Download Section 1: What Is an Ecosystem? Preview • Bellringer • Key Ideas

•Preview
Section 1: What Is an Ecosystem?
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Bellringer
Key Ideas
Ecosystems
Succession
Major Biological Communities
Terrestrial Biomes
Aquatic Ecosystems
Summary
•After Bellringer
looking at an aquarium, list all the organisms you see. When you are finished
make a list of all the factors that affect the survival of the organisms in the aquarium.
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Key Ideas
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What are the parts of an ecosystem?
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How does an ecosystem respond to change?
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What two key factors of climate determine a biome?
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What are the three major groups of terrestrial biomes?
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What are the four kinds of aquatic ecosystems?
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Ecosystems
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.
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An ecosystem includes a community of organisms and their physical environment.
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Ecosystems, continued
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A community of organisms is a web of relationships.
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.
Visual Concept: Comparing Biotic and Abiotic Factors
Ecosystems, continued
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.
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Ecosystems with high biodiversity are often more able to resist damage.
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Ecosystems, continued
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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.
Succession
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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.
Visual Concept: Pioneer Species
Succession, continued
An ecosystem responds to change in such a way that the ecosystem is restored to
equilibrium.
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.
Ecological Succession at Glacier Bay
Major Biological Communities
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.
Major Biological Communities, continued
Two key factors of climate that determine biomes are temperature and
precipitation.
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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.
Terrestrial Biomes
Earth’s major terrestrial biomes can be grouped by latitude. Latitude affects the
amount of solar energy that a biome receives and thus affects a biome’s
temperature range.
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Tropical biomes are generally near the equator.
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For the most part, temperate biomes are between 30° and 60° latitude.
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High-latitude biomes are at latitudes 60° and higher.
• Earth’s Major biomes
•Tropical
Terrestrial Biomes, continued
Biomes
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Because they are located at low latitudes near the equator, all tropical biomes are
warm.
Tropical rain forests receive large amounts of rain and are warm all year. They
have the greatest biodiversity of any land biome.
Savannas are tropical grasslands that have long dry seasons and shorter wet
seasons.
Tropical deserts get very little rain. Because deserts are drier, they have fewer
plants and animals than other biomes.
•Temperate
Terrestrial Biomes, continued
Biomes
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Biomes at mid-latitudes have a wide range of temperatures throughout the year.
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Temperate grasslands have moderate precipitation and cooler temperatures than
savannas do. Temperate grasslands are often used for agriculture.
Temperate forests grow in mild climates that receive plenty of rain.
Temperate deserts receive little precipitation, but have a wide temperature range
throughout the year.
•High-Latitude
Terrestrial Biomes, continued
Biomes
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Biomes at high latitudes have cold temperatures.
Coniferous forests in cold, wet climates are called taiga. Winters are long and cold.
Most of the precipitation falls in the summer.
The tundra gets very little rain, so plants are short. Much of the water in the soil is
not available because the water is frozen for most of the year.
Elements of Climate
Aquatic Ecosystems
Aquatic ecosystems are organized into freshwater ecosystems, wetlands,
estuaries, and marine ecosystems.
Freshwater ecosystems are located in bodies of fresh water, such as lakes, ponds,
and rivers. These ecosystems have a variety of plants, fish, arthropods, mollusks,
and other invertebrates.
Wetlands provide a link between the land and fully aquatic habitats. Water-loving
plants dominate wetlands. Wetlands moderate flooding and clean the water that
flows through them.
Aquatic Ecosystems, continued
An estuary is an area where fresh water from a river mixes with salt water from an
ocean. Estuaries are productive ecosystems because they constantly receive fresh
nutrients from the river and the ocean.
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Marine ecosystems are found in the salty waters of the oceans. Kelp forests,
seagrass communities, and coral reefs are found near land. The open ocean, far
from land, has plankton and large predators, such as dolphins, whales, and sharks.
Summary
An ecosystem is a community of organisms and their abiotic environment.
An ecosystem responds to change in such a way that the ecosystem is restored to
equilibrium.
Two key factors of climate that determine biomes are temperature and
precipitation.
Summary, continued
Earth’s major terrestrial biomes can be grouped by latitude into tropical, temperate
biomes, and high latitude.
Aquatic ecosystems are organized into freshwater ecosystems, wetlands,
estuaries, and marine ecosystems.
•Preview
Section 2: Energy Flow in Ecosystems
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Bellringer
Key Ideas
Trophic Levels
Loss of Energy
Summary
•ThinkBellringer
about your local area and make a diagram of a food chain that would be typical
for your area. Try to put six organisms into the food chain.
