California science grade 5 (6)

California science vocabulary card(1 6) (4) California science grade 5 (6)

Chapter 1 Chapter 2

About 8,000 waves strike the Big Sur coastline every day.

L e s s o n 1

Introduction to Earth’s Ecosystems

6 LS 5 Organisms in ecosystems exchange energy and

nutrients among themselves and with the environment.

21

ELA R 6.3.6 Identify and analyze features of themes conveyed through characters, actions, and images • ELA W 6.2.4 Write responses to literature.

Literature

POEM

22

Redwood trees rise like skyscrapers

Fingering the clouds in search of moisturePulling down the fog and passing it

From limb to limb

Into the deep of the forest

The fog blankets the forest

Blocking out light, movement, and soundLike a curtain

Draped across a stage

Yet behind the redwood curtain

Black bear walk and stalk their prey

Deer sleep and leap away

Slugs climb and slime on leaves

Birds sing and wing in the breeze

The show must go on

As it has for thousands of years

Behind the redwood curtain

Write About It

Response to Literature In this

poem the author describes a forest What is life like in this forest? What plants and animals live there? Write an essay explaining the main idea of the poem Use details from the poem to show how the author makes her point.

- Journal Write about it online

Introduction

to Earth’s

Ecosystems

Lesson 1

California is home to one of the most diverse

collections of living things in the world Why

do you think this is so?

6 LS 5.e Students know the number and types of organisms an ecosystem can support depends on the resources available and on abiotic factors, such

as quantities of light and water, a range of temperatures, and soil composition.

24

ENGAGE

Why do certain plants and animals live in certain

places? How does the amount of sunlight affect

different organisms? Write your answer as a

hypothesis in the form “If a plant needs lots of

sunlight, then ”

Test Your Hypothesis

Experiment With your teacher select two

areas on or near your school grounds to study

Choose one area that receives plenty of sunlight

and another that receives very little Mark off

a 2-by-2-meter plot in each area with stakes

and string.

Measure Measure the air temperature at

ground level and at 1 meter above ground

level in each area.

Record Data Using graph paper record the

locations of the living things in each area What

kinds of organisms do you see? Use field guides

to help you identify the organisms.

Draw Conclusions

Compare your observations about the two areas

How do the temperatures differ? Which area

contains more living things? What statement

can you make about the effect of sunlight on

an ecosystem?

How do you think the amount of water in an

ecosystem affects living things? Make a prediction

about this, and design a procedure to test it How

have people affected the ecosystem?

Step

6 IE 7.a Develop a hypothesis • 6 IE 7.e Recognize whether

evidence is consistent with a proposed explanation.

25

EXPLORE

What Is an Ecosystem?

A system is a group of things that work

together as a unified whole There are systems all around you Our bodies contain organ systems for breathing and for digesting food Schools are organized into school systems Planets are part

of our solar system Each system is made up of parts that interact with one another closely

The living things in an area also work together in systems They all depend on the same resources and are affected by changes that occur around them For example, a major change in

a nonliving part of an ecosystem, such as an extreme drought, can affect all the organisms

in an ecosystem

Living things are part of an ecosystem

An ecosystem consists of the living and nonliving things in an area that interact with one another

An Ecosystem

▶ Main Idea 6 LS 5.e

The number and types of

26

EXPLAIN

Any living thing that is part of an

ecosystem is a biotic factor This term

includes the root bio, which means

“living.” Living things include tiny

organisms, such as bacteria, as well as

the plants and animals people can see

Any nonliving part of the ecosystem,

such as water, minerals, sunlight, air,

or soil, is an abiotic factor This term

includes the prefix a-, which means

“not” or “without.”

How can you identify the abiotic

factors in an ecosystem? Abiotic factors

are the parts of the ecosystem that

help make life possible For example,

sunlight provides warmth and energy

Rocks provide shelter and, in time,

form soil Water is so important to

living things that it is what scientists

look for first when searching for signs of life on other planets Other abiotic factors include air, climate, and altitude All these factors influence the number and types of organisms that can live in an ecosystem

Identifying the living things in an ecosystem might seem to be easy At the beach you might see birds, fish, seals, and seaweed In contrast, think about microscopic organisms inside your mouth The warm, moist environment there supports millions of bacteria

How would the abiotic factors shown here

affect the organisms that live in the pond?

