chapter: ecology

Chapter: Ecology

Table of ContentsTable of Contents

Section 3: Energy Through the Ecosystem

Section 1: What is an ecosystem?

Section 2: Relationships Among Living Things

• An ecosystem is made up of organisms interacting with one another and with nonliving factors to form a working unit.

Ecosystems

What is an ecosystem?What is an ecosystem?

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• Organisms, along with the nonliving things in the woods or yard, such as soil, air, and light, make an ecosystem (EE koh sihs tum).

• Ecology is the study of the interactions that take place among the living organisms and nonliving parts of an ecosystem.

• Ecologists spend a lot of time outdoors, observing their subject matter up close.

The Study of Ecosystems


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• Like other scientist, ecologists also conduct experiments in laboratories.

• But, most of the ecologist's work is done in the field.

The Study of Ecosystems


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• The biosphere (BI uh sfihr) is the largest ecosystem on Earth.

• The biosphere is the part of Earth where organism can live.

The Largest Ecosystem


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• It includes the topmost layer of Earth's crust; all the oceans, rivers, and lakes; and the surrounding atmosphere.

• The biosphere is made up of all the ecosystems on Earth combined.

The Largest Ecosystem


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• Each of the many ecosystems in the biosphere contains many different living organisms.

• The organisms that make up the living part of an ecosystem are called biotic factors.

Living Parts of Ecosystems


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• An organisms depends on other biotic (bi AH tihk) factors for food, shelter, protection, and reproduction.

• The nonliving things found in an ecosystem are called abiotic (ay bi AH tihk) factors.

• Abiotic factors affect the type and number of organisms living in ecosystems.

Nonliving Parts of Ecosystems


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• One abiotic factor that can affect which plants and other organisms are found in an ecosystem is soil.

• Soil is made up of a combination of minerals, water, air, and organic matter—the decaying parts of plants and animals.

Soil


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Soil


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• Different amounts of minerals, organic matter, water, and air make different types of soil.

Click image to view movie.

• Temperature also determines which organisms live in a particular place.

Temperature


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• Another important abiotic factor is water.

Water


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• Some organisms, such as fish, whales, and algae (AL jee), are adapted for life in water, not on land.

• But these organisms depend upon water for more than just a home.

• Water helps all living things carry out important life processes such as digestion and waste removal.

Water


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• In fact, the bodies of most organisms are made up mostly of water.

• Scientists estimate that two-thirds of the weight of the human body is water.

• The amount of water available in an ecosystem can determine how many organisms can live in a particular area.

Water


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• It can also serve as shelter and as a way to move from place to place.

• The Sun is the main source of energy for most organisms on Earth.

Sunlight


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• Energy from the Sun is used by green plants to produce food.

• When you eat food produced by a plant, you are consuming energy that started out as sunlight.

• Every ecosystem is made up of many different biotic and abiotic factors working together.

A Balanced System


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• When these factors are in balance, the system is in balance, too.

• Many events can affect the balance of a system.

• One example would be a long period of time without rain (called a drought).

11Section CheckSection Check

Question 1

A. turtles eat insects you place in the aquarium B. turtles fight each other for foodC. turtles move onto rocks heated by sunlightD. turtles pull into their shells when you startle them

An aquarium of turtles can be considered a small ecosystem. Which of the following is an example of how the turtles could interact with an abiotic part of the aquarium ecosystem?

11Answer

Section CheckSection Check

The correct answer is C. Sunlight is an abiotic factor. When turtles warm themselves in the sunlight, they are interacting with this nonliving part of the ecosystem.


Question 2

The biosphere is the largest ecosystem on Earth.It is the part of Earth where organisms can liveand includes parts of Earth’s crust, waters, andatmosphere.

What is the largest ecosystem on Earth?

Answer


Question 3

Which represents the weight of the human body that is made up of water?

A. 1/4B. 1/3C. 1/2D. 2/3

11Answer


The correct answer is D. Scientists estimate that two-thirds of the weight of the human body is water.

Organizing Ecosystems

• When ecologists study living things, they usually don't start by studying the entire biosphere.

• To separate the biosphere into smaller systems that are easier to study, ecologists find it helpful to organize living things into groups.

Relationships Among Living ThingsRelationships Among Living Things

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Groups of Organisms• A population is a group of the same type of

organisms living in the same place at the same time.

• Some populations that you might find in a coral reef ecosystem are sponges, algae, sharks, and coral.


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Groups of Populations• All of the

populations that live in an area make up a community (kuh MYEW nuh tee).

• The members of a community depend on each other for food, shelter, and other needs.


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Characteristics of Populations

• Ecologists ask questions to describe populations.

• They want to know the size of the population, where it members live, and how it is able to stay alive.


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Population Density

• Ecologists determine population density (DEN suh tee) by comparing the size of a population with its area.

• For instance, if 100 dandelions are growing in a field that is one square kilometer in size, then the population density is 100 dandelions per square kilometer.


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Studying Populations

• To study migrating monarchs, a "monarch watcher"—often a school student like yourself—carefully catches a monarch and attaches a tag to one of its wings.

• Later, someone else who catches the same butterfly can use the tag to figure out how far the butterfly has flown.


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Studying Populations• Information from many butterflies can be

combined to build a picture of the monarch's migration.

• Similar techniques are used to study populations of birds, wolves, and other animals that travel long distances.


