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.