Adaptations For Survival – Methods Of Avoiding Extremes Of Climate. Essay, Research Paper
Dormancy 1.
Plants ·
Annuals -survive cold / drought as seeds. ·
Perennials – organs
of perennation – bulbs, tubers, rhizomes.
Deciduous trees loose leaves, reducing transpiration rate. 2. Animals Small mammals and ectotherms
hibernate. Need to increase body
fat. Reduced metabolic rate. Migration eg. Many birds migrate to find
improved food sources and warmer temperatures. Depression of freezing point in cells Plants and animals in cold climates
survive by having substances within cells that depress freezing point eg
increasing solutes in cells anti freeze substances eg glycerol. Also having air
spaces within gut or inside leaves insulates and so prevents damaging effects of ice crystals formed when water
freezes. Xerophytes Plants adapted to withstand dry
conditions eg marram grass, cacti. ·
Roll leaves to reduce evaporation from stoma ·
Stoma in sunken pits ·
Hairs on underside leaves. ·
Surface area of leaves reduced – needles ·
Increased thickness of cuticle. Body size and shape Animals with large surface areas to
volume ration ( smaller animals ) loose heat more quickly than with smaller
surface area to volume ratio. Loose heat by conduction, convection and
radiation. ·
Animals in cold climates tend to be larger with smaller
extremities than those in warm climates. ·
Counter current exchange of heat through limbs prevents
excessive heat loss.