population a group of organisms of the same species that live in a specific geographical area and interbreed
community a group of various species that live in the same habitat and interact with each other
ecosystem a community of organisms and their abiotic environment
habitat a place where an organism usually lives
niche the unique position occupied by a species, both in terms of its physical use of its habitat and its function
within an ecological community
biodiversity the variety of organisms in a given area, the genetic variation within a population, the variety of
species in a community, or the variety of communities in an ecosystem
climate the average weather conditions in an area over a long period of time
biome a large region characterized by a specific type of climate and certain types of plant and animal
communities
producer a photosynthetic or chemosynthetic autotroph that serves as the basic food source in an ecosystem
consumer an organism that eats other organisms (heterotroph) or organic matter instead of producing its own
nutrients or obtaining nutrients from inorganic sources
decomposer an organism that feeds by breaking down organic matter from dead organisms (usually bacteria
and fungi)
trophic level one of the steps in a food chain or food pyramid
energy pyramid a triangular diagram that shows an ecosystem's loss of energy, which results as energy passes
through the ecosystem's food chain
carbon cycle the movement of carbon from the nonliving environment into living things and back
respiration the exchange of oxygen and carbon dioxide between living cells and their environment
carrying capacity the largest population that an environment can support at any given time
predation an interaction between two organisms in which one organism, the predator, kills and feeds on the
other organism, the prey
parasitism a relationship between two species in which one species, the parasite, benefits from the other
species, the host, which is harmed
symbiosis a relationship in which two different organisms live in close association with each other
mutualism a relationship between two species in which both species benefit
commensalism a relationship between two organisms in which one organism benefits and the other is
unaffected
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Key Idea 6:
Plants and animals depend on each other and their physical environment.
The fundamental concept of ecology is that living organisms interact with and are dependent on their
environment and each other. These interactions result in a flow of energy and a cycling of materials that are
essential for life.
Competition can occur between members of different species for an ecological niche. Competition can also
occur within species. Competition may be for abiotic resources, such as space, water, air, and shelter, and for
biotic resources such as food and mates.
PERFORMANCE INDICATOR 1.1
Explain how diversity of populations within ecosystems relates to the stability of ecosystems.
1.1b An ecosystem is shaped by the nonliving environment as well as its interacting species. The world contains
a wide diversity of physical conditions, which creates a variety of environments.
1.1c In all environments, organisms compete for vital resources. The linked and changing interactions of
populations and the environment compose the total ecosystem.
1.1d The interdependence of organisms in an established ecosystem often results in approximate stability over
hundreds and thousands of years. For example, as one population increases, it is held in check by one or more
environmental factors or another species.
1.1e Ecosystems, like many other complex systems, tend to show cyclic changes around a state of approximate
equilibrium.
ECOSYSTEMS
> An ecosystem includes a community of organisms and their physical environment.
 A group of various species that live in the same place and interact with one another is called a
community.
 The group, along with the living and nonliving environment, make up an ecosystem.
 Relationships between organisms are examples of biotic factors that affect an ecosystem. Biotic
describes living factors in an ecosystem.
 The physical or nonliving factors of an environment are called abiotic factors. Examples of abiotic
factors are oxygen, water, rocks, sand, sunlight, temperature, and climate.
 A habitat is the place where an organism lives.
 The variety of organisms in a given area is called biodiversity.
 Physical factors can have a big influence on biodiversity. High or low temperatures, or limited food
or water can lower biodiversity.
 Ecosystems with high biodiversity are often more able to resist damage.
 Damage to ecosystems can be caused by severe weather events or human activities. Systems with
low biodiversity can be severely damaged easily.
 When biodiversity decreases in any ecosystem, that ecosystem is not as healthy as it could be.
MAJOR BIOLOGICAL COMMUNITIES
> Two key factors of climate that determine biomes are temperature and precipitation.
 The kinds of species that live in a particular place are determined partly by climate. Climate is the
average weather conditions in an area over a long period of time.
 A biome is a large region characterized by a specific kind of climate and certain kinds of plant and
animal communities.