Clue: What are the nonliving things in the

Why are sunlight and

temperature important?

The amount of sunlight a

location receives directly affects

the temperature in that location

Temperature, in turn, affects the

number and types of animals and

plants that can survive in a location

Sunlight

Areas of Earth that receive greater

amounts of sunlight have higher

temperatures than other areas The

equator is the part of Earth that

receives the most direct sunlight Areas

around the equator that are not at

extremely high elevations are generally

known for their lush vegetation and

great diversity of living things

The parts of Earth that receive the least direct sunlight are the North and South poles Areas near the poles have sparse or no vegetation and fewer kinds of living things For most organisms, especially plants, sunlight

is an important abiotic factor

28

EXPLAIN

▼ These penguins are adapted

to the temperatures in their

Antarctic surroundings.

In tropical rain forests, for example,

the temperature stays around 80°F

(27°C) almost all the time Many

animals and plants thrive in places

where the temperature does not change

much in a single day

In other places, the temperature

may vary from day to night and

from season to season In deserts the

temperature can vary from about 32°F

(0°C) to more than 100°F (38°C) in a

single day The plants and animals in

a desert must be able to survive these

wide variations in temperature

Changes in the seasons have similar

effects Most organisms survive better

in warm, mild summers than in

cold, icy winters In places where the

temperature changes a great deal with

the seasons, some organisms migrate,

or travel to a different place Others

become dormant, or less active, or

have other adaptations that enable them to survive

29

EXPLAIN

Central Valley irrigation

Why is water important?

Without a steady supply of water, life would not exist on Earth

Water helps living things in several ways It keeps cells strong and healthy Cells are the basic units of life Water dissolves and transports substances

It also helps regulate the temperature of an organism

Your Body’s Need for Water

Press your hands together, and they will seem

firm and solid However, about 60% to 70% of

your body is made up of water Some parts of your

body have an even greater percentage of water

It is no wonder that water is so important to

your survival

Water is the body’s main transportation

vehicle Many substances dissolve in water

This property of water is what makes it so

vital to life Water carries nutrients, oxygen,

and other substances to various parts of your body

Water also carries waste materials out of your body

Water helps regulate your body’s temperature It cools

your skin, making you feel cooler all over It also helps

carry excess heat away from your cells

30

EXPLAIN

Plants’ Need for Water

Plants, too, are made up mostly of

water Some parts of a plant, such as

the leaves and stems, may be as much as

90% water Water transports minerals

and nutrients throughout the plant

Water keeps plant cells rigid You

have probably seen what happens when

a plant does not receive enough water

The leaves and stems become weak,

and the plant wilts

Plants need water to grow For this

reason, the amount of water in an

area affects the number and types of

plants that live there Areas with little

rainfall, such as deserts, have fewer

plants The plants that do grow there

have special adaptations that allow

them to conserve water

Plants that grow in areas that receive

little rain have adapted to the dry

conditions For example, the shape of

the barrel cactus enables it to expand

when rain falls and to shrink during

dry times When it expands, this cactus

stores water in its spongy tissues

Animals have adaptations for drought

and heat, too The kit fox has large ears

with dense networks of veins These

veins help the fox’s body shed heat

One way that humans adapt to

dry conditions is to use irrigation In

places where not enough rain falls to

grow crops, farmers water their fields

Water taken from the Colorado River,

for example, irrigates almost 1 million

acres of land in Southern California

This water helps crops such as lemons,

grapes, oranges, lettuce, and tomatoes

grow on land that would otherwise be

too dry for farming

in plants and animals?

▲ barrel cactus, Anza-Borrego Desert State Park, California

31

EXPLAIN

Why is soil important?

Soil supplies the water, air, and

nutrients that plants need in order to

grow By supporting the growth of

plants, soil helps living things survive

Conservation of soil is important

We can put plants on hillsides so the

soil will not erode Farmers conserve

soil by rotating their crops and letting

fields lie fallow, or unplanted, every

few seasons

Soil Layers

Topsoil is the upper layer

of soil, which is made

mostly of humus, minerals,

water, and air The humus in

topsoil is spongy and holds

water very well This makes

topsoil an ideal material for

plants to live in.

