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The Environment. The Environment. This is made up of all the biotic (living) and abiotic (non-living) factors which affect the lives of organisms. Abiotic Factors. These are the non-living factors in the environment. Light Gravity Temperature Water Current Chemicals Touch Sound
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The Environment • This is made up of all the biotic (living) and abiotic (non-living) factors which affect the lives of organisms.
Abiotic Factors • These are the non-living factors in the environment. • Light • Gravity • Temperature • Water • Current • Chemicals • Touch • Sound • Pressure • Wind • Substrate • Fire
Tolerance • The environmental factors that can affect an organism, be they biotic or abiotic, do not remain constant. • Abiotic factors such as temperature, wind and humidity can vary from day to day and from season to season. • Other factors may change more slowly • E.g. levels of predation and food supply.
Tolerance • An organism that is living successfully in an area must be able to Tolerateany such changes. • If it could not, it would have either died out or moved to a more suitable place. • An organisms ability to survive variation in environmental conditions is called Tolerance. • Tolerance varies between species.
Examples • Trout eggs will develop at temperatures between 0ºC and 12ºC, while frogs’ eggs will tolerate a 0ºC to 30ºC range.
Tolerance • Tolerance varies within species as well. • E.g. Human tolerance to temperature. In winter some students appear to keep warm with only a cotton blouse, while others feel cold even with a jersey.
Acclimation • It is possible for the tolerance or an organism to change, if, the conditions change slowly. • This is called Acclimation. • All organisms become acclimated to the seasons. • Dogs, cattle and many other mammals grow a thicker coat of fur as winter approaches and cast it off with the onset of the following warm season.
Acclimation • Many species of mammals and birds increase their tolerance of the cold by accumulating a fat layer beneath the skin which improves heat insulation.
Picture This……… • You have 2 fish tanks, A and B Tank A Tank B
Picture This • Everyday for a month or 2 you put a pinch of salt into Tank B, so it very gradually gets saltier. • If you then shifted a fish from Tank B into the fresh water of Tank A, it would die. • This is because the fish in Tank B have become acclimated to the saltier water – as it was done slowly.
Try This. • Explain why athletes train at high altitudes?
Answer. • At high altitudes, body would increase the production of red blood cells. • If training at gradually higher altitudes over a training season, the athlete would have a larger number of red blood cells than the athlete who trained at sea level.
Biotic Factors • These can be: • Intraspecific (between members of the same species) • Interspecific (between members of different species) • WS – Inter and Intraspecific Competition