Topic 1 Systems and models

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A way of systematically figuring out how things
interact.
rd
3
rock from the sun.
The Earth from space
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:
1. The Atmosphere – the air
2. The Lithosphere – the rocks
3. The Hydrosphere – the lakes, seas and oceans
4. The Ecosphere – the living bits
The Layers of Earth
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
Predation
temperature
parasitism
humidity
competition
light intensity
mutualism
season
soil pH
Predation, temperature, parasitism,
humidity, competition, light
intensity, season, soil pH,
mutualism,
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.)
Some examples of systems:
Sydney Cityscape
A Eukaryote cell
Human anatomy
A motorbike
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
Using the model below, draw your own systems diagram for
the following:
• A candle
• A mobile phone
• A green plant
Inputs
flows
• You
• A forest
• A Lake
• A scooter
Storages
flows
• A cell
• A city
Taken from page 72, Environmental Systems
and Societies – Course Companion – Jill
Rutherford - 2009 - Oxford
Outputs
Types of System
1. An open system – exchanges energy and matter
with what is around it.
2. An closed system – exchanges energy but not
matter with it’s surroundings.
3. A isolated system – exchanges neither energy
nor matter with its surroundings.
Find and explain examples for each type.
Look up ‘Biosphere 2’. What sort of system were
they trying to create? Draw a systems diagram for
the project. (Maybe you will need to draw one
diagram for each biome and link the biomes.)
Biosphere 2
 http://en.wikipedia.org/wiki/Biosphere_2
 http://www.biospherics.org/experimentchrono1.ht
ml
 Was Biosphere 2 open, closed or isolated? Explain
why?
 Why was NASA so interested in what went on at
Biosphere 2?
If you’re 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
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.
The 2nd law states:
- In any isolated system entropy tends to increase
spontaneously.
What does this mean?
Why is it relevant?
 The first law is easy……we call these energy changes
“transfers” or “transformations”
 A Transfer – is a change in position of the energy but
not a change in form. (eg. Rain falling from a cloud)
 A Transformation – a change in the form or state of
the energy. (eg. light energy changing to chemical
energy in photosynthesis. Or evapouration of water
from the sea to the atmosphere. )
…The 2nd Law
 Entropy – a tendency to fall apart or become more
disordered.
 Usually energy is lost from a system as heat. (this
heat is gained by another system though – see the
1st law!)
 The energy available to do work in a system gets
less.
A Food Chain
The arrows represent
the flow of energy from
eaten to eater!
Producer
*
Primary
consumer
*All images from clip art except – Apple tree.
Secondary
consumer
Tertiary
consumer
Energy losses:
 The apple is only able to absorb some of the light. (It
reflects the green) (Normally 2% efficiency)
 The worm must find the apple – this takes wiggling
and changes chemical to movement energy and
heat. (Normally less than 10% efficiency)
 The little bird must fly to catch the worm and escape
the big bird …..as above.(Normally more 10% efficiency)
 The big bird…… (Normally 10% efficiency)
The total efficiency of the big bird = 0.02 x0.1x0.1x0.1
= 0.00002%
Sooo……….
When energy passes
through living things it is
used by the organism and
eventually lost to the
environment as heat.
Equilibria - balances
 Equilibrium is the tendency of a system to return to an
original state after it gets disturbed.
1. Steady state – stuff goes into the system stuff; goes
out of the system; the amount of stuff in the system
stays the same.
2. Static – nothing goes in; nothing comes out; the
amount of stuff in the system stays the same.
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.
• Some stable systems resist change:
• Sometimes the change is so great it moves to a NEW
stable position:
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.
Same system 2 ideas:
Climate
temperature
Less heat
comes in
-ve
More reflection
of sunlight
Climate
temperature
Increased
temperature
Increased
evaporation
More cloud
Climate temperature remains constant
Less heat
escapes
+ve
More insulation
of heat
Increased
temperature
Increased
evaporation
More cloud
Climate temperature increases
Which is stable? What type of feedback is this?
Which is unstable? What type of feedback is this?
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.
Bibliography - Images





Slide 2 – The Earth from space – NASA -http://farm3.static.flickr.com/2084/2222523486_5e1894e314_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/human%20body/renarf/Zygote-3D-MaleHuman-Anatomy-Collec.jpg - August 30th 2010
 A Eukaryote cell - Chad Williams http://www.williamsclass.com/SeventhScienceWork/ImagesCells/EukaryoticCell.jpg - August 30th 2010
 Sydney Cityscape – Roger Waite -http://www.rogerswebsite.com/Australia/14%20%20Sydney%20City%20Skyline.jpg – August 30th 2010
 A Motorbike – Yamaha UK - http://www.yamaha-motor.co.uk/Images/2009-X-City-125-static-04_prv_tcm46280314.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.
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