FOR MORE OF THIS COURSE AND ANY OTHER COURSES, TEST
BANKS, FINAL EXAMS, AND SOLUTION MANUALS
CONTACT US
Chapter 2
Science, Matter, Energy, and Systems
Summary
and Objectives
2-1 What do scientists do?
Science
is an endeavor to discover how nature works and to use that learned knowledge
to make predictions about future events. The natural world follows orderly
patterns, which, through observation and experimentation, can be understood. CONCEPT
2-1 Scientists collect data and develop theories, models, and laws about
how nature works.
1.
Describe the steps involved in
the scientific process. Distinguish among scientific hypothesis, scientific
theory, and scientific (natural) law.
2.
Distinguish between tentative
or frontier science, reliable science and unreliable science. Explain the
importance of peer review. Explain why
people often use the term theory incorrectly.
3.
What are some limitations of
science? Describe statistics and
probability, and describe how they are used in science.
2-2 What is matter and what happens when it
undergoes change?
The building blocks of matter are atoms, ions, and
molecules, which form elements and compounds. These different aspects of matter
have mass and take up space; they may be living or non-living. CONCEPT 2-2A Matter consists
of elements and compounds that are in turn made up of atoms, ions, or
molecules. CONCEPT 2-2B When matter undergoes a physical or chemical
change, no atoms are created or destroyed (the law of conservation of matter).
4. Define matter. Distinguish between
forms of matter. Compare and contrast high-quality matter with low-quality
matter and give an example of each.
5. Distinguish among a proton (p), neutron
(n), and electron (e). What is the difference between the atomic number and the
mass number? What is an isotope?
6. Distinguish between organic compounds and
inorganic compounds.
7. What is the difference between a physical
change and a chemical change?
8. What is the law of conservation of matter?
2-3 What is energy and what happens when it
undergoes change?
Energy is the capacity to do work and transfer heat;
it moves matter. Thermodynamics is the study
of energy transformation. CONCEPT 2-3A Whenever energy is converted from one form to another
in a physical or chemical change, no energy is created or destroyed (first law
of thermodynamics). CONCEPT 2-3B Whenever energy is converted from one
form to another in a physical or chemical change, we end up with lower-quality
or less usable energy than we started with (second law of thermodynamics).
9. Define energy. Distinguish between
forms of energy and quality of energy. Distinguish between high-quality energy
and low-quality energy and give an example of each.
10. Describe how the law of conservation of
matter and the law of conservation of energy govern normal physical and
chemical changes. Briefly describe the second law of thermodynamics. Explain why this law means we can never
recycle or reuse high-quality energy.
2-4 What keeps us and other organisms
alive?
Ecology
is the study of connections in the natural world among organisms, populations,
communities, ecosystems, and the biosphere. The earth's life-support system
consists of the geosphere, biosphere, hydrosphere, and atmosphere. CONCEPT
2-4 Life is sustained by the flow of energy from the sun through the
biosphere, the cycling of nutrients within the biosphere, and gravity.
11. Distinguish between organism, species,
population, community, ecosystem, and biosphere.
12. Explain genetic diversity and how it
contributes to biological communities.
13. Distinguish between the atmosphere, troposphere,
and stratosphere. Define greenhouse gases and give two examples. What is the natural greenhouse effect?
14. List four spheres that interact to sustain
life on Earth. Compare the flow of matter and the flow of energy through the
biosphere.
2-5 What are the major components of an
ecosystem?
Ecosystems are made up of abiotic (nonliving) components: water,
air, nutrients, and solar energy, as well as biotic (living) components:
plants, animals, and microbes.
Producers, consumers, and decomposers cycle matter, energy, and
nutrients in an ecosystem. CONCEPT 2-5 Ecosystems contain nonliving and
living components, including organisms that produce the nutrients they need,
organisms that get the nutrients they need by consuming other organisms, and
organisms that recycle nutrients by decomposing the wastes and remains of other
organisms.
15. Distinguish between biotic and abiotic
components of the biosphere and give two examples of each.
16. Define range of tolerance and the limiting
factor principle. Give one example of a limiting factor in an ecosystem.
17. Distinguish between producers, consumers,
and decomposers. List and distinguish between two types of producers and four
types of consumers. Describe the concept
of trophic levels.
