18.2) Adaptive features

18.2) Adaptive features


Adaptive feature: is an inherited feature that helps an organism to survive and reproduce in it environment.

Adaptive features: is the inherited functional features of an organism that increase its fitness.

Fitness: is the probability of that organism surviving and reproducing in the environment in which it is found.


Adaptations to arid conditions:

  • In both hot and cold climates plants may suffer from water shortage.
  • High temperatures accelerate evaporation from leaves.
  • At very low temperatures the soil water becomes frozen and therefore unavailable to the roots of plants.
  • Plants modified to cope with lack of water are called xerophytes.
  • Loss of leaves removes virtually all evaporating surfaces at a time when water may become unavailable.
  • Pine tree, Cacti and Marram grass.


Adaptations to living in water:

  • Plants adapted to living in water are called hydrophytes.
  • Water lily.
  • The leaves contain large air spaces to make them buoyant, so they float on or near the surface.
  • This enables them to gain light for photosynthesis.
  • The lower epidermis lacks stomata to prevent water entering the air spaces, while stomata are present on the upper epidermis for gas exchange.
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