EESA01H3 Chapter Notes - Chapter 5: Dynamic Equilibrium, Water Cycle, Emergence

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31 Oct 2010
-A system is a network of relationships among parts, elements or components that interact
with and influence one another through the xchange of energy, matter or info.
-systems receive inputs of energy, matter or info and process them.
-open systems (open to both energy and matter - will take in energy(sunlight) and also
matter (water, carbon, oil, gas..etc) and also output the product of rxn of the inputs)
everything can be systems- e.g. this classroom, mouse
-closed system are those that receive inputs and produce outputs of energy but not matter.
(only opened to energy, not matter)the Earth is a closed system. the matter gets recycled and
eventually creates heat, Earth engulfs a lot of opened systems.
- matter cycles among system but does not leave or enter. but in nature there is no system
thats truly closed.
-feedback loop - a systems output can serve as an input to the same system. (e.g. earth has
its own feedback loops - not going to 3000 degrees.)
-negative feedback loop (enhence stability) results when the output of a system becomes the
input of the system thus moving the system in the opposite direction. inputs and outputs
essentially neutralize one anothers effects, stabilizing the system.
-positive feedback loop (destabilizing effect) rather than stabilizing a system, it drives it
further towards 1 extreme or another. E.g. population growth (more ppl born = more ppl to
give birth = more...etc). Rare in nature but common in natural systems altered by human
-dynamic equilibrium is when processes w/in a system move in opposite dir’n @
equivalent rates so their effects balance out. it’s an ever-changing balance not statistic
- homeostasis is the tendency of a system to maintain constant or stable internal conditions.
(in stable, steady state)
- emergent properties are characteristics thats not evident in the components alone.
-The earth can be broken down into a few sub-systems. such as the atmosphere-(air
surrounding our planet) everything above Earth’s surface. Lithosphere-(rock and sediment
beneath our feet, in the planet’s uppermost layers) everything below the surface, rocks...etc.
Biosphere-consists of all the living things and the non living portions which they interact
with. Hydrosphere-all the water based systems on earth (oceans, lakes rivers, ponds...etc)
All these systems’ boundaries overlap.
-Earth itself is a closed system, and these are all the opened systems w/in earth that interact
w/each other. Everything happens in the closed boundary of Earth itself.
-Over time, Rocks and minerals (naturally occurring, inorganic crystalline solids) are
heated, melted, cooled broken down and reassembled in a very slow process called the rock
cycle. (help determine biotic components of region’s ecosystem)
-All rocks can melt if T is high enough, liquid state of rock = magma, it amy flow or spatter
across Earth’s surface as lava. Cooled magma forms igneous rock.
-magma that cools slowly and solidifies under Earth’s surface is known as intrusive or
plutonic rock. (e.g. granite)
-magma from a volcano solidifies on the surface cools very quickly so minerals have little
time to grow into coarser crystals -> extrusive or volcanic rock. (e.g. basalt)
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-sediments are formed when overtime the wind/water strips off tiny grains of rock and the
particles are blown or washed downstream from their sources. The remains are usually
deposited very slowly but floods accelerate the process. Sediment layers accumulate over
time > weight and pressure of layers ^. Sedimentary rocks (tell by layers) are formed when
minerals are seeped through the sediment layers acting as a kind of glue, binding the
sediment particles together. this way of rock formation is known as lithification
(compaction, cementation, and crystallization). (e.g. limestone)
-when intense heat+pressure is exerted on rock, it becomes a metamorphic rock - crystals
reshaped .’. changing its appearance and physical properties. (e.g. marble)
-any of these types of rocks can become one another.
-Crust - a lightweight layer on the surface of earth. Under the crust there’s a soft malleable
layer - mantle. below the mantle is a liquid layer- outer core. in the center is a heavy solid
molten heavy core mostly made of iron.
-Earth’s internal heat drives convection currents in loops in mantle, upward as it warms,
downward as it cools. as the mantle material moves around, it drags large plates of crust
along its surface edge.
-Earth consists of around 15 major plate tectonics and they all move around (mantle).
-at divergent plate boundaries magma rise upward and divide the plates by pushing them
-at transform plate boundary 2 plates slide alongside each other creating friction that leads
to earthquakes.
-at a convergent plate boundaries one plate may be subducted beneath another leading to
volcanism, or both plates may be uplifted, causing mountain ranges to form.
-an ecosystem involves all organisms and non living entities that occur and interact in a
particular area at the same time.
-ecosystems are systems that receive inputs of energy, process and transform that energy
while cycling matter internally, and produce a variety of outputs that can move into other
-matter is generally recycled b/c when an organism dies, its nutrients remain in the system.
-Energy of sunlight drives photosynthesis in producers -> the transfer of chemical energy
among trophic levels. some energy exit the system as heat
-matter and nutrients move among trophic levels .
-biomass - biological material; comprises living and recently deceased organic matter
-gross primary production is the energy that results when autotrophs convert solar energy
to energy of chemical bonds in sugars through photosynthesis. autotrophs use a portion of
this production to power their own metabolism by respiration. The energy that remains after
respiration, which is used to generate biomass, is called net primary production (gross
primary production - respiration)
-the total biomass heterotrophs generate by consuming autotrophs = secondary production
-Net ecosystem production: NPP - heterotrophic respiration
-the rate at which production occurs is termed productivity, net primary productivity is
when plants can rapidly convert solar energy to biomass.
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