CHAPTER 14 LESSON 1 Interactions of Living Things

CHAPTER 14

LESSON 1

Interactions of Living Things

Ecosystems and Biomes

Key Concepts

What do you think? Read the two statements below and decide

whether you agree or disagree with them. Place an A in the Before column

if you agree with the statement or a D if you disagree. After you¡¯ve read

this lesson, reread the statements to see if you have changed your mind.

Before

Statement

? What are ecosystems?

? What are biomes?

? What happens when

environments change?

After

1. An ecosystem contains both living and

nonliving things.

2. All changes in an ecosystem occur over a long

period of time.

Copyright ? Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

What are ecosystems?

You, a wolf, and a pine tree are all living things. Living

things are also called organisms. All organisms use energy

and do certain things to survive. Organisms interact with

parts of the environment around them. Ecology is the study

of how organisms interact with each other and with their

environments.

Every organism lives in an ecosystem. An ecosystem is all

the living and nonliving things in one place. Different organisms

depend on different parts of an ecosystem to survive. For

example, a deer eats the plants and drinks the water

available in its woodland environment. The plants that the

deer eats are alive; the water it drinks is not alive. A deer

needs both the plants and the water to survive. A fish in the

stream needs water to survive. But it interacts differently

with the water than the deer does.

Abiotic Factors

Water is an example of a part of an ecosystem that was

never alive. Abiotic factors are the nonliving parts of an ecosystem.

Abiotic factors include water, light, temperature, atmosphere,

and soil. Ecosystems have different types and amounts of

abiotic factors. The types and amounts of these factors in an

ecosystem help determine which organisms can live there.

Reading Essentials

Building Vocabulary Read

all the headings in this

section and circle any word

that you cannot define. Then

underline the part of the text

that helps you define each

circled word.

Key Concept Check

1. Define What is an

ecosystem?

Interactions of Living Things

239

Water

Choose an ecosystem. Make

a two-tab book and use it to

describe the abiotic and

biotic factors that might be

found in that ecosystem.

Ecosystem:

Abiotic

Factors

Biotic

Factors

All organisms need water to live, but some need more

water than others. A cactus grows in a desert, where it does

not rain often. Ferns and vines live in rain forests, where it

rains often. The limited water in a desert means that ferns

and vines could not live successfully there.

The type of water in an ecosystem also helps determine

which organisms can live there. Some organisms need

saltwater environments, such as oceans. Humans and other

organisms must have freshwater to survive.

Light and Temperature

The amount of light an ecosystem receives and the

temperature of an ecosystem can also determine which

organisms can live there. Many organisms, such as plants,

require light energy for making food.

Temperatures in ecosystems vary. Ecosystems that receive

more sunlight generally have higher temperatures. Some

organisms need higher temperatures to survive. A fern, for

example, grows in a warm rain forest. Other organisms can

survive a wide range of temperatures. For example, a cactus

survives in the hot days and cold nights of a desert.

Atmosphere

SCIENCE USE V. COMMON USE

Science Use the mix of gases

surrounding a planet

Common Use a surrounding

influence or feeling

Soil

Different ecosystems have soil that contains different

amounts and types of nutrients, minerals, and rocks. The

texture and amount of water soil can hold also varies. Soil is

deeper in some ecosystems than in others. All of these

factors determine which organisms can live in an ecosystem.

Biotic Factors

2. Apply Suppose an

ecosystem is made up of

20 elk of the same species and

10 bears of the same species.

How many populations does

the ecosystem contain?

240

Interactions of Living Things

You read that nonliving, or abiotic, parts of an ecosystem

are important to living things. Biotic factors are all of the living

or once-living things in an ecosystem. A parrot and a fallen tree

are both biotic factors in a rain-forest ecosystem.

Populations

A population is made up of all the members of one species that

live in an area. For example, all the gray squirrels in a

neighborhood are a population. Organisms in a population

interact and compete for food, shelter, and mates.

Reading Essentials

Copyright ? Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

atmosphere

Very few organisms can live in an ecosystem without

oxygen. Earth¡¯s atmosphere contains oxygen gas as well as

other gases that organisms need. Some of these gases are

water vapor, carbon dioxide, and nitrogen.