Soil is made up of weathered rock and humus (HYEW•muhs) As rock weathers it breaks down slowly into tiny pieces Humus is the material in soil formed by the breakdown of plant and animal remains It mixes with the bits

of rock and adds nutrients to the soil.The substances in soil affect the types

of organisms that can live in it Some compounds known as acids can harm living things if they are present in high

Minerals are the

naturally occurring

solid materials of

Earth’s crust They

include clay, sand,

and silt.

The layer below the topsoil is called

the subsoil Some humus can be

found near the top of this layer As

water seeps through the topsoil into

the subsoil, it brings particles of

minerals and clay with it.

Below the subsoil is partly weathered

parent rock The parent rock is the

rock from which the soil is formed

There is no humus at this depth.

Below this layer is solid rock, or bedrock.

32

EXPLAIN

concentrations Acidity is the amount

of acid in a substance Other compounds,

known as alkalis (AL•kuh•lighz),or bases,

may also be present in soil Alkalinity

(al•kuh•LIN•uh•tee) is the amount of base

in a substance

The acidity or alkalinity of soil is

measured on a scale known as the pH

scale The lower the pH, the more acidic

the soil is The higher the pH, the more

basic or alkaline the soil is The pH of

the soil in an area helps determine which

plants will grow there If the pH of the

soil changes greatly, the plants there may

not be able to survive

Testing Soil pH

Put three different soil samples

in separate cups.

Using the soil-test kits provided

by your teacher, test the pH of each sample Record the pH

Main Idea Why is soil important?

Critical Thinking Why should people test soil before growing crops in it?

(pH 11)

drain cleaner

(pH 13)

33

EXPLAIN

California sea lions

What lives in an ecosystem?

All the abiotic factors in an area,

including temperature ranges, sunlight,

water, and soil type, influence what

living things are found there Every

organism in the ecosystem plays an

important role The study of organisms

and how they interact in an ecosystem

is ecology (ee•KAHL•uh•jee) Scientists

who study this subject include ecologists,

zoologists, biologists, foresters, geologists,

and geographers

In an ecosystem, all the organisms

of one species make up a population

The millions of bacteria living in your

mouth make up a population The

thousands of elephant seals living in

the waters off California are another

population At one time, people hunted elephant seals for their oil until only about 100 remained Today, there are many elephant seals along California’s coast California sea lions are social animals The females recognize their pups by their sounds and their smells.Ecologists study populations, looking at the role each population plays in the ecosystem They might observe behaviors such as breeding and feeding Members of a population,

or species, breed with one another and produce offspring They also compete for resources such as food, water, and shelter Almost all populations are influenced by the human population

34

EXPLAIN

34

EXPLAIN

Populations interact with other

plants and animals in their ecosystem

Different species can compete with

each other and may even try to eat

each other They can also help each

other

Populations and Communities

All the populations living in an area

make up a community To understand

this think about an orchestra All the

violins in the orchestra would make

up one population, the cellos another,

the clarinets another, and the trumpets

another Each group of instruments

represents a population, and each

group makes a unique contribution

to the community, or the orchestra

Communities are often named after

the locations in which they are found

Cactuses, sagebrush, kangaroo rats,

and jackrabbits are part of a desert

community Frogs, minnows, cattails,

and dragonflies live in a pond

community Each community includes

a group of populations that can survive

in the conditions found there

Tide-pool communities are found

where the ocean meets the land

Organisms must be able to withstand

the changing tides and the motion of

the waves

Quick Check

Main Idea What is ecology?

Critical Thinking What is the

difference between a community

and an ecosystem?

Tide-Pool Community

What items in the photo show that this is a tide-pool community?

Clue: What kinds of organisms and land features do you see?

Reading Photos

35

EXPLAIN

What roles do

organisms have?

