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.