B15.6 Adapt and Survive

A free GCSE Combined Science: Trilogy lesson for AQA (8464) from OBA School: structural, behavioural and functional adaptations, extreme environments 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 extreme 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, sharp teeth, colour patterns.
• Behavioural: An adaptation in the way an organism acts, e.g. migrating, huddling, using tools, rolling into a ball.
• Functional: An adaptation in how body processes work, e.g. making venom, producing very concentrated urine.
• Mimicry: A harmless species looking like a harmful one, so predators avoid it.
• 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. Well-adapted organisms outcompete others of their own species and of other species.

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.

Exam tip: Always describe an adaptation together with the advantage it gives. “Thick fur” is just a fact; “thick fur traps air, which insulates, so less heat is lost” is an adaptation.

Three types of adaptation

• structural; Meaning body shape or features; Examples an eagle’s sharp eyesight and hooked beak; a hoverfly’s wasp-like stripes (mimicry); a cactus’s spines
• behavioural; Meaning what the organism does; Examples swallows migrate south in autumn; musk oxen form a tight circle in blizzards; some birds use twigs as tools to reach insects
• functional; Meaning processes inside the body; Examples snakes and spiders make venom; foxglove leaves make poisons that deter grazers; Antarctic fish make antifreeze proteins; plant hormones make shoots grow towards light

Worked example: classifying adaptations

A camel has (1) wide, flat feet, (2) rests in the shade at midday, (3) lets its body temperature rise 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

Extreme environments and extremophiles

An extreme environment is one where most organisms could not survive: very hot or cold, very acidic or salty, very high pressure, or with almost no water or oxygen. Organisms that live there, mostly microorganisms (bacteria and archaea), are called extremophiles.

• very high temperature; Where hot springs, deep-sea hydrothermal vents; 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 the deep ocean floor; Adaptation proteins and membranes that work under huge pressure
• very low temperature; Where polar ice and seas; 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 stopped by about 55 °C because its active site has been denatured.
The hot-spring bacterium’s enzyme has an optimum of about 80 °C and is only denatured above about 95 °C.

Answer: optimum ≈ 37 °C vs ≈ 80 °C

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 or reproduce.
• Thinking all food chains start with photosynthesis. At deep-sea vents bacteria use chemicals instead.

Revision questions

Try these, then check your answers below each one.

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

Answer: An organism that lives in extreme conditions

Working: Extremophiles live in very high temperatures, pressures or salt concentrations, e.g. bacteria in hot springs.

Question 2. Which of these is a behavioural adaptation? (Choose from: A gerbil stays in its burrow during the hottest part of the day, A polar bear has a thick layer of fat, A camel produces very concentrated urine, A cactus has spines.)

Answer: A gerbil stays in its burrow during the hottest part of the day

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

Question 3. The diagram shows a deep-sea hydrothermal vent. No light reaches it, yet many animals live there. What is at the start of the food chain? (Choose from: Bacteria that get energy from chemicals, such as hydrogen sulfide, in the vent water, Green plants that photosynthesise in the dark, Algae floating down from the sunlit surface only, Tube worms that make glucose by photosynthesis.)

Answer: Bacteria that get energy from chemicals, such as hydrogen sulfide, in the vent water

Working: Extremophile bacteria use chemicals from the vent as their energy source to make food. Tube worms and other animals depend on these bacteria.

Related lessons

• Previous lesson: B15.5 Competition in Plants
• Next lesson: B15.7 Adaptation in Animals
• In this chapter: B15.1 The Importance of Communities
• In this chapter: B15.2 Organisms in Their Environment
• In this chapter: B15.3 Distribution and Abundance

Continue in the full course

This lesson is section B15.6 (AGCSC1506) of our free GCSE Combined Science 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 Combined Science course.