The success of an ecosystem

depends on its ability to sustain life

For life to thrive, there must be plenty

of resources, such as food and water

In addition, the interactions among

living things must be in balance To

achieve this balance, each member

of a community has a role to play

A habitat is the place in which

a population lives Your home is a

habitat It provides you with the shelter

and food you need to survive All of

an organism’s needs must be met by

its habitat If you have ever set up an

aquarium, you know that fish require

water, the proper temperature, food,

and oxygen Some types of fish and

other aquatic organisms can share a

habitat In natural ecosystems several

populations may share the same habitat

The role of an organism in an

ecosystem is called a niche (nitch)

A niche includes everything the

organism does and everything it needs Although organisms may share habitats, they may not occupy the same niche Suppose everyone in your town had the same job and tried to eat at the same time in the same place The competition would become fierce Towns, and ecosystems, are successful because individuals and groups make different contributions

Some populations occupy niches

of such importance that many other organisms depend on them These

populations are called keystone

species For example, beavers build

dams that flood the surrounding area, creating valuable wetlands These wetlands are a rich habitat for a wide variety of living things

Wetlands help control flooding, filter pollutants from water supplies, and serve

as habitats for many organisms.

Quick Check

Main Idea What is a habitat?

Critical Thinking Why can populations share a habitat but not a niche?

36

EXPLAIN

Math Link Writing Link

Summarize the Main Idea

Ecosystems are

areas where living things interact with each other and with nonliving things

(pp 26–27)

Sunlight and temperature are

among abiotic factors that influence the living conditions in an area

(pp 28–33)

Populations include all

the organisms of one

the inside of each

fold, write two

sentences about

the main idea of

the topic.

Think, Talk, and Write

Main Idea What determines the number and types of organisms in an ecosystem?

Vocabulary In an ecosystem, all organisms of one species make up

Test Practice Which of these is considered one of the layers of soil?

Research an endangered species (plant

or animal) in or near the ecosystem in

which you live What biotic and abiotic

factors have contributed to the decline

of this species?

Monitor Population Growth

A state park contains 200 deer If the deer population doubles every year for

3 years, how many deer will live in the park? Make a line graph to show how the population changes over time.

- Review Summaries and quizzes online @ www.macmillanmh.com 37

EVALUATE

A landslide damage d these homes in Laguna B each.

These homes in La guna Beach were unaffected by a landslide.

Compare

When scientists compare they look for

similarities among objects, materials, and data As

scientists study a particular ecosystem over time,

they can make comparisons They can compare

the way the ecosystem functions in the present

with the way that it functioned in the past With

this information they can predict what the

ecosystem might be like in the future.

Learn It

When scientists study an ecosystem, they examine

every change they can Scientists study changes

because one small change in an ecosystem can affect

many biotic and abiotic factors.

Charts and Venn diagrams are tools used to compare

After you have collected and recorded data, you can see

at a glance whether the data, objects, or materials are

similar or not Line graphs and bar graphs can also be

used to analyze changing conditions over time.

Try It

▶ Scientists monitor how sudden events such as floods

and mudslides affect an ecosystem In this activity

you will compare a miniature landscape before and

after a “flood.” You will need a dishpan, soil, rocks,

small twigs, water, and a watering can.

▶ Build a hill landscape of soil, rocks, and

twig “trees” in a dishpan Draw a picture of

your landscape on a chart like the one on

this page Use the watering can to sprinkle

water gently on your hills Record your

observations.

▶ Hold the can high, and continue to let

water fall down on the hills Record

your observations Pour the rest of the

water quickly over the hills Record your

observations Draw a picture of the way

your landscape looks now.

38

EXTEND

Apply It

▶ Now use the information from your chart to create a Venn

diagram like the one on this page Draw two overlapping

ovals In one oval list the characteristics of your hill

ecosystem before the “flood.” In the other oval, list the

characteristics of your hill ecosystem after the “flood.” Write

the common characteristics in the area where the two ovals

overlap.

▶ How did your hill ecosystem change?

▶ How did it stay the same?

▶ Next, choose an ecosystem near your school or home to

observe for a month Note any changes in the ecosystem,

and make a chart or Venn diagram to compare its

characteristics at the beginning and at the end of the month.

6 IE 7.h Identify changes in natural phenomena over time without manipulating

the phenomena (e.g., a tree limb, a grove of trees, a stream, a hillslope). 39

EXTEND

Photosynthesis: The Basic

Process of Life

Lesson 2

Energy from the Sun helps a plant grow

A hummingbird gets food and energy from

a plant How does sunlight produce energy?

6 LS 5.a Students know energy entering ecosystems as sunlight is transferred by producers into chemical energy through photosynthesis and then from organism to organism through food webs.

