Explain why the majority of plastics used in everyday products are difficult to dispose of responsibly, and describe one way in which scientists have tried to address this problem.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Billions of tonnes of plastic waste are generated globally each year. Most of this waste ends up in landfill or the natural environment, where it persists for hundreds of years. Chemists are working to develop alternatives that reduce this environmental burden.
Model answer (5 marks)
1. Most everyday plastics are made from synthetic polymers.
2. The long polymer chains are not broken down by microorganisms.
3. Consequently the plastics are non‑biodegradable.
4. They therefore persist and accumulate in the environment for very long periods.
5. Scientists have produced biodegradable polymers, e.g. starch‑based plastics, which microorganisms can degrade, reducing landfill waste and environmental impact.
2. The long polymer chains are not broken down by microorganisms.
3. Consequently the plastics are non‑biodegradable.
4. They therefore persist and accumulate in the environment for very long periods.
5. Scientists have produced biodegradable polymers, e.g. starch‑based plastics, which microorganisms can degrade, reducing landfill waste and environmental impact.
Examiner tips
- Use the exact terms ‘synthetic polymers’, ‘non‑biodegradable’, ‘persist’, ‘biodegradable polymers’, and mention a specific example such as starch or cornstarch.
- Show the causal chain: polymer → non‑biodegradable → persistence → problem, then solution → biodegradable polymer → reduced impact.
- Keep each point concise and separate with numbers or bullets.
Common mistakes
- Confusing biodegradable with recyclable plastics.
- Using vague words like ‘natural’ instead of ‘biodegradable’.
- Failing to name a specific biodegradable polymer such as starch‑based plastic.
Mark scheme (5 marks)
- Most plastics are made from synthetic polymers
- The polymer chains are not broken down by microorganisms (non-biodegradable)
- This means they persist / accumulate in the environment for a very long time
- Scientists have developed biodegradable polymers (e.g. made from plant starch / cornstarch) that can be broken down by microorganisms
- This reduces the amount of plastic that accumulates / reduces environmental impact / reduces landfill waste
Related
- All OCR A-Level Chemistry B: Salters (H433) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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