# A scientist is developing new packaging materials. She tests two samples: one made from a synthetic polymer called polythene, and one made from a biopolymer called starch. Explain why polythene is a polymer and describe one key difference between synthetic polymers and biopolymers in terms of their origin and their breakdown in the environment.

> OCR A-Level Chemistry B: Salters (H433) — PL Polymers and life · Explain · 5 marks

> Polythene is used to make plastic bags and food wrapping. Starch is a natural polymer found in plants such as potatoes and wheat.

## Mark scheme (5 marks)

1. A polymer is a large molecule made from many small repeating units (monomers) joined together
2. Polythene is described as a polymer because it consists of many ethene monomers joined together / it has a long repeating chain structure
3. Synthetic polymers are made from crude oil / non-renewable petrochemical sources, whereas biopolymers come from living organisms / natural / renewable sources
4. Synthetic polymers such as polythene are non-biodegradable / do not break down in the environment
5. Biopolymers such as starch are biodegradable / can be broken down by microorganisms in the environment

## Key terms

- [polymer](https://www.gradenine.co.uk/glossary/polymer)
- [synthetic polymer](https://www.gradenine.co.uk/glossary/synthetic-polymer)
- [biopolymer](https://www.gradenine.co.uk/glossary/biopolymer)

## Related

- [Revision notes for OCR A-Level Chemistry B: Salters (H433)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-scientist-is-developing-new-packaging-f5172c37) · Published by Druglandscape Ltd.