40

ENGAGE

• growing plant (a large-leafed plant will work best)

Plants need light to grow What do you think will

happen to a plant’s leaves if you cover parts of them,

so that no light reaches those parts? Write your

answer as a hypothesis in the form “If parts of

a plant’s leaves do not receive any light, then ”

Test Your Hypothesis

Wrap small pieces of aluminum foil over parts of

several leaves Wash your hands after handling

the plant.

Use Variables Cover at least four different

leaves of the plant in the same way.

Place the plant in a window where it will get

lots of light Water the plant with a measured

amount of water.

Experiment After one day, carefully lift the

foil and check each leaf Write down your

observations Gently replace the foil in the same

position Continue your observations each day for

one week Replace the foil in the same position

each time How did the areas covered by the foil

differ from the other parts of the leaves?

Draw Conclusions

Interpret Data How did the changes you

observed progress after one day? After two

days? After a week? How do light and darkness

affect the growth of leaves?

Remove the foil from the leaves Water the plant with

the same amount of water you used in the previous

week, and observe it each day for another week

What happens when the leaves remain uncovered?

Explore More

Step

Step

6 IE 7.a Develop a hypothesis • 6 IE 7.d Communicate the steps and

results from an investigation in written reports and oral presentations.

41

EXPLORE

▶ Main Idea 6 LS 5.a

Energy enters ecosystems

as sunlight, which is used

by plants to make food.

Every living thing needs energy to live and grow Some organisms, such as animals, get their energy from eating plants Where do the plants get their energy from? Did you know that plants store energy from the Sun in their cells?

Ac[[O`g

Photosynthesis

Light

Water + Carbon dioxide → Sugar + Oxygen

Poppies use sunlight to make food.

42

EXPLAIN

Almost all organisms on Earth

depend on the Sun for energy The

Sun’s energy is stored by plants as

food during the food-making process

This activity goes on in plant cells that

have chloroplasts (KLOR•uh•plasts),

structures found in the cells of leaves

and stems of green plants Chloroplasts

contain a substance called chlorophyll

(KLOR•uh•fil), a green substance in plants

that absorbs energy from sunlight

When sunlight falls on a leaf, the

chlorophyll traps energy from the Sun

Photosynthesis (foh•toh•SIN•thuh•sis)

is the process of making food by

using sunlight Plants, and some other

organisms, take in carbon dioxide from

the air and water from the environment

The plant or other organism then

changes these two raw materials into

two products The products are sugar,

or food, and oxygen

Inside the chloroplasts the energy from the Sun is used to split the water molecules into hydrogen and oxygen The hydrogen and oxygen combine with carbon atoms to produce food

in the form of sugars Oxygen, which

is given off by the plant as a waste product, enters the atmosphere

Photosynthesis helps sustain life on Earth In addition to producing oxygen, which animals breathe, plants also take

in carbon dioxide to make food This helps our environment, because plants act as natural air scrubbers They absorb carbon dioxide that would otherwise pollute the air Then they turn it into oxygen that other living things need

What do roots and stems do?

When you think of photosynthesis, which part of the

plant do you think of first? Most people think of the leaves

However, other plant structures play important roles in

photosynthesis as well

Roots

Most roots hold plants in the soil

and take in water and minerals to feed

the plants There are two kinds of

roots: taproots and fibrous roots

Taproots are thick and straight with

a few root hairs along the sides

If you have ever tried to pull a

dandelion out of the ground, you

know that taproots grow very

deep and strong

Fibrous roots do not grow as

deep, but they branch out into

a network of thin, hairy roots

These roots can form thick mats

Plants such as marigolds and

grass have fibrous root systems

Some plants, such as orchids, have

aerial roots Aerial roots do not anchor

the plant to the ground or absorb

minerals from the soil Instead they

reach out above the ground for water

and sunlight to nourish the plant To

get the sunlight and water they need,

plants with these roots grow high in

the branches of rain-forest trees

Their green aerial roots are actually

able to carry out photosynthesis

Roots also store some of the food that

the plant produces This is why edible

roots such as carrots, sweet potatoes, and

sugar beets have such high nutritional

value When animals eat these roots,

energy from the Sun passes along to them

Parts of a Root

Root Cap A thin covering,

made up of cells, that protects the root tip as

it grows into the soil

Root Hairs Secondary

roots that are threadlike tissues on the surface of the root through which water and minerals enter