2-6 What happens to energy in an ecosystem?
Ecological interdependence can be described in food
chains and webs, energy flow, ecological efficiency, and the production of
biomass. CONCEPT 2-6 As energy flows through ecosystems in food chains
and webs, the amount of chemical energy available to organisms at each
succeeding feeding level decreases.
18. Apply the second law of energy to food chains
and pyramids of energy flow. Explain
ecological efficiency.
19. Discuss the difference between gross
primary productivity and net primary productivity.
2-7 What happens to matter in an ecosystem?
Major cycles in ecosystems are the nutrient cycle, the
hydrologic cycle, the carbon cycle, the nitrogen cycle, the phosphorus cycle,
and the rock cycle. The carbon cycle produces carbon dioxide, and with
more of it being released into the atmosphere, the world is now being affected
by global warming. CONCEPT 2-7 Matter, in the form of nutrients, cycles
within and among ecosystems throughout the biosphere, and human activities are
altering these chemical cycles.
20.
Describe the hydrologic
(water), carbon, nitrogen, or phosphorus cycle and describe how human activities
are affecting each cycle.
21.
List three types of rock and
describe their interactions through the rock cycle.
Key Terms
science
data
experiments
scientific
hypothesis
model
scientific theory
peer review
scientific law
(law of nature)
tentative or frontier science
reliable science
reliable science
unreliable
science
probability
matter
element
compounds
atom
atomic theory
neutrons
protons
electrons
nucleus
atomic number
mass number
isotopes
molecule
chemical formula
ion
acidity
pH
organic compounds
inorganic compounds
genes
trait
chromosome
cell
matter
quality
high-quality
matter
low-quality
matter
physical
changechemical change or reaction
law of
conservation of matter
energy kinetic
(moving) energy
heat
electromagnetic
radiation
potential
(stored) energy
principle of
sustainability
energy quality
high-quality
energy
low-quality
energy
first law of thermodynamics
law of conservation of energy
second law of thermodynamics
law of conservation of energy
second law of thermodynamics
ecology
organism
species
population genetic
diversity
habitat
community
biological
community
ecosystem
biosphere
atmosphere troposphere greenhouse gases
stratosphere
hydrosphere
geosphere
biomes
aquatic life
zones
nutrients
natural greenhouse effect
biotic
abiotic
range of tolerance
limiting factors
limiting factor principle
trophic level
producers
autotrophs
photosynthesis
consumers
heterotrophs
primary consumers
herbivores
carnivores
secondary consumers
tertiary consumers
omnivores
decomposers
detritus feeders
detritivores
aerobic respiration
ecological tipping point
food chain
food web
biomass
ecological efficiency
pyramid of energy flow
gross primary productivity
(GPP)
net primary productivity
(NPP)
biogeochemical cycles
nutrient cycles
hydrologic (water) cycle
evaporation
precipitation
transpiration carbon cycle
nitrogen cycle
phosphorus cycle
rock
igneous rock
sedimentary rock
metamorphic rock
rock cycle
Outline
2-1 What
Do Scientists Do?
A. Science
assumes that events in the natural world follow orderly patterns and that, through
observation and experimentation, these patterns can be understood. Scientists
collect data, form hypotheses, and develop theories, models, and laws to
explain how nature works.
1. Scientists identify a
problem, find out what is known about the problem, ask a question to
investigate, and conduct experiments to collect data in order to answer the
question.
2. Based on observations of
phenomenon, scientists form a scientific hypothesis—a possible explanation of
the observed phenomenon that can be tested.
3. Using the hypothesis,
scientists make testable projections and perform further experiments (or
observations) in order to accept or reject the hypothesis. (See Science Focus:
Statistics and Probability)
4. Important features of
the scientific process are curiosity, skepticism, reproducibility, and peer
review.
B. A
scientific theory is a verified, believable, widely accepted scientific
hypothesis or a related group of scientific hypotheses.
1. Theories are
explanations that are likely true, supported by evidence.
2. Theories are the most
reliable knowledge we have about how nature works.
C. A
scientific/natural law describes events/actions of nature that reoccur in the
same way, over and over again (such as effects of gravity on falling objects).
