16.6 Adapt and Survive

A free GCSE Biology lesson for AQA (8461) from OBA School: structural, behavioural and functional adaptations, and extremophiles. Watch the video, read the explanation and worked examples, then try the revision questions. You can work through the full lesson, with every video, practice quizzes and printable worksheets with mark schemes, in our free online course.

What you will learn

• Explain what an adaptation is and why organisms have them
• Classify adaptations as structural, behavioural or functional
• Describe what extremophiles are and the conditions they live in
• Explain how adaptations help organisms survive, using data

Key words

• Adaptation: A feature that helps an organism survive and reproduce in the conditions where it normally lives.
• Structural: An adaptation of the body’s shape or parts, e.g. thick fur, spines, webbed feet.
• Behavioural: An adaptation in the way an organism acts, e.g. migrating, hibernating, being active at night.
• Functional: An adaptation in how body processes work (metabolism, chemistry), e.g. making very concentrated urine.
• Extremophile: An organism that lives in extreme conditions, such as very high temperature, pressure or salt concentration.

What is an adaptation?

Every habitat makes demands on the organisms living there: it may be cold, dry, dark, salty or full of predators. Organisms have adaptations that let them survive in the conditions where they normally live.

Adaptations come about by natural selection over many generations. Individuals with features that suit the environment are more likely to survive, breed and pass on the alleles for those features.

Key fact: An adaptation is not something an organism decides to grow. It is inherited, and has been selected over many generations.

Three types of adaptation

• structural; Meaning body shape or features; Examples polar bear’s thick fur and white colour; cactus spines; long eyelashes of a camel to keep sand out
• behavioural; Meaning what the organism does; Examples swallows migrate south in autumn; hedgehogs hibernate; desert animals stay in burrows by day
• functional; Meaning processes inside the body; Examples desert rodents make very concentrated urine; some Antarctic fish make antifreeze proteins; seals slow their heart rate when diving

Worked example: classifying adaptations

A camel has (1) wide feet, (2) rests in the shade at midday, (3) can let its body temperature rise by several degrees during the day so it sweats less.
(1) is a body feature → structural. (2) is something it does → behavioural. (3) is a change in a body process → functional.

Answer: structural, behavioural, functional

Exam tip: Name the adaptation, then explain how it helps the organism survive or reproduce: “thick fur traps air, which insulates, so less heat is lost”.

Extremophiles

Some organisms, mostly microorganisms (bacteria and archaea), live where most life would die. They are called extremophiles.

• very high temperature; Where hot springs, deep-sea hydrothermal vents (above 80 °C); Adaptation enzymes and proteins that do not denature at high temperature
• very high salt concentration; Where salt lakes, salt pans; Adaptation cells that do not lose water by osmosis in very salty water
• very high pressure; Where deep ocean trenches; Adaptation proteins and membranes that work under huge pressure
• very low temperature; Where polar ice, frozen soil; Adaptation enzymes that work at low temperatures; antifreeze substances

Worked example: reading the graph

The soil bacterium’s enzyme works best at about 37 °C and has almost stopped working by 60 °C because its active site has been denatured.
The hot-spring bacterium’s enzyme has an optimum of about 80 °C. Its active site keeps its shape at temperatures that would denature most enzymes; it is only denatured above about 85–90 °C.

Answer: optimum ≈ 37 °C vs ≈ 80 °C

Enzymes from extremophiles are useful to people, for example in biological washing powders and in copying DNA in the laboratory, which uses very high temperatures.

Common mistakes

• Saying an organism “adapts” to a new place during its lifetime. Adaptations are inherited and evolve over many generations.
• Mixing up behavioural and functional. If you could film it, it is usually behavioural; if it happens inside the body, it is functional.
• Naming an adaptation without explaining how it helps the organism survive.
• Thinking extremophiles are only bacteria. Most are microorganisms, but some animals (e.g. tube worms near vents) live in extreme places too.

Revision questions

Try these, then check your answers below each one.

Question 1. What is an extremophile? (Choose from: An organism that lives in very extreme conditions, An organism that has become extinct, A predator at the top of a food chain, A plant that grows only in deserts.)

Answer: An organism that lives in very extreme conditions

Working: Extremophiles, mostly microorganisms, live in extreme conditions such as very high temperature, pressure or salt concentration.

Question 2. True or false? All bacteria have enzymes that are denatured above about 45 °C.

Answer: False

Working: False. Bacteria from hot springs and deep-sea vents have enzymes that work at 80 °C or more without being denatured.

Question 3. Which of these is a behavioural adaptation? (Choose from: A desert fox stays in its burrow during the day, A polar bear has thick fur, A camel produces very concentrated urine, A cactus has spines.)

Answer: A desert fox stays in its burrow during the day

Working: Staying in a cool burrow by day is behaviour. Fur and spines are structural; concentrated urine is functional.

Related lessons

• Previous lesson: 16.5 Competition in Plants
• Next lesson: 16.7 Adaptation in Animals
• In this chapter: 16.1 The Importance of Communities
• In this chapter: 16.2 Organisms in Their Environment
• In this chapter: 16.3 Distribution and Abundance

Continue in the full course

This lesson is section 16.6 (AGCBH1606) of our free GCSE Biology course for AQA. In the full course you get every video for this section, a self-marking practice quiz, a printable worksheet with a mark scheme, chapter tests, and your progress saved. Go to the full GCSE Biology course.