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Key Ideas
How does energy flow through an ecosystem?
What happens to energy as it is transferred between trophic levels in a
community?
Trophic Levels
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.
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Visual Concept: Comparing Consumers and Producers
Trophic Levels, continued
Decomposers, such as bacteria and fungi, are organisms that break down the
remains of animals.
In an ecosystem, energy flows from the sun to producers to consumers to
decomposers.
Each step in the transfer of energy through an ecosystem is called a trophic level.
Trophic Levels
Trophic Levels, continued
Food Chains
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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. Cows are an example of an herbivore.
Trophic Levels, continued
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.
Visual Concept: Types of Consumers
•FoodTrophic
Levels, continued
Webs
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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.
• Food Chain and Food Web in Antarctic Ecosystem
•EnergyLossPyramid
of Energy
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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.
Energy Transfer Through Trophic Levels
Loss of Energy, continued
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.
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Each layer in the energy pyramid represents one trophic level.
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Loss of Energy, continued
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Producers form the pyramid’s base, which is the lowest trophic level. The lowest
level has the most energy in the pyramid.
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Herbivores have less energy and make up the second level.
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Carnivores that feed on herbivores make up the higher level.
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Visual Concept: Energy Pyramid
Energy Loss, continued
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.
Amount of Energy at Four Trophic Levels
Summary
In an ecosystem, energy flows from the sun to producers to consumers to
decomposers.
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.
•Preview
Section 3: Cycling of Matter
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Bellringer
Key Ideas
Water Cycle
Carbon and Oxygen Cycles
Nitrogen Cycle
Phosphorus Cycle
Summary
•MakeBellringer
a list of anything you have used in the last week that had been previously
recycled, or was made of recycled materials. After you have made your list, discuss
what the item is recycled from, if known, and the advantages or disadvantages of
recycling each item.
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Key Ideas
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What is the water cycle?
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Why are plants and animals important for carbon and oxygen in an ecosystem?
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Why must nitrogen cycle through an ecosystem?
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Why must phosphorus cycle through an ecosystem?
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Water Cycle
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The water cycle continuously moves water between the atmosphere, the land, and
the oceans.
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Water vapor condenses and falls to Earth’s surface as precipitation.
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Some of this water percolates into the soil and becomes groundwater.
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Water Cycle, continued
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Other water runs across the surface of Earth into rivers, lakes, and oceans.
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Then, the water is heated by the sun and reenters the atmosphere by evaporation.
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Water also evaporates from trees and plants in a process called transpiration.
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Visual Concept: Water Cycle
Carbon and Oxygen Cycles
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.
Animals, plants, and other photosynthesizing organisms play an important role in
cycling carbon and oxygen through an ecosystem.
Carbon and Oxygen Cycles, continued
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, which releases energy and CO2. Plants can use the CO2 in
photosynthesis.
Respiration is the process of exchanging oxygen and CO2 between organisms
and their surroundings.
Carbon and Oxygen Cycles, continued
Carbon is also released into the atmosphere in the process of combustion.
Combustion is the burning of a substance.
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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 and coal, to generate electricity and to power
vehicles.
Visual Concept: Carbon Cycle
Nitrogen Cycle
Nitrogen must be cycled through an ecosystem so that the nitrogen is available for
organisms to make proteins.
The nitrogen cycle is the process in which nitrogen circulates among the air, soil,
water, and organisms in an ecosystem.
The atmosphere is about 78% nitrogen gas, N2. But most organisms cannot use
nitrogen gas. It must be changed into a different form.
Nitrogen Cycle, continued
In a process called nitrogen fixation, bacteria convert nitrogen gas, N2, into
ammonia, NH3.
Nitrogen-fixing bacteria live in the soil and on the roots of some plants. Nitrogen
may also be fixed by lightning.
Nitrogen is also fixed when humans burn fuels in vehicles and industrial plants.
Nitrogen Cycle, continued
Assimilation is the process in which plants absorb nitrogen. When an animal eats a
plant, nitrogen compounds become part of the animal’s body.
During ammonification, nitrogen from animal waste or decaying bodies is returned
to the soil by bacteria.
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During nitrification, ammonia, NH3, is converted to nitrite and then nitrate.
During denitrification, nitrate, NO3, is changed to nitrogen gas, N2, which returns
to the atmosphere.
Visual Concept: Nitrogen Cycle
Phosphorus Cycle
Like water, carbon, oxygen, and nitrogen, phosphorus must be cycled in order for
an ecosystem to support life.
The phosphorus cycle is the movement of phosphorus in different chemical forms
from the surroundings to organisms and then back to the surroundings.