D. The reliability
of scientific results relies on the reliability of how the experiments are
conducted and interpreted.
1. Preliminary scientific
results can be described as tentative science (or frontier science). These results have not yet been widely tested
or accepted by peer review, yet they are often featured in news headlines. These results are not reliable, as they have
not been extensively tested. Scientists
may disagree over the interpretation and accuracy of the data and conclusions.
2. Reliable science, or
scientific consensus, is hypotheses, models, theories, and laws that are widely
accepted by most scientists that are experts in that field of study. These results have been peer reviewed and are
reproducible.
3. Unreliable science is
that which has not undergone peer review or has been discarded as a result of
peer review.
E. Limitations
of Science
1. There is always some
degree of uncertainty in scientific measurements, models, observations.
2. Scientists are human and
may be biased. Peer review greatly
reduces this.
3. Many systems in science
(especially environmental science) are very complex, making it difficult to
test each variable. Mathematical models
help simply complex analyses and modeling.
4. Statistical tools such
as sampling and estimation are important aspects of models.
5. The scientific process
can tell us about the natural world, not about the moral or ethical questions
related to the topic being examined.
2-2 What
Is Matter and What Happens When It Undergoes Change?
A. Matter
is anything that has mass and takes up space, living or not.
1. An element is the
distinctive building block that makes up every substance.
2. A compound is two or
more different elements held together in fixed proportions by chemical bonds.
B. The
building blocks of matter are atoms, ions, and molecules.
1. An atom is the smallest
unit of matter that exhibits the characteristics of an element.
2. An ion is an
electrically charged atom or combination of atoms.
3. A compound is a
combination of two or more atoms/ions of elements held together by chemical
bonds.
C. An atom
contains a nucleus with protons, usually neutrons, and one or more electrons
moving outside the nucleus; it has no electrical charge.
1. Subatomic particles in
an atom are of three types:
a. Protons have a positive
electrical charge.
b. Neutrons have no
electrical charge.
c. Electrons have a
negative electrical charge.
2. The nucleus is the very,
very small center of the atom.
3. Each element has its own
atomic number that equals the number of protons in the nucleus of each atom. [H
has 1 proton and, therefore, the atomic number of 1; uranium has 92 protons and
an atomic number of 92.]
4. Most of an atom's mass
is found in the nucleus. The mass number
is the total number of neutrons and protons in its nucleus.
D. All
atoms of an element have the same number of nuclei protons; but they may have
different numbers of uncharged neutrons in their nuclei. As a result, atoms may
have different mass numbers. These are called isotopes.
E. Molecules
are combinations of atoms held together by chemical bonds. Chemical formulas
show the number and type of atoms or ions in the compound.
1. Each of the elements in
the unit is represented by symbols: H=water, N=nitrogen.
2. Subscripts show the
number of atoms/ions in the unit.
F. Ions
are atoms with a net positive or negative electrical charge, resulting from the
gain or loss of electrons (respectively).
Ions are important for measuring a substance's acidity in water.
G. Organic
compounds contain combinations of carbon atoms and atoms of other elements.
Only methane (CH4) has only one carbon atom.
1. Hydrocarbons: compounds
of carbon and hydrogen atoms. Examples
include methane (component of natural gas) and octane (component of gasoline)
2. Chlorinated hydrocarbons:
compounds of carbon, hydrogen, and chlorine atoms. Examples include the pesticide DDT.
3. Simple carbohydrates
(simple sugars): specific types of compounds of carbon, hydrogen, and oxygen
atoms. Example: glucose
4. Macromolecules are
larger, more complex organic compounds, many of which are essential to
life. These include complex
carbohydrates (cellulose, starch), proteins, and nucleic acids (DNA, RNA).
5.
DNA contains genes, specific
sequences that code for traits that can be passed to offspring. These genes make up chromosomes, DNA that is
highly organized and tightly wrapped around proteins. These building blocks come together to form
cells, the fundamental unit of living things.
H. According
to the usefulness of matter as a resource, it is classified as having high or
low quality.
1. High-quality matter is
highly concentrated, often found near the earth's surface.
2. Low-quality matter is
dilute, may be found deep underground and/or dispersed in air or water.
I.
