'because they are biodegradable', ignoring manufacture and the number of uses.
Comparing total impacts for products that are used a different number of times. Divide by the number of uses.
Saying an LCA is 'unreliable' when you mean it is not fully objective because it needs value judgements.
More tips
Memory tricks
An LCA is a life story: 'born' (raw materials), 'made' (manufacture), 'lives' (use), 'dies' (disposal), with a journey (transport) between each.
Things you can measure are objective; harm you have to judge needs value judgements.
Always compare per use: a bag used 20 times spreads its impact over 20 trips.
If only one stage is shown, suspect a selective LCA.
Exam technique
When given an LCA table, quote the numbers and do the arithmetic; 'evaluate' also needs a conclusion.
Bring in your own knowledge where asked: finite or renewable raw materials, biodegradability, recycling.
In 'explain' questions about LCAs, 'value judgements' is the key phrase examiners look for.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
Name the four stages of an LCAExtracting and processing raw materials, manufacturing and packaging, use and operation, and disposal.
Grade 4
State what an LCA is used forTo assess the environmental impact of a product over its whole life, including transport at each stage.
Grade 5
Compare plastic and paper bags using an LCAPlastic bags come from crude oil (finite) but can be reused many times; paper bags come from trees but are reused less.
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Life cycle assessments (LCAs) are carried out to assess the environmental impact of products.
(a) Which of these is not one of the stages assessed in an LCA? Tick (✓) one box.[1]
Extracting and processing raw materials
Manufacturing and packaging
Advertising the product
Disposal at the end of its useful life
(b) Give two things that can be measured fairly easily in an LCA.[2]
(c) Explain why an LCA is not a purely objective process.[1]
Show the answer and mark scheme
(a)Answer: Advertising the product
(b)
use of water
use of resources / raw materials
use of energy (sources)
production of (some) wastes
(c)
allocating numerical values to the effects of pollutants requires value judgements
Question 2Medium5 marks
A company selling disposable nappies used an LCA in an advertisement. The LCA included only the use and disposal stages.
(a) Suggest why this LCA could be misleading.[2]
(b) Suggest who should carry out an LCA so that the results can be trusted.[1]
(c) Transport and distribution are included at each stage of an LCA. Explain why transport adds to the environmental impact of a product.[1]
(d) Explain why it is difficult to give numerical values to the effects of pollutants in an LCA.[1]
Show the answer and mark scheme
(a)
it leaves out stages (e.g. extracting raw materials, manufacturing, transport) that may have large environmental impacts
selective / shortened LCAs can be used to reach a pre-determined conclusion (e.g. to support advertising claims)
(b)
an independent organisation / scientists with no connection to the company