Systems and models

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Systems and models

• A way of systematically figuring out how things
  interact.

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3rd rock from the sun.

• The Earth from space

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The Earth is the only Biosphere so far

• What is a biosphere?
• The thin bit of the whole planet earth where life
  can be found
• The Atmosphere the air
• The Lithosphere the rocks
• The Hydrosphere the lakes, seas
  and oceans
• The Ecosphere the
  living bits

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The Layers of Earth
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Outline the concept and characteristics of
ecosystems.

• An ecosystem consists of the interactions between
  the living and non living.
• The living is called biotic.
• The non-living interactions are called A-biotic.
• Put the following in the correct column

Biotic Abiotic





Plants, humidity, predation, temperature,
parasitism, competition, light intensity, season,
soil pH, mutualism, animals
Biotic Abiotic





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What is a system?

• A system is an assemblage of parts and their
  relationship forming a functioning unit
• A system can be made up of living things,
  non-living things or mixes of both.
• It can be a whole variety of sizes, from cells to
  cities to biospheres.
• Big systems can be made up of many little
  systems.
• eg. organisms, organ systems, organs, tissues,
  cells, organelles

IBO Environmental Systems and Societies subject
guide. (Page 75.)
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Some examples of systems
Sydney Cityscape
A Eukaryote cell
A motorbike
Human anatomy
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To make a system diagram there are some
conventions
All systems have They are represented as
Storages (of matter or energy) Boxes
Flows (in, thru and out) Arrows
- Inputs - Arrow in to the system
- Outputs - Arrow out of the system
Boundaries --------------------------
Processes (transfers or transformations) Label on the arrows eg - Respiration
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Using the model below, draw your own systems
diagram for some of the following

• You
• A lake
• A mobile phone
• A scooter
• A cell
• A city

Inputs
flows
Storages
flows
Outputs
Taken from page 72, Environmental Systems and
Societies Course Companion Jill Rutherford -
2009 - Oxford
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Types of System

• An open system exchanges energy and matter with
  what is around it. e.g human, pond
• 2. A closed system exchanges energy but not
  matter with its surroundings e.g. Earth
• 3. A isolated system exchanges neither energy
  nor matter with its surroundings.

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Biosphere 2

• Was Biosphere 2 open, closed or isolated? Explain
  why?
• Why was NASA so interested in what went on at
  Biosphere 2?
• Have a look for Biosphere 2 what went wrong what
  do you think?

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If youre interested - Lake Vostok

• http//en.wikipedia.org/wiki/Lake_Vostok
• Is this an isolated system?
• If not why not?
• If not isolated is it closed?

Lake Vostok.
http//www.ldeo.columbia.edu/mstuding/new_vostok_
cartoon_low.gif
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The Laws of Thermodynamics

• Thermodynamics is about the flow of energy
  (Thermo heat Dynamics - movement.)
• The 1st law states
• Energy cannot be created or destroyed it can
  however change from one form to another.
• So, the total energy in a system is constant.
• Ecosystem sunlight (photosynthesis) biomass
  eaten heat

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• The 2nd law states
• Energy goes from a concentrated form to a
  dispersed form e.g. from the sun to dispersed
  heat
• Amount of energy doesnt change but the amount
  available does
• Energy holds molecules together so as there is
  less energy, there is more disorder
• This is called entropy

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A Food Chain
The arrows represent the flow of energy from
eaten to eater!
Tertiary consumer
Producer
Secondary consumer
Primary consumer
All images from clip art except Apple tree.
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Energy losses

• The apple is only able to absorb some of the
  light. (It reflects the green)
• The worm must find the apple this takes
  wiggling and changes chemical to movement energy
  and heat.
• The little bird must fly to catch the worm and
  escape the big bird ..as above.
• The big bird

(Normally 2 efficiency)
(Normally less than 10 efficiency)
(Normally more 10 efficiency)
(Normally 10 efficiency)
The total efficiency of the big bird 0.02
x0.1x0.1x0.1 0.00002
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Sooo.

