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Env. Sci. Final: Chapter 2
Terms in this set (79)
Earth's Environmental Systems. Systems involve feedback loops. What is a system?
a network of relationships among components that interact with and influence one another through the exchange of energy, matter, or information.
What is a feedback loop?
a system's output can serve as input to that same system, a circular process
What is a negative feedback loop?
output that results from a system moving in one direction acts as input that moves the system in the other direction.
What is a positive feedback loop?
Positive feedback loops have the opposite effect. Rather than stabilizing a system, they drive it further toward an extreme.
Ex. of positive feedback loop?this type of feedback loop accelerates a process and usually has no obvious means of being slowed or stopped.
child birth in mammals. occurs when a baby's head is pushed against the birth canal.
ex. of negative feedback loop?A change in which the variable being regulated brings about a response that moves the variable in the "opposite direction"
you are inside and at normal body temperature, then you go outside into the cold and your body temp begins to decrease(unintended event), your body responds by causing events that raise your temperature
Environmental systems interact: Natural systems can be categorized in many different ways. Scientists divide Earth's major components into structural spheres. What are they?
lithosphere, atmosphere, hydrosphere, and biosphere
CHEMISTRY AND THE ENVIRONMENT: What are the two chemical building blocks?
atoms and elements
What is the the law of conservation of matter?
Matter may be transformed from one type of substance into others, but it cannot be created or destroyed.
What is an element?
a fundamental type of matter, a chemical substance with a given set of properties that cannot be broken down into substances with other properties.
Elements needed in large quantities by organisms, such as ______, are called ________.
What are atoms?
the smallest units that maintain the chemical properties of the element.
What are ions? what are neutrons?
atoms that gain or lose electrons; atoms lacking an electrical charge
Atoms may also gain or lose electrons to become ____, electrically charged atoms or combination of atoms.
Atoms bond to form __________ and __________.
molecules and compounds
Atoms bond together and form molecules. What are molecules?
combinations of two or more atoms.
What is a compound?
A molecule composed of atoms from two or more different elements; ex CO2
What are ionic bonds?
Ions of differing charge bind with one another to form compounds with ionic bonds.
What are covalent bonds?
Atoms that lack an electrical charge combine by "sharing" electrons in covalent bonds.
Elements, molecules and compounds can come together in ______ without chemically bonding.
Air in the atmosphere is a solution of many constituents including:
nitrogen, oxygen, water vapor, methane, and ozone.
What ions determine acidity?
The pH scale is ________; each step represents a tenfold difference in hydrogen ion concentration.
Matter is composed of _______ and ________ compounds.
organic and inorganic compounds
What are Organic compounds?
consist of carbon atoms joined by bonds, and they may include other elements.
What are Inorganic compounds
? lack carbon-carbon bonds.
One class of organic compounds that is important in environmental science is the_________. What do hydrocarbons contain?
hydrocarbons; only atoms of carbon and hydrogen.
___________ are building blocks of life.
Three types of polymers (long chains of repeated molecules) are essential to life:
proteins, nucleic acids, and carbohydrates. Along with lipids,
What are polymers?
long chains of repeated molecules
What are these molecules referred as?
macromolecules because of their large sizes
What are proteins?
consist of long chains of organic molecules called amino acids.
Proteins: They serve many different functions in living cells including:
structural support, energy storage, immune system functions, hormones, and enzymes.
What are nucleic acids and what do they do?
direct the production of proteins. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) carry the hereditary information for organisms.
Nucleic acids are composed of _________. What do they contain?
nucleotides; each of which contains a sugar molecule, a phosphate group, and a nitrogenous base.
What are genes?
Regions of DNA that code for specific functions
What are carbohydrates?
include simple sugars that are three to seven carbon atoms long.
Among these is glucose which fuels living cells and serves as the base for ________ _____________.
What are complex carbohydrates?
include starch, an energy storage compound, chitin, a structural component of shells, and cellulose, the most abundant organic compound on earth which is found in the cell walls of plants.
What is chitin?
a structural component of shells
What are lipids?
fats. are a chemically diverse group of compounds, classified together because they do not dissolve in water.
What is energy?
is an intangible phenomenon that can change the position, physical composition, and temperature of matter.
What is chemical energy?
potential energy held in the bonds between atoms
The first law of thermodynamics states:
that energy can change from one form to another, but cannot be created or lost.
