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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.