 Most organisms are adapted to live within a particular range of temperatures and cannot survive at
temperatures too far above or below that range.
 Precipitation also determines the kinds of species that are found in a biome.
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PERFORMANCE INDICATOR 6.2
Explain the importance of preserving diversity of species and habitats.
6.2a As a result of evolutionary processes, there is a diversity of organisms and roles in ecosystems. This
diversity of species increases the chance that at least some will survive in the face of large environmental
changes. Biodiversity increases the stability of the ecosystem.
6.2b Biodiversity also ensures the availability of a rich variety of genetic material that may lead to future
agricultural or medical discoveries with significant value to humankind. As diversity is lost, potential sources of
these materials may be lost with it.
ECOSYSTEM RESILIENCY
> Interactions between organisms and the number of species in an ecosystem add to the resiliency of an
ecosystem.
 Ecosystems can be destroyed or damaged by severe weather, humans, or introduced species. Other
factors can help keep an ecosystem stable.
 Higher biodiversity often helps make an ecosystem more resilient.
 Predation can reduce the effects of competition among species.
 Predators can influence more than their prey. When predators eat one species, they may reduce
competition among other species.
1.1a Populations can be categorized by the function they serve. Food webs identify the relationships among
producers, consumers, and decomposers carrying out either autotrophic (producers: photosynthetic, plants &
algae) or heterotrophic (consumers: herbivores & carnivores) nutrition.
1.1f Every population is linked, directly or indirectly, with many others in an ecosystem. Disruptions in the
numbers and types of species and environmental changes can upset ecosystem stability.
WHAT IS A POPULATION?
> Understanding population growth is important because populations of different species interact and affect
one another, including human populations.
 A population is made up of a group of organisms of the same species that live together in one place at
one time and interbreed.
 Populations can be small or large. Some populations stay at nearly the same number for years at a time.
Some populations die out from lack of resources. Other populations grow rapidly.
POPULATION GROWTH
> Exponential growth occurs when numbers increase by a certain factor in each successive time period.
Logistic growth is population growth that starts with a minimum number of individuals and reaches a
maximum depending on the carrying capacity of the habitat.
 Whether a population grows or shrinks depends on births, deaths, immigration, and emigration.
— Immigration is the movement of individuals into a population.
— Emigration is the movement of individuals out of a population.
 A simple population model describes the rate of population growth as the difference between birthrate,
death rate, immigration, and emigration.
 Populations do not grow unchecked forever. Factors such as availability of food, predators, and disease
limit the growth of a population. Eventually, population growth slows and may stabilize.
 An ecosystem can support only so many organisms. The largest population that an environment can
support at any given time is called the carrying capacity.
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PERFORMANCE INDICATOR 6.1
Explain factors that limit growth of individuals and populations.
6.1a Energy flows through ecosystems in one direction, typically from the Sun, through photosynthetic
organisms including green plants and algae, to herbivores to carnivores and decomposers.
6.1b The atoms and molecules on the Earth cycle among the living and nonliving components of the biosphere.
For example, carbon dioxide and water molecules used in photosynthesis to form energy-rich organic
compounds are returned to the environment when the energy in these compounds is eventually released by cells.
Continual input of energy from sunlight keeps the process going. This concept may be illustrated with an energy
pyramid.
6.1c The chemical elements, such as carbon, hydrogen, nitrogen, and oxygen, that make up the molecules of
living things pass through food webs and are combined and recombined in different ways. At each link in a food
web, some energy is stored in newly made structures but much is dissipated into the environment as heat.
6.1d The number of organisms any habitat can support (carrying capacity) is limited by the available energy,
water, oxygen, and minerals, and by the ability of ecosystems to recycle the residue of dead organisms through
the activities of bacteria and fungi (decomposers).
6.1e In any particular environment, the growth and survival of organisms depend on the physical conditions
including light intensity, temperature range, mineral availability, soil/rock type, and relative acidity (pH).