The second law of thermodynamics states:
that energy tends to change from a more-ordered state to a less-ordered state, as long as no force counteracts this tendency. Systems tend to move toward increasing disorder, or entropy.
Some organisms use the sun's _________ to produce their own food.Such organisms are called autotrophs or producers and include :
radiation; green plants, algae, and cyanobacteria.
The net process of photosynthesis is defined by the chemical equation:
6CO2 + 6H2O + the sun's energy → C6H1206 (sugar) + 6O2.
Animals depend on the _______ and ________ from photosynthesis.
sugars and oxygen
________ __________ releases chemical energy.
What is cellular respiration?
Organisms make use of the chemical energy created by photosynthesis
cellular respiration cont:
Cells employ oxygen to convert glucose back into its original starting materials, water and carbon dioxide, and release energy to form chemical bonds or perform other tasks within cells.
The net equation for cellular respiration is the exact opposite of that for photosynthesis:
C6H12O6 (sugar) + 6O2 → 6CO2 + 6H2O + energy.
When does respiration occur?
occurs in autotrophs and also in heterotrophs, or consumers, organisms that gain their energy by feeding on the biomass of other organisms.
As autotrophs convert solar energy to the energy of chemical bonds in sugars during photosynthesis, what do they perform?
The total amount of chemical energy produced by autotrophs is termed:
gross primary production
The energy that remains after respiration and is used to generate biomass, ecologists is called:
net primary production.
Ecosystems vary in the rate at which autotrophs convert energy to biomass. This rate is termed __________ and ecoysystems whose producers convert solar energy to biomass rapidly are said to have ______ _____ _______ productivity.
productivity; high net primary productivity
Nutrients circulate in ______________ cycles.
What do Nutrient cycles (or biogeochemical cycles) do?
circulate elements or molecules through the lithosphere, atmosphere, hydrosphere, and biosphere.
Nutrients move from one pool or reservoir to another, remaining for varying amounts of time in each. When a reservoir releases more materials than it accepts, it is called a _________.
and when a reservoir accepts more materials than it releases, it is called a ______.
The rate at which materials move between reservoirs is termed a ______.
The water cycle influences all other cycles. The water cycle, or _________ cycle, is an integral part of nutrient cycling on Earth.
hydrological: evaporation, transpiration, precipitation, runoff;
Some water soaks down through soil and rock through a process called _________ to recharge underground reservoirs known as _________.What are aquifers?
infiltration; aquifers; spongelike regions of rock and soil that hold groundwater, water found underground beneath layers of soil.
The uppermost level of groundwater held in an aquifer is referred to as the ________ _______. __________ activity has affected nearly every flux, reservoir, and residence time in the water cycle.
water table; human
What function is extensive in the carbon cycle?
What is the largest human impact of the carbon cycle?
through our use of fossil fuels as an energy source.
What ciculates a limited nutrient?
The phosphorus cycle
What rocks are the largest reservoir in the phosphorus cycle?
Human activities increase phosphorus concentrations in surface water how?
through substantial runoff of the phosphorus-rich fertilizers we apply to lawns and farmlands.
The _________ cycle involves specialized bacteria. Thus, the nitrogen cycle is of vital importance to us and to all other organisms.
What is an essential ingredient in the proteins, DNA, and RNA that build up our bodies, and is an essential nutrient for plant growth? it is of vital importance to us and to all other organisms.
To become biologically available, inert nitrogen gas must be "______," or combined with hydrogen in nature to form ammonia, whose water-soluble ions of ammonium can be taken up by plants.
Nitrogen fixation can be accomplished in two ways:
by the intense energy of lightning strikes, or by particular types of nitrogen fixing bacteria that inhabit the top layer of soil.
Other types of special bacteria then perform a process as nitrification, what is nitrification?
converting ammonium ions first into nitrite ions, then into nitrate ions.
What is nitrogen fixation?
The chemical processes by which atmospheric nitrogen is assimilated into organic compounds, esp. by certain microorganisms as part of the nitrogen cycle; the assimilation of atmospheric nitrogen by soil bacteria and its release for plant use on the death of the bacteria
Animals obtain the nitrogen that they need how?
by consuming plants or other animals.
The next step in the nitrogen cycle occurs when?
denitrifying bacteria convert nitrates in soil or water to gaseous nitrogen.
We have greatly influenced the nitrogen cycle. Human alterations to the nitrogen cycle have had profound impacts like what? Tackling nitrogen enrichment requires _______approaches.
eutrophication of aquatic ecosystems; diverse
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