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Limits to Populations

• Populations cannot grow larger and larger forever.

• The things that limit the size of a population, such as the amount of rainfall or food, are called limiting factors.


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Limits to Populations

• One biotic limiting factor in stream ecosystem is the mosquito population.

• Frogs eat mosquitoes.


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• If lack of rain caused the mosquito population to go down, then the frog population might not have enough food and its population size might also decline.

Interactions in Communities• Feeding interactions are the most common

interactions among organisms in a community.

• The greater the population size of an area, the greater the competition for resources such as food.


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Interactions in Communities

• One of the most common ways organisms interact in a community is by being food for another organism.


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Interactions in Communities

• Organisms will compete for any resource that is in limited supply.


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• Space, water, sunlight, and shelter are all resources that may be limited in a particular ecosystem.

Eat or Be Eaten• A falcon is a bird of prey, which means it

captures and eats other animals.


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• The falcon is a predator (PRE duh tur).

• Predation (pre DAY shun) is the act of one organism feeding on another.

Organisms That Live Together

• There are other types of relationships among organisms.


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• In one type of interaction, both organisms in the relationship benefit.

Organisms That Live Together• In another type of relationship, only one

organism benefits.


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• The other organism doesn't benefit, but it is not harmed.

• A bird building a nest in a tree is an example of this.

• The bird gets protection from the tree, but the tree isn't harmed.

Organisms That Live Together

• In still another relationship, one organism is helped while the other is harmed.


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• Have you ever been bitten by a mosquito?

• That's a firsthand experience of this type of relationship.

Where and How Organisms Live

• The role of an organism in an ecosystem is called the organism's niche (NICH).


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• What do you think the role of the fish might be in an aquarium ecosystem?

• The niche of the fish includes adding nutrients to the ecosystem through its waste products that encourage the growth of algae.



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• Different species of organisms often live in the same habitat.

• The place where an organisms lives is called its habitat(HA buh tat).



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• Each species has a different niche within the same habitat.

• Resources, such as food, living space, and shelter, areshared among all the species living in a habitat.


A. flock of birds that includes pigeons, sparrows, and doves B. forest of trees and all the birds that live in themC. group of elephants in Africa and another group in IndiaD. group of gray squirrels that live in a park together

Which represents a population?

Question 1


The correct answer is D. A population is a group of the same type of organisms living in the same place at the same time.

Answer


Question 2What type of information would you need to collect concerning the monarch butterflypopulation in order to prepare a map like this one showing the migration of monarchs?


A. How long butterflies liveB. what foods butterflies eatC. when butterflies fly through certain areas D. when butterflies lay their eggs


The correct answer is C. A Butterfly can be captured and tagged to indicate where it was caught. When the same butterfly is captured later, the tag can be used to figure out how far the butterfly has flown.

Answer


Question 3

A niche is the role of an organism in anecosystem; like how it obtains food. Anorganism’s habitat is where it lives.

What is the difference between an organism’s niche and its habitat?

Answer

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It’s All About Food

• Energy moves through an ecosystem in the form of food.

• In any community, energy flows from producers to consumers.

Energy Through the EcosystemEnergy Through the Ecosystem

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Producers and Consumers• An organism that makes its own food, like a

plant, is called a producer.

• The grasshopper that nibbles on the plants is a consumer.


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• A consumer eats other organisms.

Decomposers• Some of the consumers in an ecosystem are

so small that you might not notice them, but they have an important role to play.

• Decomposers use dead organisms and the waste material of other organisms for food.


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Modeling the Flow of Energy• The food chain is a simple model that shows

how energy from food passes from one organism to another.

• Each organism is linked by an arrow.


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• The arrows show that energy moves from one organism to another in the form of food.

Modeling the Flow of Energy

• A food chain does not show every species in the community.


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• Scientists use a more complicated model, called a food web, to show the transfer of energy in a ecosystem.


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• A food web is a series of overlapping food chains that shows all the possible feeding relationships in an ocean ecosystem.

Cycling of Materials

• Cycles are important to ecosystems.

• Materials that make up organisms get recycled in an ecosystem.


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• The bodies of living things are made up of matter, including water and chemicals like nitrogen and carbon.

Cycling of Materials

• In an ecosystem, matter cycles through food chains.

• The amount of matter on Earth never changes.


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• So matter in ecosystem is recycled, or used again and again.


A. consumer B. decomposerC. predatorD. producer

On a walk through the woods, you notice fungi growing on a dead tree. What is the role of fungi in the forest ecosystem?

Question 1


The correct answer is B. Decomposers, like fungi, use dead organisms and the waste materials of other organisms for food.

Answer


Question 2

What do scientists use to show how energy is transferred in an ecosystem?

Answer

They use food webs to show the transfer of energy. A food web is a series of overlapping food chains that shows all the possible feeding relationships in an ecosystem.

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A. cyclesB. habitats C. populationsD. water

Without _______ ecosystems would eventually run out of matter that organisms need to grow.

Question 3


The correct answer is A. Matter is recycled in ecosystems through food chains. In an ecosystem, matter is used over and over again.

Answer

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End of Chapter Summary File

chapter: ecology

Documents

living thingsan ecosystem

different living organisms

number of organisms

abiotic factors

nonliving factors

water available

study of ecosystemswhat

parts of plants