Although matter can change forms or re-combine into new substances, it
cannot be created or destroyed.
1. Physical change: no change in the chemical
composition of the matter.
2. Chemical change: chemical compositions do change; new
compounds are formed. Chemical
equations show how atoms and ions are rearranged to form new products.
3. Law of conservation of mater: atoms are not created or destroyed during
physical or chemical changes.
4. This law means there is no “away” when we
“throw something away”. We will always
have to address the pollutants and wastes that we produce.
2-3 What
Is Energy and What Happens When It Undergoes Change?
A. Energy
is the capacity to do work and transfer heat; it moves matter.
1. Kinetic energy has mass
and speed; wind, electricity, and heat are examples.
2. Electromagnetic
radiation is a form of kinetic energy in which energy travels in the form of a
wave. These waves have many forms as
described by their differing energy contents: X rays, UV radiation, and visible
light are examples.
3. Potential energy is
stored energy, ready to be used; an unlit match, for example.
4. Potential energy can be
changed into kinetic energy. The direct
input of solar energy to the earth produces other indirect forms of renewable
energy, including wind, hydropower, and biomass.
5. Energy quality is measured by its
usefulness; high energy is concentrated and has high usefulness. Low energy is
dispersed and can do little work.
B. The
Laws of Thermodynamics govern energy changes
1. The First Law of Thermodynamics states that
energy can neither be created nor destroyed.
2. The Second Law of Thermodynamics states
that when energy is changed from one form to another, there is always less
usable energy; energy quality is depleted.
In energy changes, the resulting low-quality energy is often heat which
dissipates into the air.
3. In living systems, solar
energy is changed to chemical energy (food) and then in to mechanical energy
(moving, thinking, living). During each
conversion, high-quality energy is degraded and flows into the environment as
low-quality heat.
4.
The Second Law of
Thermodynamics also means we can never recycle high-quality energy to perform
useful work. Once the concentrated
energy is used, it is degraded to low-quality heat that dissipates into the
atmosphere.
2-4 What
Keeps Us and Other Organisms Alive?
A. Ecology
is the study of connections in the natural world. An ecologist’s goal is to try
to understand interactions among organisms, populations, communities,
ecosystems, and the biosphere.
1. An organism is any form
of life. The cell is the basic unit of life in organisms.
2. Organisms are classified
into species, which groups organisms similar to each other together.
B. A
population consists of a group of interacting individuals of the same species occupying
a specific area.
1. Genetic diversity explains that these
individuals may have different genetic makeup and, thus, do not behave or look
exactly alike.
2. The habitat is the place where a population
or an individual usually lives.
C. A
community represents populations of different species living and interacting in
a specific area – the network of plants, animals, and microorganisms. (See
Science Focus: Have You Thanked the Insects Today?)
D. An
ecosystem is a community of different species interacting with each other and
with their nonliving environment of matter and energy. All of the earth’s
diverse ecosystems comprise the biosphere.
E. Various
interconnected spherical layers make up the earth’s life support system.
1. The atmosphere is the
thin membrane of air around the planet.
The troposphere (up to 17 km above sea level) contains air we breathe,
our weather, and greenhouse gases, while the stratosphere (17-50 km above
earth) holds the UV-protective ozone layer.
2. The hydrosphere consists
of the Earth's water (liquid, ice, and vapor)
3. The geosphere is made of
rock mostly inside the earth: crust, mantle, and core.
4. The biosphere contains
all life on earth, including parts of the atmosphere, hydrosphere, and
geosphere. Land regions are classified into biomes (forests, deserts,
grasslands) with distinct climates and animals/vegetation specifically adapted
to them. Biosphere extends from ocean
floor to 9 km above the earth's surface.
F. High-quality
energy from the sun, nutrient cycles, and gravity sustain life on Earth.
G. Solar
energy reaches the earth in the form of visible light, infrared radiation
(heat), and ultraviolet radiation.
1. Much of this energy is
absorbed or reflected back into space by the atmosphere.
2. Greenhouse gases trap
the heat and warm the troposphere. This natural greenhouse effect makes the
planet warm enough to support life.
2-5 What
Are the Major Components of an Ecosystem?
A. The
major components of ecosystems are abiotic (nonliving) water, air, nutrients,
and solar energy; and biotic (living) plants, animals, and microbes.