Xylem Tissue

through which water and minerals flow up through the plant

Phloem Tissue

through which food from the leaves moves down through the plant

Soft Stem Woody Stem

cambium

xylem

phloem

Stems

Stems are the parts of a plant

that support leaves and flowers The

stem also transports water and other

substances between the roots and

leaves Why do you think plants need

to hold their leaves up to the Sun? They

need to do this so they can receive as

much sunlight as possible to carry out

photosynthesis

Look at the diagram on this page

Inside the stem are tubes called xylem

(ZIGH•luhm) and phloem (FLOH•uhm)

Xylem carries water and minerals up

from the roots through the plant to

the leaves Phloem carries food from

the leaves to other parts of the plant

Xylem and phloem may be separated

by another layer of cells called the

cambium.

Stems also help store energy Like

roots some stems store energy in the

form of food Sugarcane is an example

of an edible stem Some plants, such as asparagus, have photosynthetic cells in their stems that can help make food Other plants use stems as a reservoir for water In what environment do you think it is very important for plants to store large amounts of water? You are correct if you said, “The desert.” Some kinds of cactuses can store enough water to get through several days or even several years without rainfall!

Parts of a Stem

How are the xylem, the phloem, and the cambium arranged differently in a woody stem and in a soft stem?

Clue: Compare the drawings of the two types of stems How are they alike? How are they different?

What are leaves?

Look at a leaf from a tree or

a shrub You might have difficulty

accepting the fact that the leaf is such

a powerful food-making machine

Inside the thin blade of the leaf are

the structures that provide Earth with

food, oxygen, and clean air Leaves

with only one blade are simple leaves

Leaves with two or more blades are

compound leaves.

The parts of a leaf work together

to help keep the plant alive The

outermost part of a leaf is its epidermis

(ep•i•DUR•mis) Cells of the epidermis

secrete a waxy coating called a cuticle

(KYEW•ti•kuhl) This waxy covering helps prevent water from leaving the plant The leaf makes food in cells between the layers of the epidermis These cells contain chloroplasts The epidermis on the lower surface of a leaf contains many tiny pores called

stomata (STOH•muh•tuh) (singular,

stoma) Stomata open and close to

let gases, such as carbon dioxide and oxygen, in and out These openings also control the amount of water

that leaves the plant Guard cells

surrounding the stomata regulate when the stomata open and close

Parts of a Leaf

46

EXPLAIN

How Leaves Work

The veins that run through the

leaf blade bring water and minerals

to the last stop on their journey from

the roots When carbon dioxide enters

through the stomata and sunlight is

captured by the chlorophyll in the

chloroplast, all the ingredients are

in place to produce food

Some leaves, such as those of

spinach or lettuce, store food Others

are designed to protect the plant The

spines on a cactus are actually the

leaves They do a good job of protecting

the plant from being eaten, and their

small size and pointed shape minimize

water loss in the dry environment of

a desert

In some areas of the world

where there are seasonal changes in

temperature, plants shut down their

food-making factories at certain times

of year During the winter months, they

live off the food they have stored Green

chlorophyll disappears from the leaves

When this happens people can see the

other colors, such as yellow and orange,

that are usually masked by the green

pigment Maple trees, as well as some

other plants, store sugar in their leaves

The stored sugars trigger the formation

of a red pigment, giving these plants

their vibrant autumn colors

Leaves

Collect a variety of leaves.

Observe Examine each leaf with

a hand lens, and write down each structure that you can identify.

Place a piece of white paper over the leaf, and rub back and forth with a crayon, making a print of the leaf.

Identify On the rubbing, identify the leaf as simple or compound, and label each structure.

Using two different-color crayons, trace the flow of water and food through the veins.

Quick Check

Summarize What do leaves do

for a plant?

Critical Thinking What is the

difference between a simple leaf

and a compound leaf?

47

EXPLAIN

sequoia tree, Sequoia National Park, California

How does water move through plants?

Roots absorb water and minerals from the soil The stems and leaves transport the water and minerals throughout the plant This might not seem like a huge task in a small plant, but how can water reach the top of a 90-meter (295-foot) giant sequoia?

