Systems and Models What are systems? Can be living or non living A cell, a car, a home, a farm Can be open, closed, or isolated Most in nature are open Definition: A set of inter-related parts working together to make a complex whole

Types of Systems Open Closed Isolated Exchanges matter and energy with its surroundings All ecosystems are open systems Closed Exchanges energy but not matter Earth is almost a closed system Isolated Exchanges nothing with environment Do not exist naturally Unless you count to whole universe

Systems Terminology Flows: When energy or matter move between storages Transfers When energy or matter flows and changes its location but does not change its state Ex: The movement of material in a non-living process (precipitation and water-flow from surface water to groundwater storage in the water cycle) The movement of energy (radiating from a warm body into a cooler atmosphere) The movement of material through living organisms (biomass being passed on as consumers eat organisms further down the food chain) Transformations A change in the chemical nature, state, or type of energy Matter transformation: Amino acids converted to protein Energy transformation: Ultraviolet light reflected from the Earth's surface as infrared light Energy-to-matter transformation: Photosynthesis converting sunlight energy with CO2 and water into glucose Transformation of state: Evaporation of water (transforms from liquid to gas) Storages: When energy or matter remains stationary for a period Systems Terminology

Models of Systems Can be physical or software Strengths Disadvantages Easier to work with than reality Can be used to predict the effect of change of input Can be applied to similar situations Help identify patterns Can be used to visualize small and large things Disadvantages Accuracy lost to simplicity If assumptions are wrong model collapses Predictions can be inaccurate