B. Each
population in an ecosystem has a range of tolerance to variations in its
physical and chemical environments.
1. The limiting factor principle states that
too much or too little of any abiotic factor can limit or prevent growth of a
population, even if all other factors are at or near the optimum range of
tolerance.
2. Water or nutrients can be limiting factors
on land, while dissolved oxygen, nutrients, and temperature can be limiting
factors in aquatic systems.
C. Every
organism in an ecosystem can be classified according to its trophic level
(feeding level), as defined by its source of nutrients.
1. Producers: autotrophs make their own
food/nutrients (plants). All consumers
rely on producers for their nutrients.
2. Consumers: heterotrophs may feed on both
producers (plants) and other consumers (animals), or may feed on plants alone
(herbivores).
3. Decomposers: detritivores feed on wastes
and dead organisms and recycle the nutrients back to the ecosystem – key role
in nutrient cycling. (See Science Focus:
Many of the World’s Most Important Species Are Invisible to Us)
2-6 What
Happens to Energy in an Ecosystem?
A. Food
chains and food webs help us understand how producers, consumers, and
decomposers are connected to one another as energy flows through trophic levels
in an ecosystem.
B. The
chemical energy stored in biomass is transferred from one trophic level to
another, but some energy is degraded and lost to the environment as low-quality
heat. As you go “up” the food chain,
there is a decrease in the amount of high-quality energy available to each
organism at succeeding feeding levels.
1. The percentage of usable chemical energy
transferred as biomass from one trophic level to the next is called ecological
efficiency.
2. Typically, 10% of usable chemical energy is
transferred to the next level in the food chain.
3. Energy flow pyramids illustrate how the
earth could support more people if they eat at a lower trophic level. Food webs and food chains rarely have more
than 4 or 5 trophic levels due to the significant loss of energy at each level.
C. Production
of biomass takes place at different rates among different ecosystems.
1. The rate of an
ecosystem’s producers converting energy as biomass is the gross primary
productivity (GPP).
2. Some of the biomass must
be used for the producer’s own respiration. Net primary productivity (NPP) is
the rate at which producers use photosynthesis to store biomass minus the rate
at which they use energy for aerobic respiration. NPP measures how fast
producers can provide biomass needed by consumers in an ecosystem.
3. The planet’s NPP limits
the number of consumers who can survive (including humans!).
4. Ecologists estimate that
humans now use, waste, or destroy 10-55% of the earth's entire potential NPP.
2-7 What
Happens to Matter in an Ecosystem?
A. Nutrient
cycles (biogeochemical cycles) are global recycling systems that interconnect
all organisms.
1. Nutrient atoms, ions,
and molecules continuously cycle between air, water, rock, soil, and living
organisms.
2. These cycles include the
carbon, oxygen, nitrogen, phosphorus, and water cycles. They are connected to
chemical cycles of the past and the future.
B. The
water/hydrologic cycle collects, purifies, and distributes the earth’s water in
a vast global cycle.
1. Solar energy evaporates
water, the water returns as rain/snow, goes through organisms, goes into bodies
of water, and evaporates again.
2. Some water becomes
surface runoff; returning to streams/rivers, causing soil erosion, and also
being purified itself.
3.
Water is a major medium for
transporting nutrients within and between ecosystems.
4.
About 0.024% of the earth's
water supply is available as liquid fresh water in accessible groundwater
deposits, lakes, rivers, and streams.
C. The
water cycle is altered by man’s activities.
1. We withdraw large
quantities of fresh water, often at a rate at is faster than nature can replace
it.
2. We clear vegetation,
which increases runoff, reduces filtering, and increases flooding.
3. We increase flooding
when we drain wetlands for farming or development.
D. The
carbon cycle circulates through the biosphere. Carbon moves through water and
land systems, using processes that change carbon from one form to another.
1. CO2 gas is an important temperature regulator on
Earth.
2. Photosynthesis in
producers and aerobic respiration in consumers, producers, and decomposers
circulates carbon in the biosphere.
3. Fossil fuels contain
carbon; in a few hundred years we have almost depleted these fuels that have
taken millions of years to form.