Several forces work together to move water through a plant Pressure builds up in the roots and forces water to

move upward into the stems In small plants root pressure

alone can move water all the way through the plant However,

in most plants root pressure is not enough to push water through tall stems and into leaves Forces that pull the water upward are needed as well

Capillary action is one force that pulls water up into plants

Water molecules stick to one another and to other substances, such as glass, cloth, cells, and soil You can observe capillary action by dipping the corner of a paper towel into a glass of water The water will appear to climb up the paper towel.The other force that pulls water upward through a plant

is caused by evaporation Transpiration (trans•puh•RAY•shuhn)

is the loss of water from plant leaves The water in the plant travels up through the veins of the leaves, and then it evaporates into the atmosphere through the stomata As the plant loses water, more water moves into the plant cells to take the place of the water that has been lost

These three forces—root pressure, capillary action, and transpiration—work together to keep water moving through the parts of the plant These forces help the plant carry out photosynthesis and keep it from wilting

Quick Check

Summarize What three forces move water upward through a plant?

Critical Thinking What would happen to the plant if

it did not have stomata on the bottoms of its leaves?

◀ A huge tree can move more than 1,800 liters (476 gallons)

of water from the ground to its leaves each day Most people drink about 2 liters (4 pints) of water each day.

48

EXPLAIN

petiole

xylem

How Water Moves Through a Plant

Water and dissolved minerals enter the plant’s root hairs from the soil

Pressure builds up in the roots as water moves in.

What causes water to travel from a plant’s

roots to its stem?

Clue: Follow the path of the blue arrows in

the diagram, and read the text on page 48.

Reading Diagrams

Watch how plants transport water @ www.macmillanmh.com

The water is pushed upward

into the xylem and travels

up the stem Capillary

action pulls water up

through the xylem.

Loss of water through transpiration in the leaves helps pull the water upward through the xylem toward the top of the plant.

Almost 99% of the water that enters the roots is given off into the air by transpiration through the leaves’ stomata.

Water moves up the stem,

through a leaf’s petiole,

and into the leaf’s veins

The veins carry the water

to the leaf’s cells.

49

EXPLAIN

What happens during

respiration?

When food is eaten, energy passes from

organism to organism Every time energy

is passed along, some energy is lost Each

organism uses some of the energy for its own

daily activities How does a plant or animal

use the energy that is stored in the food it eats?

When an organism needs fuel, its cells can

use oxygen to break apart food molecules The

release of energy in plants and animals from

food is called respiration (res•puh•RAY•shuhn)

In respiration, which occurs in plants and

animals, sugars and oxygen join to produce

water, carbon dioxide, and energy

Photosynthesis

Light Water + Carbon dioxide → Sugar + Oxygen

happens only in cells with chloroplasts

needs sunlight stores energy turns energy to a sugar produces oxygen uses water to make food uses carbon dioxide

Respiration

Sugar + Oxygen → Carbon dioxide + Water + Energy

happens in most cells happens in light or dark releases energy turns a sugar to energy uses oxygen produces water produces carbon dioxide

Quick Check

Summarize What role does

respiration play in cells?

Critical Thinking Why can

photosynthesis and respiration

be considered reverse processes?

Apples contain energy stored

during photosynthesis.

50

EXPLAIN

Write a Narrative

Describe the journey of a water

molecule through a plant How does

it enter the plant? How does it move

through the plant? How does it exit

the plant?

Calculate Oxygen Released

A forest produces 56 liters of oxygen

in 1 week A single plant can produce

1 liter per week How long will it take the forest to produce enough oxygen

to fill a 10,000-liter tank?

Summarize the Main Idea

Photosynthesis is the

process in which plants convert energy from the Sun into usable chemical energy stored as food.

(pp 42–43)

Roots and stems

transport water and other substances between the roots and the leaves

(pp 44–49)

During respiration,

plants and animals release energy from food

Use the titles shown

On the inside of each

tab, summarize how

that topic can help you

understand how plants

make food.

Think, Talk, and Write

Main Idea How does energy enter ecosystems?

Vocabulary The process by which plant leaves lose water is

Summarize How does root pressure differ from transpiration?

Critical Thinking Explain the relationship between plants and an atmosphere suitable for sustaining life.

Test Practice In addition to carbon dioxide, is one of the products of respiration.

A sugar

B oxygen

C chlorophyll

D energy

Test Practice What is the process

of making food by using sunlight?

