Edexcel International A Level Biology

Revision Notes

4.7 Plant-Based Products for Sustainability

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Substituting Oil-Based Products

  • Sustainability refers to the use of resources in such a way that the requirements of the current generation are met without depleting these resources for future generations
  • This requires the use of renewable resources - which can be used without the resource running out
    • An example would be solar energy - it will not run out in our lifetime as the sun will continue to shine every day for several billion more years
  • Fossil fuels are an example of a non-renewable resource, as they could potentially run out if we use them too fast (since it takes millions of years for fossil fuels to form)
  • Sustainable practices are those that minimise the damage done to the environment and its resources, to ensure that there will be something left for the next generation
    • An example would be replanting trees after logging
  • Unsustainable practices are limited by a finite supply of resources
    • An example is the use of fossil fuels to make oil-based plastics

Plant fibres and sustainability

  • Using plant fibres to make products such as ropes and fabric is more sustainable than using oil-based plastics
  • Less fossil fuels are used and plants can be replanted for the next generation
  • Plant fibres are biodegradable, unlike most oil-based plastics, which means the products made from these fibres can be broken down by microbes to minimise environmental pollution
  • Extracting and processing oil is an expensive and difficult procedure compared to growing and processing plants, making plant-based products easier and cheaper to produce in developing countries
  • However, the ropes made from plant fibres are typically not as strong as plastic ones

Starch and sustainability

  • Plants store excess sugars as starch in their cells
  • Starch can be used to make bioplastics which is more sustainable than making oil-based plastics
  • It does not require as much fossil fuels to be burned to produce them and the crop plants can be replanted (renewable resource)
  • Starch can also be used to make bioethanol, which can be used as a fuel for vehicles
  • Using starch to produce biofuels is more sustainable than producing them from oil


  • Bioplastics are made from biological polymers e.g. starch and cellulose
  • There are multiple benefits to using bioplastics as a suitable replacement of traditional plastics
    • Sustainability: starch and cellulose are plant based materials which can be replaced at a sustainable rate; unlike oil based plastics which are made from non-renewable fossil fuels
    • Biodegradable: since bioplastics are made from biological material, it can be broken down by microorganisms; unlike oil based plastics which is generally not biodegradable
      • This could potentially decrease the amount of plastic pollution that is currently having a detrimental effect on the environment
  • Currently, there are several different types of bioplastics in use
    • Cellulose-based plastics are made from wood pulp and are mainly used as food wrappers (e.g. cellophane)
    • Thermoplastic starch which is a mixture of starch and other compounds, such as gelatine, to create a smooth and shiny plastic
      • This has been used with great success in the pharmaceutical industry to create easy to swallow capsules that contain drugs
    • Polylactic acid (PLA) produced from maize or sugar cane and have properties similar to polyethene
    • Poly-3-hydroxybutyrate (PHB) which is made from products of the sugar industry and used in ropes, bank notes and car parts
  • Bioplastics can be burned once they are no longer used to avoid the production of methane during decomposition
    • Methane is a much more potent greenhouse gas than the carbon dioxide released during combustion
    • An added advantage to burning is that the energy released can be utilised to generate electricity and produce more bioplastics
  • There are several challenges concerning the use of bioplastic
    • They do not always have the same useful properties as oil based plastics
    • Bioplastics are more expensive than oil based plastics
    • Using limited food crops to produce plastics (which do not feed the hungry) is a controversial subject in some parts of the world

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Author: Marlene

Marlene graduated from Stellenbosch University, South Africa, in 2002 with a degree in Biodiversity and Ecology. After completing a PGCE (Postgraduate certificate in education) in 2003 she taught high school Biology for over 10 years at various schools across South Africa before returning to Stellenbosch University in 2014 to obtain an Honours degree in Biological Sciences. With over 16 years of teaching experience, of which the past 3 years were spent teaching IGCSE and A level Biology, Marlene is passionate about Biology and making it more approachable to her students.