Explain why micro-organisms are used to produce medicines such as penicillin and insulin on a large scale, rather than obtaining these substances from other sources.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Micro‑organisms reproduce very rapidly, giving large numbers of cells in a short time.
Because of this, a small inoculum can be grown to produce huge quantities of the desired product quickly.
They can be cultivated in fermenters or bioreactors that use inexpensive nutrients and growth media, making the process cost‑effective.
Obtaining the same amounts from the natural source would be difficult, unethical or impractical – for example, insulin would have to be extracted from thousands of animal pancreases, and penicillin cannot be harvested in sufficient quantity from the fungus without fermentation.
Because of this, a small inoculum can be grown to produce huge quantities of the desired product quickly.
They can be cultivated in fermenters or bioreactors that use inexpensive nutrients and growth media, making the process cost‑effective.
Obtaining the same amounts from the natural source would be difficult, unethical or impractical – for example, insulin would have to be extracted from thousands of animal pancreases, and penicillin cannot be harvested in sufficient quantity from the fungus without fermentation.
Examiner tips
- Show the link between rapid growth and large‑scale production. Mention cheap growth media and fermenters. Explain why natural sources are limited or unethical.
- Use the exact terms "fermenter", "bioreactor", "short generation time".
Mark scheme (4 marks)
- Micro-organisms reproduce rapidly / have a short generation time
- Large quantities of the medicine/product can be produced in a relatively short time
- Micro-organisms can be grown in fermenters/bioreactors using cheap nutrients/growth media
- It would be difficult, unethical, or impractical to obtain sufficient quantities from the original source (e.g. extracting insulin from animal pancreases is limited / penicillin cannot be harvested in large enough amounts without the fungus)
Key terms in this question
micro-organisms · penicillin · insulin · large scale
Related
- All WJEC GCSE Biology (Wales) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →