Envi chap 2

negative feedback loop

In natural systems, scientists most often observe negative feedback loops, in which a system responds to a change by returning to its original state, or at least by decreasing the rate at which the change is occurring.

Describe the ways in which ecological systems depend on energy inputs.

Individual organisms rely on a continuous input of energy in order to survive, grow, and reproduce. More organisms can live where more energy is available.

Explain the components and states of matter.

Matter is composed of atoms, which are made up of protons, neutrons, and electrons. Atoms and molecules can interact in chemical reactions in which the bonds between particular atoms may change. Matter cannot be created or destroyed, but its form can be changed.

Matter

anything that occupies space and has mass.

open system

exchanges of matter or energy occur across system boundaries. Most systems are open. Even at remote Mono Lake, water flows in, and birds fly to and from the lake. The ocean is also an open system. Energy from the Sun enters the ocean, warming the waters and providing energy to plants and algae. Energy and matter are transferred from the ocean to the atmosphere as energy from the Sun evaporates water, giving rise to meteorological events such as tropical storms, in which clouds form and send rain back to the ocean surface. Matter, such as sediment and nutrients, enters the ocean from rivers and streams and leaves it through geologic cycles and other processes.

Distinguish between various forms of energy and discuss the first and second laws of thermodynamics.

Energy can take various forms, including energy that is stored (potential energy) and the energy of motion (kinetic energy). According to the first law of thermodynamics, energy cannot be created or destroyed, but it can be converted from one form into another. According to the second law of thermodynamics, in any conversion of energy, some energy is converted into unusable waste energy, and the entropy of the universe is increased.

Define systems within the context of environmental science.

Environmental systems are sets of interacting components connected in such a way that changes in one part of the system affect the other parts. Systems exist at multiple scales, and a large system may contain smaller systems within it. Earth itself is a single interconnected system.

positive feedback loop.

Positive feedbacks also occur in the natural world. FIGURE 2.21b shows an example of how births in a population can give rise to a positive feedback loop. The more members of a species that can reproduce, the more births there will be, creating even more of the species to give birth, and so on.

Explain how scientists keep track of inputs, outputs, and changes to complex systems.

Systems can be open or closed to exchanges of matter, energy, or both. A systems analysis determines what goes into, what comes out of, and what has changed within a given system. Environmental scientists use systems analysis to calculate inputs to and outputs from a system and its rate of change. If there is no overall change, the system is in steady state. Changes in one input or output can affect the entire system.

mass

The mass of an object is defined as a measure of the amount of matter it contains.

feedback

The term feedback means that the results of a process feed back into the system to change the rate of that process. Feedbacks, which can be diagrammed as loops or cycles, are found throughout the environment.

Describe how natural systems change over time and space.

Variation in environmental conditions, such as temperature or precipitation, can affect the types and numbers of organisms present. Short-term and long-term changes in Earth's climate also affect species distributions.

closed system,

matter and energy exchanges across system boundaries do not occur. Closed systems are less common than open systems. Some underground cave systems are nearly completely closed systems.

steady state

that is, whether inputs equal outputs, so that the system is not changing over time. This information is particularly useful in the study of environmental science. For example, it allows us to know whether the amount of a valuable resource or harmful pollutant is increasing, decreasing, or staying the same.