E. Addition
of excess carbon dioxide to the atmosphere through our use of fossil fuels and
our destruction of the world’s photosynthesizing vegetation has contributed to
changes in global climate
F. Bacteria
are critical to the nitrogen cycle, converting nitrogen compounds into those
that can be used by plants and animals as nutrients.
1. In nitrogen fixation,
gaseous N2 is converted to ammonia, which is converted to ammonium ions
that are useful to plants.
2. Ammonia not used by
plants may undergo nitrification, a conversion process that uses bacteria to
convert the nitrogen to nitrite ions (toxic to plants) and nitrate ions (easily
taken up by plants).
3. Decomposer bacteria convert
detritus into ammonia and ammonium ion salts in ammonification.
4. In denitrification,
nitrogen is returned to a gaseous form and released into the atmosphere.
G. Human activities affect the nitrogen cycle.
1. In burning fuel, we add
nitric oxide into the atmosphere; it can return to the earth’s surface as acid
rain.
2. Nitrous oxide that comes
from livestock, wastes, and inorganic fertilizers we use on the soil can warm
the atmosphere and deplete the ozone layer.
3. We destroy forest,
grasslands, and wetland, thus releasing large amounts of nitrogen into the
atmosphere.
4. We pollute aquatic
ecosystems with agricultural runoff and human sewage.
5. We remove nitrogen from
topsoil with our harvesting, irrigating, and land-clearing practices.
H. The phosphorous
cycle circulates through the water, the earth's crust, and living organisms.
1. Phosphate ions
transferred throughout the food chain, from producers to consumers to
decomposers.
2. Phosphates that end up
in the ocean can remain trapped in sediment for millions of years
3. Phosphates are often
limiting factors for plant growth on land as well as producer populations in
aquatic environments.
4. an interferes with the
phosphorous cycle in harmful ways such as mining phosphate rock to produce
fertilizers and detergents, cutting down tropical forests, and increasing
phosphates in aquatic environments with animal waste runoff and human sewage.
I. The
planet’s slowest cyclical process is the rock cycle.
1. Igneous rock forms when
magma (volcanic rock material) comes from the earth’s crust, cools, and
hardens.
2. Sedimentary rock is
formed when sediment is weathered and eroded, moved from its source, and
deposited in a body of water. The layers weather, erode, and become buried and
compacted. This process binds the particles together and forms sedimentary
rock, rocks such as sandstone and shale.
3.
When rock is exposed to high
temperatures, high pressures, chemically active fluids, or a combination of
these things, metamorphic rock is formed.
4.
The rock cycle concentrates the
earth's nonrenewable mineral resources (on which we depend).
Teaching Tips
1. Remember when planning for the lesson, take
a moment to go back and review the performance objectives listed under each key
concept. Build these performance objectives into the lesson, using them as
checkpoints for student understanding as the lesson unfolds. Also, take these
performance objectives into consideration when incorporating outside
material(s) into the lesson.
2. Recall that using informal questioning methods
each session can be highly effective in helping assess what the students
already know about a topic(s) before a lesson begins, and will also reveal the
general knowledge base of the class. When using this method, be aware that
sometimes you may expose a topic that students have little prior knowledge of
or misconceptions about. If this occurs, focus attention on preparing the
students for the information to come. Try to make a relevant connection between
something the students are already familiar with and what they are about to
learn.
3. Critical thinking activities are an
excellent element to incorporate into each class meeting. The following is a
possible warm-up activity for Chapter Two that can also be found under the
Activities and Projects section.
How do you feel when your
home is air conditioned? Heated? How do you feel when you turn on a light? The
television? Your CD player? What rights do you have to Earth’s energy
resources? Are there any limits to your rights? What are they?
4.
Have the students come back and
revise their answers after the completion of the lesson. Depending on
the class size, you may want to have the students share what they have learned
with one another in small groups or as a class.
Topics for Term Papers and Discussion
Conceptual Topics
1. Low-energy lifestyles. Individual case
studies such as Amory Lovins and national case studies such as Sweden. Many local, regional, and national
organizations are providing information for decreasing individual's energy use.
2. Nature’s cycles and economics. Recycling
attempts in the United States; bottlenecks that inhibit recycling; strategies
that enhance recycling efforts. What
types of recycling programs are available in your area?
