Systems and models

1. Systems and models A way of systematically figuring out how things interact.

2. 3rd rock from the sun. The Earth from space

3. 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

4. The Layers of Earth

5. 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: Predation, temperature, parasitism, humidity, competition, light intensity, season, soil pH, mutualism,

6. 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.)

7. Some examples of systems: Sydney Cityscape A Eukaryote cell A motorbike Human anatomy

8. To make a system diagram there are some conventions:

9. Using the model below, draw your own systems diagram for the following: Inputs • A candle • A mobile phone • A green plant • You • A forest • A Lake • A scooter • A cell • A city flows Storages flows Outputs Taken from page 72, Environmental Systems and Societies – Course Companion – Jill Rutherford - 2009 - Oxford

10. 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.)

11. Biosphere 2 • http://en.wikipedia.org/wiki/Biosphere_2 • http://www.biospherics.org/experimentchrono1.html • Was Biosphere 2 open, closed or isolated? Explain why? • Why was NASA so interested in what went on at Biosphere 2?

12. 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

13. 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.

14. 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. )

15. …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.

16. 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.

17. Energy losses: (Normally 2% efficiency) • 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 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%

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

19. Equilibria - balances • Equilibrium is the tendency of a system to return to an original state after it gets disturbed. • Steady state – stuff goes into the system stuff; goes out of the system; the amount of stuff in the system stays the same. • Static – nothing goes in; nothing comes out; the amount of stuff in the system stays the same.

20. 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.

21. Some stable systems resist change: • Sometimes the change is so great it moves to a NEW stable position:

22. 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.

23. 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?

24. 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.

25. 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-Male-Human-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_tcm46-280314.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.