Dear Students of Diploma Year go through the following notes. I hope these short notes will give you clear idea about what we disccused during lecture>>>>
Systems Types
• 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

Law of Thermodynamics
The first law concerns the conservation of energy.: Energy nor can be created neither destroyed.
Energy cannot be created or destroyed, only transformed from one form to another. There is a fixed amount of energy in the universe. Therefore living organisms must get their required energy from their environment and surroundings.
The second law explains the 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 to increase spontaneously.” This means that energy and materials go from a concentrated into a dispersed form (the availability of energy to do work diminishes) and the system becomes increasingly disordered.
Both laws should be examined in relation to the energy transformations and maintenance of order in living systems.

Equilibrium
Entropy measures the amount of disorder in the universe – usable energy is more organized whereas less-usable energy is more diffuse/disorganized. Entropy increases naturally, or spontaneously.
A steady-state equilibrium should be understood as the common property of most open systems in nature.
A static equilibrium, in which there is no change, should be appreciated as a condition to which natural systems can be compared. (Since there is disagreement in the literature regarding the definition of dynamic equilibrium, this term should be avoided.)
however, that some systems may undergo longterm changes to their equilibrium while retaining an integrity to the system (for example, succession). The relative stability of an equilibrium—the tendency of the system to return to that original equilibrium following disturbance, rather than adopting a new one— should also be understood.
The self-regulation of natural systems is achieved by the attainment of equilibrium through feedback systems.

Feedback Systems

• Negative feedback is a self-regulating method of control leading to themaintenance of a steady-stateequilibrium—it counteracts deviation, forexample, predator–prey relationships.
• Positive feedback leads to increasing change in a system—it acceleratesdeviation, for example, the exponentialphase of population growth.
Feedback links involve time lags.

Transfer and Transformation
Transfers normally flow through a system and involve a change in location.
Transformations lead to an interaction within a system in the formation of a new end product, or involve a change of state. Using water as an example, run-off is a transfer process and evaporation is a transformation process. Dead organic matter entering a lake is an example of a transfer process; decomposition of this material is a transformation process.

Source: IBDP ESS Guide