Environment

Environment

1. Definitions

   • Environment: Everything that surrounds and influences an organism
   • Environmental: Focuses on the relationship between people and the natural environment
   • Scientific method: Is what the scientist use to determine what is occurring in the natural world
     • Steps
       • 1. Collect facts
       • 2. Develop a scientific hypothesis
       • 3. Construct experiments to validate the hypothesis
       • 4. Accept, modify, or reject the hypothesis

2. System: Dynamic and complex whole, interacting as a structured functional unit with energy, material and information flowing among the elements

   • Ways to study a system
     • Holism: The system as a whole determinates how the parts behave
       • "The whole is more than the sum of the parts"
     • Reductionism: A complex system can be explained by reducing it to its fundamental parts
   • Perspectives to examine a system
     • Black Box: system or object which can be viewed in terms of its inputs and outputs (or transfer characteristics), without any knowledge of its internal workings
       • Thermodynamic system: Is the part of the universe that is under consideration
         • Boundary: Separates the system from its surroundings
           • Elements: The parts that constitute a system
           • Attributes: Characteristics of the elements
           • Relationships: Associations between elements and characteristics based on cause and effect
         • Environment: The rest of the universe apart from what is being studied
         • Thermodynamics: The science that describes the relationships between the different forms of energy
           • Energy in a system: All living things require energy. Their metabolism transforms energy into heat that is dissipated to the environment
           • Laws of thermodynamics
             • 1. Energy cannot be created nor destroyed
             • 2. The universe tends towards maximum disorder
       • Classification: Based on the nature of the boundary and the quantities flowing throw it
         • Isolated system: Doesn't exchange energy (heat and work) nor matter with the environment
         • Closed system: Exchange energy but not matter with the environment
         • Open system: Exchange energy and matter with the environment
     • White box: system or object which can be viewed in terms of its inputs and outputs (or transfer characteristics), with knowledge of its internal workings
   • System diagrams: Show the factors and relationships that are important and their effects
     • Simple relationship
       • Direct relationship
         • + if the factors move in the same way
       • Inverse relationships
         • - If the factors move in the opposite way
       • Linked relationship
         • Has both + and - because there are more than two factors
     • Complex relationships
       • Homeostasis: Property of a system that regulates its internal environment and tends to maintain a stable and constant condition
         • Homeostatic control mechanisms
           • The receptor: Monitors and responds to changes in the environment. When it senses a stimulus, sends information
           • The control centre: Sets the range at which a variable is mantained
           • The efector: corrects the deviation
             • Positive feedback: Mechanisms are designed to accelerate or enhance the output created by the stimulus
             • Negative feedback: Mechanisms reduce the output or activity of organs or systems back to its normal range of functioning
             • Feedback on complex relationships
               • Positive: Closed chains with an even number of negative relationships
                 • Signalled with a (+)
               • Negative: Closed chains with an odd number of negative relationships
                 • Signalled with a (-)