6.1f Living organisms have the capacity to produce populations of unlimited size, but environments and
resources are finite. This has profound effects on the interactions among organisms.
FACTORS THAT AFFECT POPULATION SIZE
> Water, food, predators, and human activity are a few of many factors that affect the size of a population.
 Nonliving factors that affect population size are called abiotic factors. Weather and climate are the
most important abiotic factors.
 A factor that is related to the activities of living things is called a biotic factor. Food, such as grass or
other animals, is a biotic factor.
 Biotic factors can have a stronger influence when crowding exists; the effects of starvation, predators,
and disease often also increase.
 Humans affect populations of many species - humans cause populations to drop by disrupting habitats,
introducing diseases, or introducing nonnative species.
CARVING A NICHE
> A niche includes the role that the organism plays in the community. This role affects the other organisms in
the community.
 The unique position occupied by a species, both in terms of its physical use of its habitat and its
function in an ecological community, is called a niche.
 A niche is not the same as a habitat. A habitat is the place where an organism lives.
COMPETING FOR RESOURCES
> Competition for resources between species shapes a species' fundamental niche.
 The entire range of conditions where an organism or species could survive is called its fundamental
niche.
 Many species share parts of their fundamental niche with other species. Sometimes, species compete
for limited resources. Because of this competition, a species almost never inhabits its entire
fundamental niche.
 The actual niche that a species occupies in a community is called its realized niche.
 Sometimes, competition results in fights between rivals.
 Many competitive interactions do not involve direct contests. But when one individual takes a
resource, the resource is no longer available for another individual.
 Competition has several possible outcomes.
— Sometimes, one species wins, and the other loses. The loser is eliminated from the habitat.
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—
Other times, competitors can survive together in the same habitat. They are able to survive together
because they divide the resources.
 No two species that are too similar can coexist because they are too similar in their needs. One will be
slightly better at getting the resources on which they both depend.
The more successful species will dominate the resources. The less successful species will either die off
or have to move to another ecosystem.
Eventually, the better competitor will be the only one left. One species eliminating another through
competition is called competitive exclusion.
 Sometimes, competitors eat the same kinds of food and are found in the same places.
— These competitors divide resources by feeding in slightly different ways or slightly different places.
TROPHIC (energy) LEVELS
> In an ecosystem, energy flows from the sun to producers to consumers to decomposers.
 The primary source of energy for an ecosystem is the sun.
 Photosynthetic organisms, such as plants and algae, change light energy from the sun into energy that
they can use to grow.
— These photosynthetic organisms are producers, the basic food source for an ecosystem.
 Consumers are organisms that eat other organisms instead of producing their own food.
 Decomposers, such as bacteria and fungi, are organisms that break down the remains of animals.
 Each step in the transfer of energy through an ecosystem is called a trophic level.
 In ecosystems, energy flows from one trophic level to the next, forming a food chain.
The first trophic level of ecosystems is made up of producers. Plants, algae, and some bacteria use the
energy in sunlight to build energy-rich carbohydrates.
The second trophic level of a food chain is made up of herbivores, which eat producers. A cow is an
example of an herbivore.
The third trophic level includes animals that eat herbivores. Any animal that eats another animal is a
carnivore. Some carnivores are on the third trophic level because they eat herbivores.
Other carnivores are on the fourth trophic level or an even higher trophic level because they eat other
carnivores.
Omnivores, such as bears, are animals that are both herbivores and carnivores.
 In most ecosystems, energy does not follow a simple food chain. Energy flow is much more
complicated.
— Ecosystems almost always have many more species than a single food chain has. In addition, most
organisms eat more than one kind of food.
— This complicated, interconnected group of food chains is called a food web.
LOSS OF ENERGY
> Energy is stored at each link in a food web. But some energy that is used dissipates as heat into the
environment and is not recycled.
 When an animal eats food, it gets energy from the food.
 When the energy is used, about 90% of it is converted into heat energy and is dispersed into the
environment.
 Only about 10% is stored in the animal's body as fat or as tissue.
— This amount of stored energy is all that is available to organisms at the next trophic level that
consume the animal.
