Adaptation and competition

Every living thing competes for what it needs. The ones best suited to their environment do best.

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Adaptations

An adaptation is a feature that helps an organism survive in its environment.
Polar bear: thick white fur and a thick layer of fat for warmth; white colour for camouflage on snow.
Camel: can go a long time without drinking; wide feet that do not sink in sand; long eyelashes against sand.
Cactus: spines instead of broad leaves, so less water is lost; a thick stem that stores water; long or widespread roots to collect water.

Competition

Organisms compete for resources that are in short supply.
Animals compete for food, water, space (territory) and mates.
Plants compete for light, water, minerals and space.
The best competitors get more resources, so they are more likely to survive and reproduce.

Predators, prey and change

Populations of predators and prey affect each other. If the number of rabbits rises, foxes have more food and their numbers rise. Then more rabbits are eaten, so rabbits fall, and later the foxes fall too.
When the environment changes, for example a new disease, a new competitor or a warmer climate, organisms that are less well adapted may die out from that area.
Worked example

A rabbit population falls from 120 to 90 after a disease. By what percentage did it fall?

  1. Fall = 120 − 90 = 30
  2. Percentage = 30 ÷ 120 × 100

Answer: 25%

Key idea

Adaptations help organisms survive where they live. Animals compete for food, water, territory and mates; plants compete for light, water, minerals and space. Predator and prey numbers rise and fall together, with the predators behind.

Key words
Adaptation
A feature that helps an organism survive and reproduce in its environment, such as the large surface area of a leaf.
Water
Pure water melts at 0 °C and boils at 100 °C. Its density is 1 g/cm³. Ice is less dense than water, so it floats.

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  1. How does white fur help a polar bear?

    1. It helps camouflage it against snow
    2. It makes it swim faster
    3. It makes it warmer by absorbing light
    4. It stores water
    Show the answer

    Answer: It helps camouflage it against snow

    Camouflage helps it hunt.

  2. How do long roots help a desert plant?

    1. They catch insects
    2. They absorb more light
    3. They reach water deep underground
    4. They make seeds
    Show the answer

    Answer: They reach water deep underground

    Water is scarce near the surface.

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Sources and references

Checked by the GCSE-ready editorial team, 17 October 2026. Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.