Revision Notes

18.3 Adaptive Features


  • An adaptive feature is an inherited feature that helps an organism to survive and reproduce in its environment
  • You should be able to interpret images or other information about a species in order to describe its adaptive features, for example:


Adaptive features 1, CIE IGCSE Biology

A typical question here might be to explain how the leaf area and distribution and density of stomata help different species of plant survive in their different habitats

Extended Only

Adaptations & Fitness

  • Adaptive features are the inherited functional features of an organism that increase its fitness
  • Fitness is the probability of an organism surviving and reproducing in the environment in which it is found
Extended Only

Hydrophytes & Xerophytes


  • Plants adapted to live in extremely wet conditions
  • Common adaptations include:
    • Large air spaces in their leaves to keep them close to the surface of the water where there is more light for photosynthesis
    • Small roots as they can also extract nutrients from the surrounding water through their tissues
    • Stomata usually open all the time and mainly found on the upper epidermis of the leaf where they can exchange gases much more easily with the air


Hydrophyte adaptations, IGCSE & GCSE Biology revision notesHydrophytes are adapted to live in wet conditions such as ponds



  • Plant adapted to live in extremely dry conditions
  • Common adaptations include:
    • Thick waxy cuticle – the cuticle cuts down water loss in two ways: it acts as a barrier to evaporation and also the shiny surface reflects heat and so lowers temperature
    • Sunken stomata: stomata may be sunk in pits in the epidermis; moist air trapped here lengthens the diffusion pathway and reduces evaporation rate
    • Leaf rolled with stomata inside and an inner surface covered in hairs – traps moist air and prevents air movement across stomata which reduces transpiration
    • Small leaves: many xerophytic plants have small, needle-shaped leaves which reduce the surface area and therefore the evaporating surface
    • Extensive shallow roots allowing for the quick absorption of large quantities of water when it rains
    • Thickened leaves or stems which contain cells that store water


Xerophyte adaptations, IGCSE & GCSE Biology revision notesXerophytes are adapted to live in extremely dry conditions such as deserts

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