Phosphorus Cycle, continued
Phosphorus is often found in soil and rock as calcium phosphate, which dissolves
in water to form phosphate.
The roots of plants absorb phosphate. Humans and animals that eat the plants
reuse the organic phosphorus.
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When the humans and animals die, phosphorus is returned to the soil.
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Summary
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The water cycle is the continuous movement of water between the atmosphere,
the land, and the oceans.
Animals, plants, and other photosynthesizing organisms play an important role in
cycling carbon and oxygen through an ecosystem.
Nitrogen must be cycled through an ecosystem so that the nitrogen is available for
organisms to make proteins.
Like water, carbon, oxygen, and nitrogen, phosphorus must be cycled in order for
an ecosystem to support life.
Section 4: Populations
Key Ideas
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Why is it important to study populations?
What is the difference between exponential growth and logistic
growth?
What factors affect population size?
How have science and technology affected human population
growth?
What Is a Population?
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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.
Understanding population growth is important because populations of
different species interact and affect one another, including human
populations.
Population Growth
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Whether a population grows or shrinks depends on births, deaths,
immigration, and emigration.
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Immigration is the movement of individuals into a population.
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Emigration is the movement of individuals out of a population.
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A simple population model describes the rate of population growth as
the difference between birthrate, death rate, immigration, and
emigration.
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Plotting population changes against time on a graph creates a model
in the form of a curve.
Two major models of population growth are exponential growth and
logistic growth.
Exponential growth occurs when numbers increase by a certain
factor in each successive time period. This type of increase causes
the J-shaped curve of exponential growth.
In exponential growth, population size grows slowly when it is small.
But as the population gets larger, growth speeds up.
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.
Density-dependent factors are variables affected by the number of
organisms present in a given area.
Density independent factors are variables that affect a population
regardless of the population density. Examples of densityindependent factors are weather, floods, and fires.
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.
When a population is small, the growth rate is fast because there are
plenty of resources.
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As the population approaches the carrying capacity, resources
become scarce.
Competition for food, shelter, and mates increases between
individuals of a population. As a result, the rate of growth slows.
The population eventually stops growing when the death rate equals
the birthrate.
On a graph, logistic growth is characterized by an S-shaped curve.
Factors That Affect Population Size
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Most populations increase or decrease. Some change with the
seasons. Others have good years and bad years.
Many factors cause populations to grow and shrink. 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 are often density dependent because they can have a
stronger influence when crowding exists. As the density of a
population increases, the effects of starvation, predators, and
disease often also increase.
Humans affect populations of many species. Most of the time,
humans cause populations to drop by disrupting habitats, introducing
diseases, or introducing nonnative species.
Human Population
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Today, the world population is more than 6 billion people and is
increasing.
Better sanitation and hygiene, disease control, and agricultural
technology are a few ways that science and technology have
decreased the death rate of the human population.
As more humans live on the planet, more resources will be needed to
support them. As demand for resources increases, more pressure
will be put on Earth’s ecosystems.
For most of human history, there have been fewer than 10 million
people.
Two thousand years ago, there were only 300 million people. Around
the time of the Industrial Revolution, the human population started to
accelerate rapidly.
Human population began accelerating exponentially starting in the
late 1700s. Now, there are more than 6 billion people, and some
scientists think that the population will grow to 9 billion in 50 years.
Science and technology are major reasons why the human
population is growing so rapidly.
Advances in agricultural technology have allowed efficient production
of crops and other foods. More food supports more people.
Medical advances have also allowed the human population to
increase. Vaccines have lowered the death rate. Other medical
advances have allowed adults to live longer lives.
Summary
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Understanding population growth is important because populations of
different species interact and affect one another, including human
populations.
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.
Water, food, predators, and human activity are a few of many factors
that affect the size of a population.
Better sanitation and hygiene, disease control, and agricultural
technology are a few ways that science and technology have
decreased the death rate of the human population.
•Preview
Section 5: Interactions In Communities
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Bellringer
Key Ideas
Predator-Prey Interactions
Other Interactions
Summary
•Animals,
Bellringer
like people, live in communities. Make a list of different jobs that are done by
people in your community that keep the community running. Keep in mind that some
people may have more than one function in a community.
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Key Ideas
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How do predator-prey interactions influence both predators and prey?
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What are two other types of interaction in a community?
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Predator-Prey Interactions
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.
Species that involve predator-prey or parasite-host relationships often develop
adaptations in response to one another.
Back-and-forth evolutionary adjustment between two species that interact is called
coevolution.
Predator-Prey Interactions, continued
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.