Until recently scientists thought that all life on Earth depended on sunlight

In the 1970s they made a startling discovery They found creatures on the ocean floor that did not need sunlight

to live The question, then, was how these creatures could survive on the cold, dark ocean floor

Earth’s mantle contains hot, melted rock called magma When breaks in Earth’s crust occur on the ocean floor, magma wells up, fills in the spaces, and gushes forth as a hot liquid called lava

Good expository writing

▶ introduces the main idea

and develops it with facts

and supporting details.

▶ gives important information

about a topic.

▶ summarizes information

from a variety of sources.

▶ uses transition words, such

as therefore and then, to

connect ideas

▶ draws a conclusion based

on the facts and information

presented.

Life in the

These worms live near hot-water vents on the ocean floor They eat bacteria that live on chemicals in the water.

galatheid crab

ELA W 6.1.2 Create multiple-paragraph expository compositions: a Engage the interest

of the reader and state a clear purpose b Develop the topic with supporting details and precise verbs, nouns, and adjectives to paint a visual image in the mind of the reader

c Conclude with a detailed summary linked to the purpose of the composition.

52

EXTEND

The lava contains large amounts

of various chemicals that bacteria

feed on These hot spots are called

hydrothermal vents Scientists found

worms, clams, crabs, mussels,

and fish living near these vents

The animals survive in this dark

environment by eating these bacteria

Most life on Earth depends on

sunlight and on photosynthesis—but

not all life does! Nature is full of

surprises

Write About ItExpository Writing Write a report telling how sunlight helps support your life Engage your reader right away, and clearly state your purpose for writing Introduce the main idea, and develop it with facts Use supporting details and precise verbs, nouns, and adjectives to describe and explain your subject Do print and online research Summarize your findings at the end of the report.

- Journal Write about it online

@ www.macmillanmh.com

53

EXTEND

Lesson 3

Microscopic

Organisms

on Earth

Did you ever think about where some of the most

amazing and beautiful organisms can be found? Look at

several drops of pond water through a microscope The

paramecium shown here is one part of the fascinating

world of microscopic organisms

6 LS 5.b Students know matter is transferred over time from one organism to others in the food web and between organisms and the physical environment.

54

ENGAGE

What can you see through

a microscope?

Make a Prediction

What do you think you will see if you look at an

onion skin, sand, or yeast under a microscope? Write

your prediction in the form “If I look at an onion skin,

sand, or yeast under a microscope, then ”

Test Your Prediction

Observe Place a piece of newspaper on a

microscope slide Place the slide on the stage

of the microscope, and observe it under

low power Draw what you see Look at the

newspaper again under high power Record

your observations.

Observe Select your own samples Repeat

step 1 for each sample Record what you see.

Record Data Make a data table to record

the details of what you observed How many

organisms did you observe? How big were

they? What colors were they?

Draw Conclusions

Observe What did you learn about the

way objects appear when viewed through a

microscope? What happened to your observations

as you changed from low power to high power?

Observe Describe the appearance of each

of the samples you observed.

Step

Materials

Did you see any differences among the samples

under the microscope? Research the types of cells

you looked at Analyze and present your results.

Explore More

Step

• microscope

• 4 microscope slides

6 IE 7.b Select and use appropriate tools and technology

(including calculators, computers, balances, spring scales,

microscopes, and binoculars) to perform tests, collect data,

and display data.

55

EXPLORE

]PXSQbWdSZS\a

abOUS RWO^V`OU[

POaS

TW\S ORXcab[S\b Y\]P

Q]O`aSORXcab[S\b Y\]P

abOUSQZW^a

O`[

ZWUVb a]c`QS

Compound Microscope

▶ Main Idea 6 LS 5.b

Energy and matter are

transferred from one

Classify and Categorize

What are microscopic organisms?

Microscopic organisms are found everywhere They live and grow on every surface in the

world Some are producers, which can make their own food by photosynthesis Others are consumers, which eat other organisms for food Some are decomposers, which break down and consume dead organisms Microorganisms are

an important part of Earth’s ecosystems They provide larger organisms with some of the food and oxygen they need to survive They help enrich the environment by breaking down dead organisms

What parts of the microscope would

you use to change the focus?

Clue: Look at the diagram, and read

the labels.

Reading Diagrams

56

EXPLAIN