slide 1 of 21 3-1 what is ecology? copyright pearson prentice hall

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3-1 What Is Ecology?

Copyright Pearson Prentice Hall

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Interactions and Interdependence

Interactions and InterdependenceEcology is the scientific study of interactions among

organisms and between organisms and their environment, or surroundings.


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The biosphere contains the combined portions of the planet in which all of life exists, including:

• land• water• air, or atmosphere

The biosphere extends from about 8 kilometers above Earth's surface to as far as 11 kilometers below the surface of the ocean.


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Interactions within the biosphere produce a web of interdependence between organisms and the environment in which they live.

The interdependence of life on Earth contributes to an ever-changing, or dynamic, biosphere.


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Levels of Organization

What different levels of organization do ecologists study?


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To understand relationships within the biosphere, ecologists ask questions about events and organisms that range in complexity from a single individual to the entire biosphere.

The levels of organization that ecologists study include: individuals, populations, communities, ecosystems, and biomes.


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Ecosystem

Community

Population

Individual

Biome

Biosphere

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A species is a group of organisms so similar to one another that they can breed and produce fertile offspring.Populations are groups of individuals that belong to the same species and live in the same area.Communities are assemblages of different populations that live together in a defined area.


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An ecosystem is a collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment.A biome is a group of ecosystems that have the same climate and similar dominant communities.The highest level of organization that ecologists study is the entire biosphere itself.


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Ecological Methods

What methods are used to study ecology?


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Ecological Methods

Ecological MethodsRegardless of the tools they use, scientists conduct modern ecological research using three basic approaches:

• observing• experimenting• modeling

All of these approaches rely on the application of scientific methods to guide ecological inquiry.


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Ecological MethodsObserving

Observing is often the first step in asking ecological questions.

Some observations are simple. Others are complex and may form the first step in designing experiments and models.


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Ecological Methods

ExperimentingExperiments can be used to test hypotheses.An ecologist may set up an artificial environment in a

laboratory to imitate and manipulate conditions that organisms would encounter in the wild.

Other experiments are conducted within natural ecosystems.


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Ecological Methods

ModelingEcologists make models to gain insight into complex

phenomena.Many ecological models consist of mathematical

formulas based on data collected through observation and experimentation.

The predictions made by ecological models are often tested by further observations and experiments.


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3-1

The combined portions of the planet in which life exists, including land, water, and the atmosphere, form the

• biosphere.• community.• species.• ecosystem.


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3-1

A group of organisms that can breed and produce fertile offspring is known as a(an)

• ecosystem.• species.• biome.• community.


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Compared to a community, an ecosystem includes• the nonliving, physical environment as well as the

community.• only the physical environment of an area without the

organisms.• the entire biome but not the biosphere.• only one of the populations within the community.


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3-1

An ecological method that uses mathematical formulas based on data collected is

• observing.• experimenting.• modeling.• hypothesizing.


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3-1

An ecologist marks out an area in a specific ecosystem and proceeds to identify the number of insect species in the area. This is an example of ecological

• experimentation.• observation.• modeling.• inference.


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Producers

Where does the energy for life processes come from?

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Producers

ProducersWithout a constant input of energy, living systems cannot function.Sunlight is the main energy source for life on Earth.

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Producers

In a few ecosystems, some organisms obtain energy from a source other than sunlight.Some types of organisms rely on the energy stored in inorganic chemical compounds.

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Producers

Only plants, some algae, and certain bacteria can capture energy from sunlight or chemicals and use that energy to produce food.These organisms are called autotrophs.

Because they make their own food, autotrophs are called producers.

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Producers

Energy From the SunThe best-known autotrophs harness solar energy through

a process known as photosynthesis. During photosynthesis, these autotrophs use light energy

to convert carbon dioxide and water into oxygen and energy-rich carbohydrates.

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Producers

Photosynthesis is responsible for adding oxygen to—and removing carbon dioxide from—Earth's atmosphere.

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Producers

Life Without LightSome autotrophs can produce food in the absence of

light. When organisms use chemical energy to produce

carbohydrates, the process is called chemosynthesis.

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Producers

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Consumers

ConsumersMany organisms cannot harness energy directly from the

physical environment. Organisms that rely on other organisms for their energy

and food supply are called heterotrophs. Heterotrophs are also called consumers.

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Consumers

There are many different types of heterotrophs. • Herbivores eat plants. • Carnivores eat animals.• Omnivores eat both plants and animals.• Detritivores feed on plant and animal remains and other

dead matter. • Decomposers, like bacteria and fungi, break down organic

matter.

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Feeding Relationships

How does energy flow through living systems?

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Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers).

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Food ChainsA food chain is a series of steps in which organisms

transfer energy by eating and being eaten.

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In some marine food chains, the producers are microscopic algae and the top carnivore is four steps removed from the producer.

Algae

ZooplanktonSmall Fish

SquidShark

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Food WebsEcologists describe a feeding relationship in an ecosystem

that forms a network of complex interactions as a food web.

A food web links all the food chains in an ecosystem together.

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This food web shows some of the feeding relationships in a salt-marsh community.

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Trophic LevelsEach step in a food chain or food web is called a trophic

level.Producers make up the first trophic level. Consumers make up the second, third, or higher trophic

levels. Each consumer depends on the trophic level below it for

energy.

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Ecological Pyramids

How efficient is the transfer of energy among organisms in an ecosystem?

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Ecological Pyramids

Only about 10 percent of the energy available within one trophic level is transferred to organisms at the next trophic level.

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Ecological Pyramids

Ecological PyramidsThe amount of energy or matter in an ecosystem can be

represented by an ecological pyramid. An ecological pyramid is a diagram that shows the

relative amounts of energy or matter contained within each trophic level in a food chain or food web.