• When energy passes through living things it is
  used by the organism and eventually lost to the
  environment as heat.

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The flows can be

• A Transfer is a change in position of the
  matter or energy but not a change in form (eg
  water droplets in cloud becoming rain)
• A Transformation a change in the form or state
  of the energy (eg water from the sea evaporating
  to the atmosphere change from liquid to gas)

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Transfer or transformation?

• Predator eating prey
• Rain falling and becoming a river
• Suns heat warming up a person
• In a plant sunlight joining with CO2 and water to
  become glucose

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Equilibria - balances

• Equilibrium is the tendency of a system to return
  to an original state after it gets disturbed.
• 1. Steady state
• Your body temperature get ill, recover

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Equilibria - balances

• 2. Static nothing goes in nothing comes out
  the amount of stuff in the system stays the same.
• e.g. a chair
• NB No ecosystem or living thing.

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Stable and unstable equilibria

• Stable even quite a large disturbance will
  return to the status quo.

• Unstable even a small disturbance will upset the
  balance.

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• Some stable systems resist change

• Sometimes the change is so great it moves to a
  NEW stable position

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Feedback

• Feedback is often responsible for keeping or
  upsetting balances
• There are 2 types of feedback
• Positive (ve) feedback
• Tends to destabilize equilibrium pushing a
  system to a new state.
• Negative (-ve) feedback
• Tends to stabilize systems and resist change. It
  allows self regulation.

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Cold day. You get cold

• How does your body react?
• Hairs?
• Blood vessels?

ve feedback or ve feedback?
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Hot day?
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You get hungry. Eat lots.
ve feedback or ve feedback?

• Every day. Stomach expands.needs more to fill
  it.get hungry.

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Same system 2 ideas
-ve
ve
Climate temperature remains constant
Climate temperature increases
Which is stable? What type of feedback is
this? Which is unstable? What type of feedback is
this?
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Learn these definitions!

• Negative feedback is a self regulating method of
  control leading to the maintenance of a steady
  state equilibrium it counteracts deviation.
• Eg. Predator prey relationships.
• Positive feedback leads to increasing change in a
  system it accelerates deviation.
• Eg. Population growth.

IBO Environmental Systems and Societies subject
guide (2007) Page 15
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Models

• Simplified description to show how something works

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Evaluation of models

• An aquarium
• Computer model
• Diagram
• Advantages
  Disadvantages

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or - ?

• Allow you to predict
• May not be accurate
• Politicians may hijack them
• Can change inputs and see outcome dont have
  to wait
• May be too simple
• Can be interpreted in different ways
• Results can be shown to public

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Bibliography - Images

• Slide 2 The Earth from space NASA
  -http//farm3.static.flickr.com/2084/2222523486_5e
  1894e314_b.jpg - August 30th 2010
• Slide 4 The Layers of Earth -
  http//www.solcomhouse.com/images/struct.jp -
  August 30th 2010
• Slide 7
• Human anatomy - Renarf - http//media.photobucket.
  com/image/human20body/renarf/Zygote-3D-Male-Human
  -Anatomy-Collec.jpg - August 30th 2010
• A Eukaryote cell - Chad Williams -
  http//www.williamsclass.com/SeventhScienceWork/Im
  agesCells/EukaryoticCell.jpg - August 30th 2010
• Sydney Cityscape Roger Waite -http//www.rogersw
  ebsite.com/Australia/1420-20Sydney20City20Skyl
  ine.jpg August 30th 2010
• A Motorbike Yamaha UK - http//www.yamaha-motor.
  co.uk/Images/2009-X-City-125-static-04_prv_tcm46-2
  80314.jpg August 30th 2010
• Slide 11 Lake Vostok Michael Studinger -
  http//www.ldeo.columbia.edu/mstuding/new_vostok_
  cartoon_low.gif - August 30th 2010.
• Slide 16 Apple tree Andy and Dave Hamilton
  www.selfsufficientish.com - August 30th 2010.