Communities

Most ecosystems have many populations. These

populations form a community, as shown below. A

community is all the populations living in an ecosystem at the same

time. For example, populations of trees, worms, insects, and

toads are part of a forest community.

Populations interact with each other in some way. Trees

lose their leaves in the fall and the leaves become food for

worms and insects. Toads might use the leaves as they hide

from predators. Waste from these animals provides nutrients

to the trees and insects.

Biomes

The populations and communities that interact in a

desert are different from those that interact in an ocean.

Deserts and oceans are different biomes. A biome is a

geographic area on Earth that contains ecosystems with similar biotic

and abiotic features. Biomes contain ecosystems, populations,

and communities. Biomes also have specific biotic and

abiotic factors. As a result, biomes can be very different from

each other.

Key Concept Check

3. Define What is a biome?

Copyright ? Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

organism

population

Visual Check

4. Identify The figure

community

shows two different

populations in the

community. Circle the

members of one population

in one color. Circle the

members of the other

population in another color.

ecosystem

Reading Essentials

Interactions of Living Things

241

Earth¡¯s Biosphere

Visual Check

5. Name What are the

major aquatic biomes in

Earth¡¯s biosphere?

Terrestrial Biomes

Aquatic Biomes

forests

salt water

deserts

freshwater

tundra

grasslands

The part of Earth that supports life is the biosphere. As

shown above, both terrestrial and aquatic biomes are part of

the biosphere. Terrestrial means ¡°related to land,¡± and aquatic

means ¡°related to water.¡± Terrestrial biomes include forests,

deserts, tundra, and grasslands. Aquatic biomes include

saltwater areas and freshwater areas. Biomes can affect each

other. For example, a beach ecosystem is part of both a

terrestrial and an aquatic biome. Some organisms from the

terrestrial biome interact with organisms in the beach

ecosystem.

What happens when environments

change?

Response to Change

Changes can have positive effects on an ecosystem. For

example, when more rain than usual falls, more plants

might grow. Changes can also have negative effects on an

ecosystem. A very dry season could cause plants to die.

Animals might starve. Usually a change in an ecosystem has

both positive and negative effects.

Succession

Key Concept Check

6. Apply Which biotic and

abiotic factors changed after

Mount St. Helens erupted?

242

Interactions of Living Things

Over long periods of time, communities can change

through succession until they are very different. Succession

is the gradual change from one community to another community in

an area. The sudden volcanic eruption at Mount St. Helen¡¯s

created a large crater in the mountain and destroyed plant

and animal life. Its ecosystem changed suddenly. Over many

years, plant life reappeared and animals moved back into the

area. The area looks very different today than it did

immediately after the eruption in 1980.

Reading Essentials

Copyright ? Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

Natural processes and human actions cause environments

to change. Some changes can occur quickly. For example,

the erupting volcano at Mount St. Helens changed the

ecosystem suddenly. Other changes, ranging from small to

large, occur slowly. It took millions of years for the flow of a

river to carve the Grand Canyon in Arizona.

Mini Glossary

abiotic factors: the nonliving parts of an ecosystem

ecosystem: all the living and nonliving things in one place

biome: a geographic area on Earth that contains ecosystems

population: all the members of one species that live in an area

with similar biotic and abiotic features

succession: the gradual change from one community to

biotic factors: all of the living or once-living things in an ecosystem

another community in an area

community: the populations living in an ecosystem at one time

1. Review the terms and their definitions in the Mini Glossary. Write a sentence that

explains the difference between a population and a community.

2. Write each example below in the correct part of the diagram.

woodpecker

oak tree

rocks

sunlight

dead grasshopper

freshwater in a pond

Copyright ? Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.

Forest Ecosystem

Biotic factors

Abiotic factors

?

?

?

?

?

?

3. How did finding the meanings of words help you learn about the biotic factors that make

up an ecosystem?

What do you think

Reread the statements at the beginning of the

lesson. Fill in the After column with an A if you

agree with the statement or a D if you disagree.

Did you change your mind?

Reading Essentials

Connect ED

Log on to ConnectED.mcgraw-

and access your textbook to find this

lesson¡¯s resources.

END OF

LESSON

Interactions of Living Things

243

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