AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Adaptations: Bacteria living in deep sea vents are extremophiles.
Extremophiles are organisms adapted to survive and reproduce in environments where conditions are extreme, such as very high temperature, pressure, salt concentration or acidity.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 6 of 6
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Extremophiles are organisms adapted to survive and reproduce in environments where conditions are extreme, such as very high temperature, pressure, salt concentration or acidity. Deep sea vents release superheated water rich in dissolved minerals, so bacteria living there must keep their enzymes and cell structures working despite temperatures that would denature enzymes in most organisms. Their enzymes often have unusually stable shapes, and their cell membranes resist heat and pressure. This makes them adapted to that specific niche, where they may obtain energy by chemosynthesis rather than photosynthesis. The statement is a specific example of a broader principle: every organism is adapted to its environment, and extreme environments select for extreme adaptations.
What earns the marks
- Extremophiles are organisms adapted to live in extreme environments, for example very high temperature, high pressure, high salt concentration or extreme pH.
- Deep sea vents release very hot water and dissolved minerals, creating conditions that would denature enzymes in most organisms.
- Bacteria living in deep sea vents have enzymes and cell structures that remain functional at high temperature and pressure.
- The example illustrates the general principle that organisms are adapted to the conditions of their environment.
Common mistakes and how to put them right
Thinking extremophiles are a separate kingdom or type of organism.
Put it right: Extremophile is a description of an organism's habitat and adaptations, and many are bacteria or archaea.
Assuming deep sea vent bacteria photosynthesise.
Put it right: Light does not penetrate to these vents, so they commonly use chemosynthesis.
Believing extremophile enzymes are unaffected by temperature.
Put it right: Their enzymes are adapted to work at high temperature, but they still have an optimum and can be denatured if conditions change too far.
Exam tips
- Link the example back to the definition of adaptation: a feature that increases an organism's chance of survival and reproduction in its environment.
- Use the phrase 'denature' accurately when explaining why ordinary enzymes would not work in a deep sea vent.
- If asked to suggest an adaptation, name a specific feature and explain how it helps survival in that extreme condition.
Try the lesson
The start of the Adaptations: Bacteria living in deep sea vents are extremophiles. lesson, made from checked teaching notes for this specification point.
Have a go first
What is an extremophile? Select the correct answer.
Listen
Extremophiles are organisms adapted to survive and reproduce in environments where conditions are extreme, such as very high temperature, pressure, salt concentration or acidity. Deep sea vents release superheated water rich in dissolved minerals, so bacteria living there must keep their enzymes and cell structures working despite temperatures that would denature enzymes in most organisms. Their enzymes often have unusually stable shapes, and their cell membranes resist heat and pressure. This makes them adapted to that specific niche, where they may obtain energy by chemosynthesis rather than photosynthesis. The statement is a specific example of a broader principle: every organism is adapted to its environment, and extreme environments select for extreme adaptations. A strong answer earns marks for these points. Extremophiles are organisms adapted to live in extreme environments, for example very high temperature, high pressure, high salt concentration or extreme pH. Deep sea vents release very hot water and dissolved minerals, creating conditions that would denature enzymes in most organisms. Bacteria living in deep sea vents have enzymes and cell structures that remain functional at high temperature and pressure. The example illustrates the general principle that organisms are adapted to the conditions of their environment. A common slip: Thinking extremophiles are a separate kingdom or type of organism. Instead, extremophile is a description of an organism's habitat and adaptations, and many are bacteria or archaea. Exam tip: Link the example back to the definition of adaptation: a feature that increases an organism's chance of survival and reproduction in its environment.
Key words
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Extremophiles
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Extreme conditions and enzyme stability
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Niche and survival
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Chemosynthesis in the absence of light
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See every definition
- Extremophiles
- Organisms adapted to survive and reproduce in environments where conditions are extreme, such as very high temperature, pressure, salt concentration or acidity.
- Extreme conditions and enzyme stability
- Bacteria in deep sea vents must keep their enzymes and cell structures working despite temperatures that would denature enzymes in most organisms, and their enzymes often have unusually stable shapes.
- Niche and survival
- These bacteria are adapted to that specific niche, where their cell membranes resist heat and pressure.
- Chemosynthesis in the absence of light
- Light does not penetrate to these vents, so the bacteria may obtain energy by chemosynthesis rather than photosynthesis.
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