Explain how a deep-sea hydrothermal vent bacterium is adapted to survive in its extreme environment.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Hydrothermal vents on the ocean floor release water at temperatures exceeding 100 °C and under very high pressure. Bacteria living at these vents are described as extremophiles.
Model answer (4 marks)
The bacterium has enzymes that are stable and active at temperatures above 100 °C, allowing its metabolic reactions to proceed efficiently in the hot vent environment.
These high‑temperature enzymes prevent denaturation and maintain catalytic activity where most proteins would unfold.
Because the vent emits no light, the bacterium does not rely on photosynthesis; instead it uses chemosynthesis, deriving energy from chemical reactions involving hydrogen sulphide or methane.
These adaptations give the bacterium a competitive advantage, enabling it to survive and thrive where most other organisms cannot.
These high‑temperature enzymes prevent denaturation and maintain catalytic activity where most proteins would unfold.
Because the vent emits no light, the bacterium does not rely on photosynthesis; instead it uses chemosynthesis, deriving energy from chemical reactions involving hydrogen sulphide or methane.
These adaptations give the bacterium a competitive advantage, enabling it to survive and thrive where most other organisms cannot.
Examiner tips
- Use the word "adapted" and link each point to the extreme conditions; show cause‑effect (enzyme stability → metabolic activity).
- Mention chemosynthesis explicitly to show understanding of energy source.
- Keep answer concise – 4 points, one sentence each.
Common mistakes
- Confusing photosynthesis with chemosynthesis; writing that the bacterium uses light.
- Failing to mention enzyme stability or high‑temperature activity.
Mark scheme (4 marks)
- The bacterium has enzymes that work at very high temperatures
- This allows metabolic reactions / chemical reactions to continue at high temperatures
- The bacterium can survive without light / does not rely on photosynthesis for energy
- These adaptations increase the bacterium's chance of survival in an environment where most organisms cannot live
Related
- Revision notes: Adaptations, interdependence and competition →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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