3. Cycles of matter. Particular cycles of matter,
clarifying chemical changes throughout the cycle; the processes of
photosynthesis and respiration, and how they connect autotrophic and
heterotrophic organisms.
4. Energy flow. Energy flow in a particular
ecosystem; relationships between species in a particular ecosystem; comparison
of the life of a specialist with that of a generalist.
5. Humans trying to work with ecosystems.
Composting; organic gardening; land reclamation; rebuilding degraded lands;
tree-planting projects; landscaping with native plants.
Attitudes & Values
1. How much are you willing to pay in the short
run to receive economic and environmental benefits in the long run? Explore
costs and payback times of energy-efficient appliances, energy-saving light
bulbs, or hybrid vehicles.
2. Can we get something for nothing? Explore the
attempts of advertising to convince the public that we can indeed get something
for nothing. What does it mean when people say “there's no such thing as a free
lunch”? How do these factors impact our
perceived wants and needs?
3. Is convenience more important than
sustainability? Explore the influence of U.S. frontier origins on the throwaway
mentality.
4. Do you hold any particular
feelings for producers? Consumers? Decomposers? How do you feel when you think
of a coyote eating a rabbit? How do you feel when you think of humans eating
hamburgers?
Should
we eat lower on the food chain?
5. Should we rely more on perpetual sources of
energy? What kinds of changes in our
energy sources do you expect to see in the coming 10-20 years?
6. What lessons for human societies can be drawn
from a study of species interaction in ecosystems?
7. To what extent should we disrupt and simplify
natural ecosystems for our food, clothing, shelter, and energy needs and wants? To what extent do we actually disrupt these
systems? What can individuals do to
change this?
8. What do nature’s cycles of matter suggest
about landfills, incinerators, reducing consumption, and recycling?
9. How do you feel when your home is air conditioned?
Heated? How do you feel when you turn on a light? The television? Your CD
player? What rights do you have to Earth’s energy resources? Are there any
limits to your rights? What are they?
10. Based on your current
understanding of energy flow and cycles of matter, evaluate the emphasis in the
United States on fossil fuels and nuclear power for energy production.
Action-Oriented Topics
1. Individual. Actions that improve energy
efficiency and reduce consumption of materials. Field and laboratory methods
used in ecological research. Measuring net primary productivity and respiration
rates; analyzing for particular chemicals in the air, water, and soil.
2. Community. Enhance recycling efforts:
curbside pickup versus recycling center dropoffs; high-tech versus low-tech
sorting of materials; Osage, Iowa, a case study in community energy efficiency.
3. Regional. Restoration of degraded ecosystems
such as Lake Erie; coastal zone management.
4. National energy policy. Evaluation of the
current national energy policy proposals in light of the laws of energy and
long-term economic, environmental, and national-security interests.
Activities and Projects
1. A human body at rest yields heat at about the
same rate as a 100-watt incandescent light bulb. As a class exercise, calculate
the heat production of the student body of your school, the U.S. population,
and the global population. Where does the heat come from? Where does it go?
2. As a class exercise, conduct a survey of the
students at your school to determine their degree of awareness and
understanding of the three matter and energy laws. Discuss the results in the
context of the need for sustainable-earth societies.
3. As a class exercise, have each student list
the kinds and amounts of food he or she has consumed in the past 24 hours.
Aggregate the results and compare them on a per capita basis with similar
statistics derived from studies of dietary composition and adequacy in
food-deficient nations. How many people with a vegetarian diet could subsist on
the equivalent food value of the meat consumed by your class?
4. Have the students debate the argument that
eating lower on the food chain is socially and ecologically more responsible,
cheaper, and healthier. (It is helpful to do this around a time when fasting is
common.) Also, look at the long-term picture: Will eating low on the food chain
sustain an exponentially growing human population indefinitely? What kinds of changes would this mean to your
diet? How willing are you to change?
5. Define an ecosystem to study on campus. As a
class project, analyze the nonliving and living components of the ecosystem.
Draw webs and construct pyramids to show the relationships between species in
the ecosystem. Project what might happen if pesticides were used in the
ecosystem, if parts of the ecosystem were cleared for development, or if a
coal-burning power plant were located upwind.
