# Topic 1 and 2

1.1.1 Outline the concept and characteristic of a system
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1st law: energy can be transferred and transformed but it can never be created nor destroyed
so all energy in living systems comes from the sun then into producers through photosynthesis, then consumers up the food wed

2nd law: with every energy transfer or transformation energy dissipates as heat so the energy available to do work decreases
which means there is always less energy at higher trophic levels
equilibrium is a sort of equalization or end point

a steady state equilibrium means constant changes in all directions maintain a constant state (no net change) which is common to most open systems in nature

static equilibrium means no change at all which does not exist

long term changes in equilibrium point do occur

equilibrium is stable (systems tend to return to the original equilibrium after disturbances)

generally maintained by negative feedback
positive feedback:
a runaway cycle
a change in a certain direction provides output that further increases that change
change leads to increasing change- it accelerates deviation

ex: albedo effect on global warming
1. temperature increases= ice caps melt
2. less ice cap surface area= less sunlight is reflected away from earth
3. more light hits dark ocean and heat is trapped
4. further temperature increase= further melting of the ice

negative feedback:
one change leads to a result that lessens the original change
self regulating method of control leading to the maintenance of a steady state equilibrium

ex. predator prey
snowshoe hare pop increases
more food for lynx= lynx pop increase
increased predation on hares= hare pop decline
less food for lynx= lynx pop declines
less predation= increase in hare population
models are:

used when we can't measure the real event

hard with the environment because there are so many interacting variables

approximations

may yield very different results from each other or actual events

there are always unanticipated possibilities including discontinuities, synergistic interactions, and chaotic events