Adaptations

This lesson covers adaptations — the features that help organisms survive in their environment — as required by the Edexcel GCSE Combined Science specification (1SC0). You need to understand the three types of adaptation (structural, behavioural and functional), explain how adaptations arise through natural selection, and describe how extremophiles survive in extreme environments.

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What Is an Adaptation?

An adaptation is a feature or characteristic that has evolved in an organism, making it better suited to its environment. Adaptations increase an organism's chance of survival and reproduction.

Adaptations arise through natural selection: organisms with beneficial features are more likely to survive, reproduce and pass on the genes for those features to the next generation.

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Three Types of Adaptation

Type	Definition	Examples
Structural	Physical features of the body	Thick fur for insulation; thorns on plants; streamlined body shape
Behavioural	Actions an organism takes to survive	Migration, hibernation, courtship displays, nocturnal activity
Functional	Internal processes that help survival	Production of venom; antibiotic resistance in bacteria; desert plants closing stomata during the day

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Structural Adaptations

Animals

Adaptation	Organism	How it helps
Thick blubber layer	Polar bear, whale	Insulation to reduce heat loss in cold environments
White fur / camouflage	Arctic fox, polar bear	Blends with snow; avoids predators or helps ambush prey
Large ears	Fennec fox (desert)	Large surface area increases heat loss, helping to cool the body
Long, sharp claws	Eagle, lion	Catching and holding prey
Streamlined body	Dolphin, shark	Reduces drag in water, allowing faster swimming

Plants

Adaptation	Organism	How it helps
Thorns / spines	Cactus, rose	Deters herbivores from eating the plant
Deep or widespread roots	Desert plants	Reach water deep underground or over a wide area
Thick, waxy cuticle	Desert and evergreen plants	Reduces water loss by evaporation
Large, thin leaves	Rainforest plants	Maximise light absorption for photosynthesis
Small, curled leaves or needles	Marram grass, conifers	Reduce surface area for water loss

Exam Tip: When describing an adaptation, always link the feature to a specific survival advantage (e.g. "thick fur reduces heat loss, allowing the animal to maintain body temperature in cold environments").

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Behavioural Adaptations

Adaptation	Organism	How it helps
Migration	Swallows, wildebeest	Move to areas with more food or better breeding conditions
Hibernation	Hedgehog, dormouse	Reduces energy needs during winter when food is scarce
Nocturnal activity	Owl, bat	Avoids daytime predators; reduces water loss in hot habitats
Courtship displays	Peacock, bower bird	Attracts a mate, increasing reproductive success
Playing dead	Opossum	Deters predators that prefer live prey

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Functional (Physiological) Adaptations

Adaptation	Organism	How it helps
Production of venom	Snake, spider	Immobilises prey or deters predators
Production of poison	Poison dart frog	Deters predators from eating the organism
Antibiotic resistance	MRSA bacteria	Survives exposure to antibiotics; can continue to reproduce
Closing stomata during the day	Desert plants (e.g. cacti)	Reduces water loss by transpiration in hot conditions
Production of antifreeze proteins	Arctic fish	Prevents ice crystals forming in blood, allowing survival in sub-zero water

Exam Tip: Functional adaptations are harder to see because they involve internal processes. If the exam mentions "biochemical" or "physiological" adaptations, think about internal chemistry.

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Extremophiles

Extremophiles are organisms that live in environments that are extreme compared to what most life can tolerate. They are often microorganisms (bacteria or archaea).

Extreme Environment	Example Organism	Adaptation
Very hot (e.g. hot springs, deep-sea vents)	Thermophilic bacteria	Heat-stable enzymes that do not denature at high temperatures
Very cold (e.g. Antarctic ice)	Psychrophilic bacteria, Antarctic fish	Antifreeze proteins; flexible cell membranes
Very salty (e.g. salt lakes)	Halophilic archaea	Specialised proteins and ion pumps to prevent water loss
Very acidic (e.g. acid mine drainage)	Acidophilic bacteria	Cell membranes and enzymes resistant to low pH
Very high pressure (e.g. deep ocean)	Barophilic bacteria	Proteins that function under extreme pressure

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Competition for Resources

Adaptations help organisms compete for limited resources. The better adapted an organism is, the more likely it is to obtain resources and survive.

graph TD
    A["Limited Resources"] --> B["Competition"]
    B --> C["Better-adapted organisms survive"]
    B --> D["Poorly-adapted organisms struggle"]
    C --> E["Reproduce and pass on advantageous genes"]
    D --> F["May die or fail to reproduce"]
    E --> G["Adaptation becomes more common in population"]

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Natural Selection and Adaptations

Adaptations do not appear because an organism "needs" them. They arise through natural selection:

1. Individuals within a population show variation in their characteristics (due to genetic differences)
2. Those with features better suited to the environment are more likely to survive and reproduce
3. They pass on the genes for these advantageous features to their offspring
4. Over many generations, the beneficial trait becomes more common in the population

Exam Tip: Never say an organism "chooses" to adapt or "develops" an adaptation during its lifetime. Adaptations arise over many generations through natural selection acting on genetic variation.

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Summary