6. Ask a physics professor or physics lab
instructor to visit your class and, by using simple experiments, demonstrate
the matter and energy laws.
7. Organize a class trip to a natural area such
as a forest, grassland, or estuary to observe the elements of ecosystem
structure and function. Arrange for an ecologist or naturalist to provide
interpretive services.
8. Bring a self-sustaining terrarium or aquarium
to class and explain the structure and function of this conceptually tidy
ecosystem. Discuss the various things that can upset the balance of the
ecosystem and describe what would happen if light, food, oxygen, or space were
manipulated experimentally.
BBC News Videos
The Brooks/Cole Environmental Science Video
Library with Workbook, featuring BBC Motion Gallery Video Clips, 2011. ISBN:
978-0-538-73355-7 (Prepared by David Perault)
Who Pays The Price for Technology?
Suggested Answers for Critical Thinking Questions
1. Student
answers will vary. They should
emphasize the process of observation, creating hypothesis to explain or predict
future behavior, testing the hypothesis, and then revising the hypothesis.
2. (a)
Scientists can disprove things but they cannot prove anything absolutely
because there is always some inherent uncertainty in making measurement,
observations, and using models. Yet, the
process of science means that many different experiments will be conducted from
many different perspectives to try and understand if there is a connection
between smoking and death. Scientific
consensus develops over time, and new ideas are continually evaluated to see if
a more accurate explanation can be developed.
(b) This statement misinterprets the meaning of a scientific theory. The natural greenhouse theory is reliable because a scientific theory is related to a body of observations or measurements that have been well-tested and widely-accepted by the scientific community.
3. This
phenomenon is not in violation of the law of conservation of matter because,
while the tree is growing, it is doing so through physical and chemical changes
without creating or destroying atoms. The tree is deriving matter in the form
of nutrients from the earth, water, and the atmosphere, and when it dies this
matter will be returned to their cycles.
4. The
second law of thermodynamics states that energy always goes from a more-useful
to a less-useful form when it is changed from one form to another. When a
barrel of oil is used for energy, most of the energy is given off as heat, a
lower-quality energy. You are unable to recycle or reuse the high-quality
energy because once it has been converted into low-quality energy, or heat, it
is lost to the environment.
5. (a)
Energy from the sun flows through living organisms in their feeding
relationships and out into the environment mainly as heat lost. The flow of
energy through the biosphere depends on the cycling of nutrients because producers
convert energy from the sun to nutrients for consumers and detritivores, which
recycle nutrients back to producers.
(b) The cycling of nutrients depends on gravity because it allows the planet to maintain its atmosphere. Gravity enables the movement and cycling of chemicals through the air, water, soil, and organisms.
5.
Student
answers will vary. Students should be
able to trace their foods back to a producer species – but it might take some
research for them to figure out what some of those intermediary organisms
eat. As the course progresses, students
may return to this thinking about their feeding level and the impact it has on
the environment.
7. (a)
If all the decomposers and detritus feeders were eliminated from an ecosystem,
waste and dead organisms would build up and there would be no cycling of
nutrients, as the detritivores aid in the breakdown of waste products into
basic nutrients needed to support life.
(b) If all the producers were eliminated from an ecosystem, consumers or heterotrophs would suffer as they have no way of producing their own energy. All higher trophic levels would also suffer and would most likely result in the halt of energy transfer through the ecosystem.
(c) If all insects were eliminated from an ecosystem, energy transfer and matter cycling through the ecosystem would be greatly altered. Insects fill important rolls such as detritivores and primary consumers; they also make up a major food/energy source to other organisms. Insects are also needed as pollinators for sexual reproduction in plants.
A balanced ecosystem cannot exist with only producers and decomposers. A healthy ecosystem depends on species diversity. Consumers maximize the rate of flow of energy and cycling of matter through ecosystems. All trophic levels are necessary for balanced nutrient cycling and energy flow.
8. Often,
farmers need to add fertilizer containing nitrogen and phosphorous to their
crops, without having to add carbon. The reason for this is because carbon is
far more abundant than nitrogen and phosphorous. Nitrogen or phosphorus is
often the limiting factor. They are essential nutrients for growing crops.
No comments:
Post a Comment