Buga

IB Environmental Systems and Societies
Unit 1 Systems and Models “Nautre Does nothing uselessly” Aristotle (384 – 322 BC)
Assessment statement
1.1.1 Outline the concept and characteristics of systems. Apply the systems concept on a range of scales.

Teacher’s notes
The emphasis will be on ecosystems but some mention should be made of economic, social and value systems. The range must include a small-scale local ecosystem, a large ecosystem such as a biome, and Gaia as an example of a global ecosystem.

1.1.2

1.1.3

Define the terms open system, closed system and isolated system.

These terms should be applied when characterizing real systems. • • An open system exchanges matter and energy with its surroundings (for example, an ecosystem). A closed system exchanges energy but not matter; the “Biosphere II” experiment was an attempt to model this. Strictly, closed systems do not occur naturally on Earth, but all the global cycles of matter, for example, the water and nitrogen cycles, approximate to closed systems.

• An isolated system exchanges neither matter nor energy. No such systems exist (with the possible exception of the entire cosmos).

1.1.4

The first law concerns the conservation of energy. The second law explains the second laws of thermodynamics dissipation of energy that is then not available to do work, bringing about disorder. The second law is most simply stated as: “In any isolated system entropy tends are relevant to environmental to increase spontaneously.” This means that energy and materials go from a systems. concentrated into a dispersed form (the availability of energy to do work diminishes) and the system becomes increasingly disordered. Describe how the first and

Both laws should be examined in relation to the energy transformations and maintenance of order in living systems.

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Assessment statement 1.1.5 Explain the nature of equilibria.

Teacher’s notes A