Summary of the Lecture Topic
Scientists use systems theory to understand
how things work. Systems theory suggests that you model
natural and human-made phenomena as a set of interrelated
components that work together to accomplish some kind
of process. Systems are used by humans in every day
life to describe the operation of a number of diverse
phenomena. Systems or models are also generalizations
of reality. One common way to present how things work
is with a graphical model. In this lecture, a graphical
model of how scientific understanding operates is presented
as an example of a system.
Systems tend to have similarities in
the way they work. Within their defined boundaries
systems contain three types of properties: elements,
attributes, and relationships. Elements are the things
that make up the system of interest. Attributes are
the perceived characteristics of the elements. Relationships
are descriptions of how the various elements (and their
attributes) work together to carry out some kind of
process. Systems also have the same common characteristics.
Seven characteristics are described.
Scientists have classified a number of
different system types. These types include: isolated
systems, closed systems, open systems, morphological
systems, cascading systems, process-response systems,
control systems, and ecosystems. The nature of each
of these types of systems is defined.
We often think about systems in an isolated
fashion. However, most systems have hierarchical connections
and structure. These connections can be to structures
that exist at smaller or larger scales. It is very
important to recognize that systems generally do not
exist in isolation.
An environmental system can be defined
as a system where life interacts with abiotic factors.
All environmental systems involve the capture, movement,
storage, and use of energy. This fact also makes them
energy systems. Energy is captured in the living components
of environmental systems by processes like photosynthesis,
biomass consumption, and biotic decomposition. Energy
is also used in environmental processes that are strictly
abiotic. For example, solar energy is responsible for
wind, weathering, and precipitation.
Equilibrium can be defined as the average
state of a system as measured through one of its attributes
or elements. Scientists have defined six different
types of equilibrium. Most systems maintain a steady
state equilibrium through the operation of positive
and negative feedback mechanisms. Negative-feedback
mechanisms control the state of the system by dampening
or reducing the size of the system's elements or attributes.
Positive-feedback mechanisms feed or increase the size
of one or more of the system's elements or attributes
over time. This section concludes by showing how negative
and positive feedbacks work to cause fluctuations in
the population size of aphids.
List of Key Terms
System, Cell, Closed
System, Community, Control
Ecosystem, Element, Energy, Entropy, Environmental
Fermentation, Fixed, Food
Metabolism, Model, Morphological
Equilibrium, Starch, Static
State Equilibrium, System, System
Study Questions, Problems
(1). What is a system? How do we use
them in the process of understanding?
(2). Describe the differences that
exist between morphological, cascading, and process-response
(3). Why does science attempt to understand
systems at the process-response level?
(4). Define the three kinds of properties
(elements, attributes and relationships) of systems
using an ecological food chain as an example.
(5). What is an equilibrium? Describe
some of the different types of equilibrium that exist
(6). Explain how do feedback mechanisms
regulate natural systems?