Plant fibres, starch and sustainabilitySpec 4.7
In short
Sustainability means meeting present needs without harming the ability of future generations to meet theirs. Plant fibres and starch are renewable and can be grown again, and products made from them are often biodegradable. They can replace oil-based plastics, which come from a finite resource and may persist in the environment.
Oil-based plastics are made from crude oil, a finite resource, and most do not break down quickly, so they build up as waste. Plant-based materials offer alternatives that can contribute to sustainability, which means meeting the needs of the present without harming the ability of future generations to meet their own needs.
| Material | Source | Example uses |
|---|---|---|
| Plant fibres (hemp, flax, jute, sisal) | Sclerenchyma fibres from stems and leaves | Rope, string, textiles, bags, and fibre-reinforced materials used in place of plastic or glass fibre composites |
| Starch-based plastics | Starch from crops such as maize, potato or cassava | Packaging, carrier bags, cutlery, food containers, loose-fill packaging |
How they contribute to sustainability
- They are renewable: new crops can be grown each year.
- Plants take in carbon dioxide during photosynthesis, so the carbon released when products are used or break down was recently removed from the atmosphere. This can reduce net carbon dioxide emissions compared with using oil.
- They are often biodegradable, so microorganisms can break them down and less waste accumulates.
- Less crude oil is needed, which reduces the use of a finite resource.
Limitations
- Growing crops for materials needs land, water and fertiliser, which can compete with food production and reduce biodiversity if natural habitat is cleared.
- Some starch-based plastics break down only under particular conditions, such as in industrial composting, and may be less strong or less waterproof than oil-based plastics.
- Processing and transport still use energy.
A balanced answer scores best: give one or two points on renewability or biodegradability and a limitation such as land use competing with food crops.
Written and checked against the Edexcel International AS Level Biology (XBI11) specification · Updated October 2026