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Ecological Pyramids

Ecologists recognize three different types of ecological pyramids:

• energy pyramids• biomass pyramids• pyramids of numbers

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Ecological Pyramids

0.1% Third-level consumers

1% Second-level consumers

10% First-level consumers

100% Producers

Energy Pyramid:

Shows the relative amount of energy available at each trophic level.

Only part of the energy that is stored in one trophic level is passed on to the next level.

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Ecological Pyramids

50 grams of human tissue

500 grams of chicken

5000 grams of grass

Biomass Pyramid: Represents the amount of living organic matter at each trophic level. Typically, the greatest biomass is at the base of the pyramid.

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Ecological Pyramids

Pyramid of Numbers:Shows the relative number of individual organisms at each trophic level.

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3–2

The main source of energy for life on Earth is • organic chemical compounds.• inorganic chemical compounds.• sunlight.• producers.

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3–2

Organisms that feed on plant and animal remains and other dead matter are

• detritivores.• carnivores.• herbivores.• autotrophs.

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3–2

How does a food web differ from a food chain?• A food web contains a single series of energy transfers.

• A food web links many food chains together.• A food web has only one trophic level.• A food web shows how energy passes from producer to

consumer.

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3–2

In a biomass pyramid, the base of the pyramid represents the mass of

• heterotrophs.• primary consumers.• producers.• top level carnivores.

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3–2

The amount of energy represented in each trophic level of consumers in an energy pyramid is about

• 10% of the level below it.• 90% of the level below it.• 10% more than the level below it.• 90% more than the level below it.

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3-3 Cycles of Matter

How does matter move among the living and nonliving parts of an ecosystem?

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Recycling in the Biosphere

Recycling in the Biosphere Energy and matter move through the biosphere very differently. Unlike the one-way flow of energy, matter is recycled within and between ecosystems. Biogeochemical Cycles

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The Water CycleAll living things require water to survive.

The Water Cycle

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The Water Cycle

Water moves between the ocean, atmosphere, and land.

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Nutrient Cycles

How are nutrients important in living systems?

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Nutrient Cycles

Nutrient CyclesAll the chemical substances that an organism needs to sustain life are its nutrients.

Every living organism needs nutrients to build tissues and carry out essential life functions.

Similar to water, nutrients are passed between organisms and the environment through biogeochemical cycles.

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Nutrient Cycles

The Carbon CycleCarbon is a key ingredient of living tissue.Biological processes, such as photosynthesis, respiration, and decomposition, take up and release carbon and oxygen.Geochemical processes, such as erosion and volcanic activity, release carbon dioxide to the atmosphere and oceans.

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Nutrient Cycles

CO2 in Atmosphere

Photosynthesis

feeding

feeding

Respiration

Deposition

Carbonate Rocks

Deposition

Decomposition

Fossil fuel

Volcanic activity

Uplift

Erosion

Respiration

Human activity

CO2 in Ocean

Photosynthesis

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Nutrient Cycles

The Nitrogen CycleAll organisms require nitrogen to make proteins.Although nitrogen gas is the most abundant form of

nitrogen on Earth, only certain types of bacteria can use this form directly.

Such bacteria live in the soil and on the roots of plants called legumes. They convert nitrogen gas into ammonia in a process known as nitrogen fixation.

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Nutrient Cycles

Bacterial nitrogen fixation

N2 in Atmosphere

NH3

Synthetic fertilizer manufacturer

Uptake by producers

Reuse by consumers

Decomposition excretion

Atmospheric nitrogen fixation

Uptake by producers

Reuse by consumers

Decomposition

Decomposition excretion

NO3 and NO2

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Other soil bacteria convert nitrates into nitrogen gas in a process called denitrification. This process releases nitrogen into the atmosphere once again.

Nutrient Cycles

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Nutrient Cycles

The Phosphorus CyclePhosphorus is essential to organisms because it helps

forms important molecules like DNA and RNA.Most phosphorus exists in the form of inorganic

phosphate. Inorganic phosphate is released into the soil and water as sediments wear down.

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Organic phosphate moves through the food web and to the rest of the ecosystem.

Nutrient Cycles

Ocean

Land

Organisms

Sediments

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Nutrient Limitation

Nutrient LimitationThe primary productivity of an ecosystem is the rate at

which organic matter is created by producers. One factor that controls the primary productivity of an

ecosystem is the amount of available nutrients.

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If a nutrient is in short supply, it will limit an organism's growth. When an ecosystem is limited by a single nutrient that is scarce or cycles very slowly, this substance is called a limiting nutrient.

Nutrient Limitation

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When an aquatic ecosystem receives a large input of a limiting nutrient—such as runoff from heavily fertilized fields—the result is often an immediate increase in the amount of algae and other producers. This result is called an algal bloom. Algal blooms can disrupt the equilibrium of an ecosystem.

Nutrient Limitation

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3–3

Transpiration is part of the • water cycle.• carbon cycle.• nitrogen cycle.• phosphorus cycle.

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3–3

Carbon is found in the atmosphere in the form of • carbohydrates.• carbon dioxide.• calcium carbonate.• ammonia.

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3–3

Biologists describe nutrients as moving through cycles because the substances

• start as simple organic forms that plants need.• provide “building blocks” and energy that organisms

need.• are passed between organisms and the environment and

then back to organisms.• are needed by organisms to carry out life processes.

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3–3

The only organisms that can convert nitrogen in the atmosphere into a form useful to living things are nitrogen-fixing

• plants.• bacteria.• detritivores.• animals.

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3–3

When an aquatic ecosystem receives a large input of a limiting nutrient, the result is

• runoff.• algal death.• algal bloom.• less primary productivity.

slide 1 of 21 3-1 what is ecology? copyright pearson prentice hall

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