 An energy pyramid is a triangular diagram that shows an ecosystem's loss of energy, which results as
energy passes through the ecosystem's food chain.
 Each layer in the energy pyramid represents one trophic level.
 Producers form the pyramid's base, which is the lowest trophic level. The lowest level has the most
energy in the pyramid.
 Herbivores have less energy and make up the second level. Carnivores that feed on herbivores make
up the higher level.
5

The energy stored by the organisms at each trophic level is about one tenth the energy stored by the
organisms in the level below. So, the diagram takes the shape of a pyramid.
 Big predators, such as lions, are rare compared to herbivores.
 Big predators are rare because a lot more energy is required to support a single predator than a
single herbivore. Many ecosystems do not have enough energy to support a large population of
predators.
WATER CYCLE
> The water cycle continuously moves water between the atmosphere, the land, and the oceans.
 Water vapor condenses and falls to Earth's surface as precipitation.
 Some of this water percolates into the soil and becomes groundwater.
 Other water runs across the surface of Earth into rivers, lakes, and oceans.
 Then, the water is heated by the sun and reenters the atmosphere by evaporation.
 Water also evaporates from trees and plants in a process called transpiration.
CARBON AND OXYGEN CYCLES
> Animals, plants, and other photosynthesizing organisms play an important role in cycling carbon and
oxygen through an ecosystem.
 Carbon and oxygen are critical for life on Earth, and their cycles are tied closely together.
 The carbon cycle is the continuous movement of carbon from the nonliving environment into living
things and back.
 Plants use the carbon dioxide, CO2, in air to build organic molecules during the process of
photosynthesis. During photosynthesis, oxygen is released into the surroundings.
 Many organisms, such as animals, use this oxygen to help break down organic molecules (respiration),
which releases energy and CO2. Plants can use the CO2 in photosynthesis.
 Respiration is the process of taking in oxygen, breaking down organic molecules for energy and
releasing CO2 into the surroundings.
 Carbon is also released into the atmosphere in the process of combustion. Combustion is the burning of
a substance.
 Fossil fuels are formed from the remains of dead plants and animals, which are made of carbon. The
burning of fossil fuels releases carbon dioxide into the atmosphere.
 Humans burn fossil fuels, such as oil, gasoline, coal, and natural gas, to generate electricity and to
power vehicles.
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6.1g Relationships between organisms may be negative, neutral, or positive. Some organisms may interact with
one another in several ways. They may be in a producer/consumer, predator/prey, or parasite/host relationship;
or one organism may cause disease in, scavenge, or decompose another.
PREDATOR-PREY INTERACTIONS
> Species that involve predator-prey or parasite-host relationships often develop adaptations in response to
one another.
 One of the most common interactions in communities is that between predators and their prey.
Predation is the act of one organism killing another for food.
 In parasitism, one organism feeds on another organism called a host.
 The host is almost always larger than the parasite and is usually harmed but not killed.
 Parasites often live on or in their host. Therefore, the parasite depends on its host not only for food
but for a place to live as well.
 Hosts try to keep parasites from infecting them. Hosts can defend themselves with their immune
systems or behaviors such as scratching.
In response, parasites may evolve ways to overcome the host's defenses.
 Herbivores are animals that eat plants.
 Unlike predators, herbivores do not often kill the plants. But plants do try to defend themselves.
 Plants defend themselves from herbivores with thorns and spines or with bad tasting chemical
compounds. These chemical compounds may even cause sickness or death.
 Some herbivores have evolved ways to overcome plant defenses.
OTHER INTERACTIONS
> Mutualism and commensalism are two kinds of symbiotic relationships in which at least one species
benefits.
 Not all interactions between organisms result in a winner and a loser.
 Symbiosis is a relationship in which two species live in close association with each other.
 — In some forms of symbiosis, a species may benefit from the relationship.
 A relationship between two species in which both species benefit is called mutualism.
 In commensalism, two species have a relationship in which one species benefits and the other is
neither harmed nor helped.
