Adaptations for survival - Methods of avoiding extremes of climate.
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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.

Other Notes in this Category

1. Adaptations for survival - Methods of avoiding extremes of climate.
2. Cycling Systems
3. Human activities
4. Recycling of Materials
5. Variations in Nutrient Supply

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