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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.
Predator-Prey Interactions, continued
Hosts try to keep parasites from infecting them. Hosts can defend themselves with
their immune systems or behaviors such as scratching.
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In response, parasites may evolve ways to overcome the host’s defenses.
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Predator-Prey Interactions, continued
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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.
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Some herbivores have evolved ways to overcome plant defenses.
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Other Interactions
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Not all interactions between organisms result in a winner and a loser.
Symbiosis is a relationship in which two species that live in close association with
each other. In some forms of symbiosis, a species may benefit from the
relationship.
Mutualism and commensalism are two kinds of symbiotic relationships in which at
least one species benefits.
Other Interactions, continued
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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.
Summary
Species that involve predator-prey or parasite-host relationships often develop
adaptations in response to one another.
Mutualism and commensalism are two types of symbiotic relationships in which
one or both of the species benefit.
Section 6: Shaping Communities
Key Ideas
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How does a species’ niche affect other organisms?
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How does competition for resources affect species in a community?
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What factors influence the resiliency of an ecosystem?
Carving a Niche
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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.
A niche includes the role that the organism plays in the community.
This role affects the other organisms in the community.
Competing for Resources
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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.
Competition for resources between species shapes a species’
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.
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Competition has several possible outcomes.
Sometimes, one species wins, and the other loses. The loser is
eliminated from the habitat.
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.
Ecosystem Resiliency
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Ecosystems can be destroyed or damaged by severe weather,
humans, or introduced species. Other factors can help keep an
ecosystem stable.
Interactions between organisms and the number of species in an
ecosystem add to the resiliency of an ecosystem.
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Higher biodiversity often helps make an ecosystem more resilient.
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Predation can reduce the effects of competition among species.
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Predators can influence more than their prey. When predators eat
one species, they may reduce competition among other species.
A keystone species is a species that is critical to an ecosystem
because the species affects the survival and number of many other
species in its community.
Summary
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A niche includes the role that the organism plays in the community.
This role affects the other organisms in the community.
Competition for resources between species shapes a species’
fundamental niche.
Interactions between organisms and the number of species in an
ecosystem add to the stability of an ecosystem.
• Section 7: An Interconnected
Planet
Preview
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Bellringer
Key Ideas
Humans and the Environment
Resources
The Environment and Health
Summary
• Bellringer
List examples of chemical pollution from
industry, agriculture, or everyday use. What
are some possible effects that these
pollutants can have on the environment?
• Key Ideas
• How are humans and the environment
connected?
• What is the difference between
renewable resources and nonrenewable
resources?
• How can the state of the environment
affect a person’s health and quality of
life?
• Humans and 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.
• Humans are a part of the environment
and can affect the resilience of the
environment. The more that the human
population grows, the more resources
from the environment we will need to
survive.
• Humans and the Environment,
continued
• 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
• Earth’s resources are described as
renewable or nonrenewable.
• Renewable resources are natural
resources that can be replaced at the
same rate at which they are consumed.
• 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.
• Resources, continued
• Nonrenewable resources are resources
that form at a rate that is much slower
than the rate at which they are
consumed.
• 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.
• Resources, continued
• 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.
• The Environment and Health
• Our health and quality of life are affected
by the state of the environment.
• Pollution and habitat destruction destroy
the resources we need to live, such as
the air we breathe, the water we drink,
and the food we eat.
• Summary
• Humans are a part of the environment
and can affect the resilience of the
environment.
• 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.
• Pollution and habitat destruction destroy
the resources we need to live, such as
the air we breathe, the water we drink,
and the food we eat.
•Preview
Section 8: Environmental Issues
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Bellringer
Key Ideas
Air Pollution
Global Warming
Water Pollution
Soil Damage
Ecosystem Disruption
Summary
•Brainstorm
Bellringer
examples of solid, liquid, and gaseous pollutants in the environment.
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Key Ideas
What are the effects of air pollution?
How might burning fossil fuels lead to climate change?
What are some sources of water pollution?
Why is soil erosion a problem?
How does ecosystem disruption affect humans?
Air Pollution
Air pollution causes respiratory problems for people, results in acid rain, damages
the ozone layer, and may affect global temperature.
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.
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Air Pollution, continued
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.
Ozone “Hole” Over Antarctica
Global Warming
Global temperature may be affected by air pollutants. 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.
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The greenhouse effect is necessary to keep Earth’s temperatures stable.
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Global Warming, continued
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However, Earth’s global temperatures have been rising steadily for many decades.
Most scientists think that this increase in temperatures is caused by an increase in
CO2.