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PERFORMANCE INDICATOR 6.3
Explain how the living and nonliving environments change over time and respond to disturbances.
6.3a The interrelationships and interdependencies of organisms affect the development of stable ecosystems.
6.3b Through ecological succession, all ecosystems progress through a sequence of changes during which one
ecological community modifies the environment, making it more suitable for another community. These longterm gradual changes result in the community reaching a point of stability that can last for hundreds or
thousands of years.
6.3c A stable ecosystem can be altered, either rapidly or slowly, through the activities of organisms (including
humans), or through climatic changes or natural disasters. The altered ecosystem can usually recover through
gradual changes back to a point of long-term stability.
SUCCESSION
> An ecosystem responds to change in such a way that the ecosystem is restored to equilibrium.
 The replacement of one kind of community by another at a single place over a period of time is called
succession.
 The first organisms to appear in a newly made habitat are often called pioneer species. They change the
habitat in such a way that other species can live in the ecosystem.
 Often, the new species will replace the pioneer species.
For example, when a tree falls down in a rain forest, the newly vacant patch proceeds through
succession until the patch returns to its original state.
— Sometimes, the ecosystem will find an equilibrium in which different species dominate after a
change.
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fossil fuel a nonrenewable energy resource formed from the remains of organisms that lived long ago; examples
include oil, coal, and natural gas
acid rain precipitation that has a pH below normal and has an unusually high concentration of sulfuric or nitric
acids, often as a result of chemical pollution of the air from sources such as automobile exhausts and the
burning of fossil fuels
global warming a gradual increase in the average global temperature
greenhouse effect the warming of the surface and lower atmosphere of Earth that occurs when carbon dioxide,
water vapor, and other gases in the air absorb and reradiate infrared radiation
erosion a process in which the materials of Earth's surface are loosened, dissolved, or worn away and
transported from one place to another by a natural agent, such as wind, water, ice, or gravity
deforestation the process of clearing forests
biodiversity the variety of organisms in a given area, the genetic variation within a population, the variety of
species in a community, or the variety of communities in an ecosystem
extinction the death of every member of a species
recycling the process of recovering valuable or useful materials from waste or scrap
Key Idea 7:
Human decisions and activities have had a profound impact on the physical and living environment.
Population growth has placed new strains on the environment—massive pollution of air and water,
deforestation and extinction of species, global warming, and alteration of the ozone shield. Some individuals
believe that there will be a technological fix for such problems. Others, concerned with the accelerating pace of
change and the ecological concept of finite resources, are far less optimistic. What is certain, however, is that
resolving these issues will require increasing global awareness, cooperation, and action.
PERFORMANCE INDICATOR 7.1
Describe the range of interrelationships of humans with the living and nonliving environment.
7.1a The Earth has finite resources; increasing human consumption of resources places stress on the natural
processes that renew some resources and deplete those resources that cannot be renewed.
7.1b Natural ecosystems provide an array of basic processes that affect humans. Those processes include but are
not limited to: maintenance of the quality of the atmosphere, generation of soils, control of the water cycle,
removal of wastes, energy flow, and recycling of nutrients. Humans are changing many of these basic processes
and the changes may be detrimental.
7.1c Human beings are part of the Earth’s ecosystems. Human activities can, deliberately or inadvertently, alter
the equilibrium in ecosystems. Humans modify ecosystems as a result of population growth, consumption, and
technology. Human destruction of habitats through direct harvesting, pollution, atmospheric changes, and other
factors is threatening current global stability, and if not addressed, ecosystems may be irreversibly affected.
PERFORMANCE INDICATOR 7.2
Explain the impact of technological development and growth in the human population on the living and
nonliving environment.
7.2a Human activities that degrade ecosystems result in a loss of diversity of the living and nonliving
environment. For example, the influence of humans on other organisms occurs through land use and pollution.
Land use decreases the space and resources available to other species, and pollution changes the chemical
composition of air, soil, and water.
7.2b When humans alter ecosystems either by adding or removing specific organisms, serious consequences
may result. For example, planting large expanses of one crop reduces the biodiversity of the area.
