Adaptations in organisms for IB biology Evolution unit.

Grasses and Sand Dunes (Why)

Sand retains water after rainfall, Tolerance of high salt concentrations, sand accumulation

Grasses in sand dunes (adaptations)

Lyme grass - Thick, waxy, cuticle on leaves for reduced transpiration. Stomata is indented to hold humid air. Leaves roll up during droughts to reduce surface area to wind. Tough Schlerenchyma - prevents wilting. Rhizomes grow upwards as sand accumulates and extend deep into the sand to obtain water. Carbs accumulate in root and leaf cells to increase osmotic potential.

Mangrove swamps (why)

sheltered conditions with accumulating mud, flooded seawater at high tides. Waterlogged anaerobic soils, high salt concentrations

Adaptations for Red mangrove

Secretion of excess salt from salt glands in the leaves. Root epidermis coated in cork to reduce permeability to salt and excessive absorption. Cable roots near soil surface because there’s more oxygen there. Pneumatophores grow up in the air to absorb oxygen. Stilt roots grow out in downward arc to support the tree. Large buoyant seed that can be carried by the ocean. Accumulation of mineral ions - increase osmotic potential.

Swimming adaptations

Stream lining, Widest near front, tapers towards the rear. Flippers, flukes, dorsal fins. Smooth body surface and even blubber distribution. No hair

Swimming - locomotion adaptations

Flippers for steering. Flukes on tail to increase thrust. Dorsal fin for stability. Blubber for buoyancy.

Swimming - Ventilation

Blowhole - allows breathing. No connection between mouth and lungs so water doesn’t get in.

Hot desert challenges.

High day temperatures, but cold nights. Very low rainfall and limited soil.

Saguaro Cactus (adaptations)

Wide and deep root system to collect more water. Pleated stems for shrinkage and droughts and swelling after it rains. Vertical stem orientation - reduce daytime sunlight and take advantage of cool nights. Waxy cuticle - reduce transpiration. Spine leaves - reduce surface area for transpiration and preventing animals from feeding on it.

Fennec fox.

Nocturnal - avoids high temperatures. Underground den - stays cool during the day. Thick hair - heat insulation. Hair covering feet pads - insulation for walking on hot sand. Pale coat - reflects sunlight. Large ears - radiate heat and keep body temperature down.

Tropical rainforests

High temperatures, High precipitation, High light intensity

Yellow Meranti

Grows very tall - avoids competition for light. Thick trunk and dense wood - support against wind stress. Smooth trunk - shed rainwater. Enzymes adapted to tolerate high temperatures. High quantities of flower and seed produced once every 5 years - deter species that eat seeds.