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, continued
A continued increase in global temperatures has the potential to cause a number
of serious environmental problems.
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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.
Water Pollution, continued
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.
Water Pollution
Soil Damage
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Fertile soil allows agriculture to supply the world with food.
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Fertile soil forms from rock that is broken down by weathering.
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Nutrients that make soil fertile come from the weathered rock as well as from
bacteria, fungi and the remains of plants and animals.
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The processes that form just a few centimeters of fertile soil can take thousands of
years.
Soil Damage, continued
The greatest threat to soil is soil 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.
Soil erosion destroys fertile soil that we need in order to produce food. Roots from
plants and trees help hold soil together and protect it from erosion.
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.
Soil Damage, continued
Sustainable agricultural practices can prevent erosion
Terracing changes a steep field into a series of flat steps that stop gravity from
eroding the soil.
Planting a cover crop, such as soybeans, restores nutrients to the soil.
Crop rotation, or planting a different crop every year, slows down the depletion of
nutrients in the soil.
In contour plowing, rows are plowed in curves along hills instead of in straight
lines. The rows then act as a series of dams, which prevent water from eroding the
soil.
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.
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We can learn about how our actions affect the environment so that we can create
ways to conserve it.
Ecosystem Disruptions, continued
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 Disruptions, continued
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.
Ecosystem Disruptions, continued
When a species disappears, a strand in a food web disappears. If a keystone
species disappears, other species may also disappear.
There are many ways in which humans benefit from a variety of life forms on Earth.
Humans have used a variety of organisms on Earth for food, clothing, shelter, and
medicine.
Ecosystem Disruptions, continued
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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.
Summary
Air pollution causes respiratory problems for people, results in acid rain, damages
the ozone layer, and affects global temperature.
Burning fossil fuels increases the amount of CO2 in the atmosphere. Increases in
atmospheric CO2 may be responsible for an increase in global temperatures.
Water pollution can come from fertilizers and pesticides used in agriculture and
from livestock farms, industrial waste, oil runoff from roads, septic tanks, and
unlined landfills.
Summary, continued
Soil erosion destroys fertile soil that we need in order to produce food.
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.
• Section 9: Environmental Solutions
Preview
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Bellringer
Key Ideas
Conservation and Restoration
Reducing Resource Use
Technology
Environmental Awareness
Planning for the Future
Summary
• Bellringer
Write 3 to 4 sentences describing a global,
national, or local environmental problem
you have heard about and any efforts that
are being undertaken to correct the
problem.
• Key Ideas
• How do conservation and restoration
solve environmental issues?
• What are three ways that people can
reduce the use of environmental
resources?
• How can research and technology affect
the environment?
• Key Ideas, continued
• How do education and advocacy play a
part in preserving the environment?
• Why is it important for societies to
consider environmental impact when
planning for the future?
• Conservation and Restoration
• Two major techniques for dealing with
environmental problems are
conservation and restoration.
• Conservation involves protecting existing
natural habitats.
• Restoration involves cleaning up and
restoring damaged habitats.
• The best way to deal with environmental
problems is to prevent them from
happening. Conserving habitats prevents
environmental issues that arise from
ecosystem disruption.
• 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.
• Reduce Resource Use, continued
• 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.
• Technology, continued
• 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.
• Environmental Awareness,
continued
• Many environmental problems have been
solved because of the efforts of those
who advocate for a solution.
• Conservation groups make efforts to
educate people, protect land, and
influence laws through advocacy.
• Environmental Awareness,
continued
• Some organizations work on an
international level. Others work on local
environmental problems.
• Some groups help farmers, ranchers,
and other landowners ensure the longterm conservation of their land.
• Individuals and the media also play an
important role in raising awareness of
environmental issues.
• Environmental Awareness,
continued
• Educating the public about the
environment helps gain public support for
solving environmental issues.
• Environmental education can enrich
people’s experience of their world and
empower them to care for it.
• Ecotourism is one way to educate the
public about the environment.
Ecotourism is a form of tourism that
supports conservation of the
environment.
• Often, an ecotourist is given an
opportunity to help solve environmental
problems as part of his or her tour.
• 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.
• Planning for the Future, continued
• 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.
• Summary
• Conservation involves protecting existing
natural habitats. Restoration involves
cleaning up and restoring damaged
habitats.
• We can reduce our use of natural
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.
• 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.
• Summary, continued
• Education makes people more aware of
environmental issues and of ways that
they can help. Expressing support, or
advocating, for efforts to protect the
environment can help get more people
involved.
• Careful planning for the future can help
us avoid damaging the environment and
solve environmental issues that we
currently face.