7.2c Industrialization brings an increased demand for and use of energy and other resources including fossil and
nuclear fuels. This usage can have positive and negative effects on humans and ecosystems.
9
HUMANS AND THE ENVIRONMENT
> Humans are a part of the environment and can affect the resilience of the environment.
 Humans now live in almost every kind of ecosystem on Earth.
 As human population increases, the impact of humans on the environment increases.
— The more that the human population grows, the more resources from the environment we will need to
survive.
 Earth is an interconnected planet: we depend on the environment, and the environment is affected by
our actions.
 Learning about this connectedness helps us care for the environment and ensures that the environment
will continue to support us and other species on Earth.
RESOURCES
> Renewable resources are natural resources that can be replaced at the same rate at which they are
consumed. Nonrenewable resources are resources that form at a rate that is much slower than the rate at
which they are consumed.
 Earth's resources are described as renewable or nonrenewable.
 A renewable resource's supply is either so large or so constantly renewed that it will never be used up.
 However, a resource can be renewable but still be used up if it is used faster than it can be renewed.
 Most of our energy today comes from fossil fuels. Fossil fuels are nonrenewable energy resources that
formed from the remains of organisms that lived long ago.
 Fossil fuels such as coal, oil, and natural gas, are nonrenewable resources because it takes millions of
years for them to form.
 We use fossil fuels at a rate that is faster than the rate at which they form. So, when these resources are
gone, millions of years will pass before more have formed.
ECOSYSTEM DISRUPTION
> Ecosystem disruptions can result in loss of biodiversity, food supplies, potential cures for diseases, and the
balance of ecosystems that supports all life on Earth.
 We cannot avoid disrupting ecosystems as we try to meet the needs of a growing human population.
 We can learn about how our actions affect the environment so that we can create ways to conserve it.
 Over the last 50 years, about half of the world's tropical rain forests have been cut down or burned for
timber, pastureland, or farmland.
— This process of clearing forests is called deforestation.
— The problem with deforestation is that as the rain forests and other habitats disappear, so do their
inhabitants.
 Habitat destruction and damage cause more extinction and loss of biodiversity than any other human
activities do.
 Ecosystem disruption decreases the number of Earth's species.
 Biodiversity affects the stability of ecosystems and the sustainability of populations. Biodiversity is the
variety of organisms in a given area.
Every species plays an important role in the cycling of energy and nutrients in an ecosystem. Each
species either depends on or is depended on by at least one other species.
When a species disappears, a strand in a food web disappears. If a keystone species disappears, other
species may also disappear.
 Humans have disrupted ecosystems by intentionally and unintentionally introducing nonnative species.
 Many species are on the edge of extinction. Extinction is the death of every member of a species.
AIR POLLUTION
> Air pollution causes respiratory problems for people, results in acid rain, damages the ozone layer, and may
affect global temperature.
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
Acid rain is precipitation that has an unusually high concentration of sulfuric or nitric acids, which is
caused by pollution.
 Acid rain damages forests and lakes.
 The ozone layer protects life on Earth from the sun's damaging ultraviolet (UV) rays.
 The ozone layer has been damaged by chlorofluorocarbons (CFCs).
— CFCs are human-made chemicals that are used as coolants in refrigerators and air conditioners and
as propellants in spray cans.
GLOBAL WARMING
> Burning fossil fuels increases the amount of CO2 in the atmosphere. Increases in atmospheric CO2 may be
responsible for an increase in global temperatures.
 Global warming is the gradual increase in the average global temperature.
 The greenhouse effect is the warming of the surface and lower atmosphere of Earth that happens when
greenhouse gases in the air absorb and reradiate heat.
— Examples of greenhouse gases are CO2 and water vapor.
— The greenhouse effect is necessary to keep Earth's temperatures stable.
 Earth's global temperatures have been rising steadily for many decades.
 Most scientists think this increase in temperatures is caused by an increase in CO2.
 A continued increase in global temperatures has the potential to cause a number of serious
environmental problems.
 Possible damage from global warming includes melting ice sheets, sea level rise, destruction of coastal
ecosystems, and changes in weather patterns.
WATER POLLUTION
> Water pollution can come from fertilizers and pesticides used in agriculture, livestock farms, industrial
waste, oil runoff from roads, septic tanks, and unlined landfills.
 Pollution enters groundwater when polluted surface water percolates down through the soil.
 Landfills and leaking underground septic tanks are also major sources of groundwater pollution.
 When pollutants run off land and into rivers, both aquatic habitats and public water sources may be
contaminated.
 Fertilizers from farms, lawns, and golf courses can run off into a body of water, which increases the
amount of nutrients in the water leading to an excessive growth of algae.
 Algal blooms can deplete the dissolved oxygen in a body of water. Fish and other organisms then
suffocate in the oxygen-depleted water.
SOIL DAMAGE
> Soil erosion destroys fertile soil that we need in order to produce food.
 Fertile soil forms from rock that is broken down by weathering.
 Nutrients that make soil fertile come from the weathered rock as well as from bacteria, fungi and the
remains of plants and animals.
 The processes that form just a few centimeters of fertile soil can take thousands of years.
 The greatest threat to soil is erosion. Erosion is a process in which the materials of Earth's surface are
worn away and transported from one place to another by wind, gravity, or water.
— Many farming methods can lead to soil erosion by loosening the topsoil and removing plants that
hold the soil in place. The topsoil can then be washed away by wind or rain.
 Sustainable agricultural practices can prevent erosion.
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PERFORMANCE INDICATOR 7.3
Explain how individual choices and societal actions can contribute to improving the environment.
7.3a Societies must decide on proposals which involve the introduction of new technologies. Individuals need to
make decisions which will assess risks, costs, benefits, and trade-offs.
7.3b The decisions of one generation both provide and limit the range of possibilities open to the next
generation.
CONSERVATION AND RESTORATION
> Conservation involves protecting existing natural habitats. Restoration involves cleaning up and restoring
damaged habitats.
 Conservation and restoration are two major techniques for dealing with environmental problems.
 Conserving habitats prevents environmental issues that arise from ecosystem disruption.
 Restoration reverses damage to ecosystems.
 The best way to deal with environmental problems is to prevent them from happening.
REDUCE RESOURCE USE
> We can reduce our use of resources, such as water and fossil fuels for energy. We can reuse goods rather
than disposing of them. Furthermore, we can recycle waste to help protect the environment.
 One of the best ways that you can help solve environmental problems is by reducing the amount of
energy that you use and the amount of waste that you produce.
 The reuse of goods saves both money and resources.
 The process of reusing things instead of taking more resources from the environment is called
recycling.
— Recycling existing products generally costs less than making new ones from raw materials does.
TECHNOLOGY
> Research and technology can help protect our environment by providing cleaner energy sources, better ways
to deal with waste, and improved methods for cleaning up pollution.
 Researchers must determine the cause of an environmental problem before they can provide a solution
to it.
 Scientists make observations and collect data. After analyzing the data, a scientist may propose a
solution to the environmental problem that was studied.
 Proposals should take into account the costs, risks, and benefits of implementing the solution.
ENVIRONMENTAL AWARENESS
> Education makes people more aware of environmental issues. Education also shows people how they can
help address such issues. Expressing support, or advocating, for efforts to protect the environment can help
get more people involved in these efforts.
 Many environmental problems have been solved because of the efforts of those who advocate for a
solution.
 Educating the public about the environment helps gain public support for solving environmental issues.
PLANNING FOR THE FUTURE
> Careful planning for the future can help us avoid damaging the environment and can help us solve the
environmental issues that we face.
 If we want a safe, healthy, bright future, we need to actively aim for it.
 Society can plan by noting the effects of certain activities, such as development and resource use.
 After analyzing risks, costs, and benefits to the community, the government may choose to enforce
limitations on the development.
 When governments plan for the future, they can protect resources for the community for years to come.
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