Explain why it is important to carry out fermentation in a bioreactor under carefully controlled conditions when producing a useful product such as an antibiotic from micro-organisms.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
1. Temperature must be kept at the optimum for the micro‑organism so that its metabolism and growth are maximised.
2. Maintaining the optimum temperature keeps the enzymes in the cells active and working efficiently, which is essential for product synthesis.
3. The pH must be controlled and kept at the optimum value, because enzyme activity and cell growth are pH‑dependent.
4. Aseptic or sterile conditions must be maintained to prevent contamination by unwanted micro‑organisms, which could out‑compete the product‑producing strain or degrade the product.
2. Maintaining the optimum temperature keeps the enzymes in the cells active and working efficiently, which is essential for product synthesis.
3. The pH must be controlled and kept at the optimum value, because enzyme activity and cell growth are pH‑dependent.
4. Aseptic or sterile conditions must be maintained to prevent contamination by unwanted micro‑organisms, which could out‑compete the product‑producing strain or degrade the product.
Examiner tips
- Use the exact wording from the mark scheme – e.g. ‘temperature must be controlled’, ‘pH must be controlled’, ‘aseptic conditions’. Show the logical link: controlled conditions keep enzymes active and prevent contamination, which is why they are essential for antibiotic production.
Common mistakes
- Writing ‘high temperature’ or ‘low temperature’ instead of ‘optimum temperature’. Forgetting to mention pH or aseptic conditions. Using vague phrases like ‘good conditions’ without specifying temperature, pH or sterility.
Mark scheme (4 marks)
- Temperature must be controlled / kept at optimum
- To maintain optimum enzyme activity in the micro-organisms / so enzymes work efficiently
- pH must be controlled / kept at optimum
- Aseptic / sterile conditions must be maintained to prevent contamination by unwanted micro-organisms
Key terms in this question
Related
- All WJEC GCSE Biology (Wales) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →