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Copyright © by Harcourt, Inc.
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Printed in México
ISBN 978-0-15-362037-9
ISBN 0-15-362037-4
2 3 4 5 6 7 8 9 10
805
16 15 14 13 12 11 10 09 08
VOCABULARY
organism
microscopic
bacteria
protist
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8aVhh^[^ZY4
An organism is a living
thing. The frog and the
duckweed are both
organisms.
2
Microscopic organisms are
so small they cannot be
seen with the eyes alone.
They must be viewed with a
microscope.
Bacteria are a type of one-celled organism.
A bacteria cell does not have a nucleus.
A protist is another type of organism.
Most protists have one cell.
3
READING FOCUS SKILL
B6>C>9:66C99:I6>AH
A main idea is what the text is mostly about. Details
tell more about the main idea.
Look for details that tell how living things are classified.
8aVhh^[n^c\A^k^c\I]^c\h
There are millions of kinds of organisms on Earth. An
organism is a living thing. You can group organisms
into five kingdoms: plants, animals, fungi, bacteria, and
protists.
You know what plants and animals are. Fungi look a
little like plants but cannot make their own food.
Microscopic organisms cannot be seen with the eyes
alone. Most have just one cell. One-celled organisms
are in the bacteria and protist kingdoms.
Tell how scientists classify organisms.
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Cells are the building blocks of life. Every organism is
made up of one or more cells. Most cells are microscopic.
They all need food and water. They need a way to get rid
of wastes.
Every cell has a membrane. A cell takes in materials and
gets rid of wastes through the membrane. Each plant
and animal cell has a nucleus, too. The nucleus controls
everything the cell does.
Tell what parts plant and animal cells both have.
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5
=dl8Zaah6gZ9^[[ZgZci
Plant cells are different from animal cells in some
ways. Plant cells have stiff cell walls and chloroplasts.
Chloroplasts are where food is made.
Cells make new cells by dividing. Organisms with more
than one cell grow as their cells divide.
How are plant cells different from animal cells?
:kZgneaVciXZaa
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One-celled organisms are microscopic. They also grow
and reproduce. They make two identical organisms when
they divide.
Some one-celled organisms make their own food.
Algae do this. They have chloroplasts like plants. Other
one-celled organisms do not have chloroplasts. Amoebas
belong in this group.
Tell how one-celled organisms reproduce.
7
7VXiZg^V
Bacteria live in every part of the world. They live in
and on you, too.
Bacteria are often grouped by shape. Some are
rod-shaped. Others look like balls. Some have spiral
shapes. A bacteria cell does not have a nucleus.
Bacteria can be helpful and harmful. Some cause
infection. Others help you digest food.
Tell how bacteria are often grouped.
7VXiZg^VXdbZ^c
bVcnh]VeZh#
8
Egdi^hih
Most protists are one-celled organisms called algae and
protozoans. Algae are found in fresh and salt water. They
also grow on rocks and trees. They make their own food.
Protozoans do not make their own food. They eat
other protists and bacteria. The amoeba is one type of
protozoan.
Tell which two groups
make up protists.
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bVnWZ[djcY^cV
Ygded[edcYlViZg#
Review
8dbeaZiZi]^hbV^c^YZVhiViZbZci#
1. Many Scientists classify _______ into five
kingdoms to study them.
8dbeaZiZi]ZhZYZiV^ahZciZcXZh#
2. All organisms are made up of one or
more _______.
3. _______can be both helpful and harmful.
4. Only _______ have cells with stiff cell walls and
chloroplasts.
9
VOCABULARY
vascular
nonvascular
fungi
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Vascular means “having
tubes.” A vascular plant
has tubes that carry water
and food to all parts of the
plant.
10
Nonvascular means
“without tubes.” A
nonvascular plant, such as
moss, does not have tubes
that carry water or food.
Fungi are organisms that cannot move about. But
unlike plants, fungi cannot make their own food.
11
READING FOCUS SKILL
B6>C>9:66C99:I6>AH
A main idea is what the text is mostly about.
Details tell more about the main idea.
Look for details that tell how plants and fungi are
classified.
KVhXjaVgEaVcih
Scientists classify plants
into two groups. One group
is made up of vascular
plants. Vascular means
“having tubes.” Vascular
plants have tubes that carry
water and food to all parts of
the plant.
Vascular plants have three
systems—roots, stems, and
leaves. Roots hold the plant
in the ground. Roots take
in water and other things
needed for growth. They
also store food.
Stems connect the roots
and leaves. They carry water
and food. The stem helps the
plant stand up.
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12
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Leaves make food and give
off oxygen. A plant cell’s
chloroplasts use the sun’s light
energy, carbon dioxide, and
water to make sugar. The plant
uses this for food. This process
is called photosynthesis.
Vascular plants are divided
into three smaller groups. One
group makes seeds in fruits.
Another group makes seeds in
cones. The third group makes
spores to make new plants.
Name the three systems
that all vascular plants
have.
13
CdckVhXjaVgEaVcih
Nonvascular plants are the other group of plants.
Nonvascular means “without tubes.” Nonvascular plants
do not have tubes to carry water or food. Instead, they
soak up water that surrounds them.
Nonvascular plants grow close to the ground. Water
moves from cell to cell in these plants. They do have
leaflike parts that make food.
Mosses are the most common nonvascular plants.
They grow on buildings, brick walls, and damp
pavements. They also grow along rivers and in damp
forests.
Tell how nonvascular plants get water.
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14
;jc\^
Fungi are organisms that take in food, but cannot
move about. Fungi have stiff cell walls and look a little like
plants. But fungi cannot make their own food.
Instead, fungi take in what they need to grow from
living and dead organisms. These materials, called
nutrients, are taken into their cells.
Fungi include mushrooms and bread molds.
How do fungi get their food?
NZVhi^hV[jc\jhjhZY
idbV`ZWgZVYg^hZ#
Review
8dbeaZiZi]^hbV^c^YZVhiViZbZci#
1. All plants can be divided into
different groups.
8dbeaZiZi]ZhZYZiV^ahZciZcXZh#
2. All vascular plants have
water.
3.
that take in
soak up the water around them
because they do not have tubes.
must take food in
4. Unlike plants,
because they cannot make it themselves.
15
VOCABULARY
vertebrates
invertebrates
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8aVhh^[ZY4
Vertebrates are a group of animals that have a
backbone.
16
Invertebrates are a group of animals that do not
have a backbone.
17
READING FOCUS SKILL
B6>C>9:66C99:I6>AH
A main idea is what the text is mostly about. Details
tell more about the main idea.
Look for details about the characteristics of
vertebrates and invertebrates.
KZgiZWgViZh
There are many kinds of animals. Scientists classify
animals into two groups—vertebrates and invertebrates.
Vertebrates are animals with a backbone. You are a
vertebrate.
Vertebrates are the most complex of all animals. They
have many body systems. Vertebrates have a system of
nerves. They have systems that bring nutrients, water, and
oxygen to each cell.
What makes vertebrates complex animals?
H `jc`hVgZ
kZgiZWgViZhWZXVjhZ
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18
BVbbVah!hjX]Vh
i]^h`Vc\Vgdd!VgZ
kZgiZWgViZh#
BVbbVahVcY7^gYh
There are five groups of vertebrates. These groups
are mammals, birds, reptiles, amphibians, and fish. The
animals in each group have a backbone.
The bodies of all mammals stay at the same
temperature no matter what the air temperature is. Most
mammals have hair or fur. Their young are born live. You
are a mammal.
Most birds can fly. They have wings with feathers. All
birds lay eggs.
Name the five vertebrate groups.
7^gYhVgZkZgiZWgViZh#
19
CXENL07ARD401_LLR.indd 19
First Pass
12/28/09 7:25:04 PM
GZei^aZh!6be]^WVch!VcY;^h]
Reptiles live on land. They are covered with scales. The
bodies of reptiles are the same temperature as the air
around them. Reptiles lay eggs on land. Lizards, turtles,
and snakes are reptiles. Some reptiles have live young.
Most amphibians lay eggs and begin life in water.
They take in oxygen with gills instead of lungs. As they
develop, they grow legs and lungs. They have smooth
skin. Frogs, toads, and salamanders are amphibians.
Fish live in water. Their fins and tails help them swim.
Their gills take in oxygen from the water.
Tell three things
about all reptiles.
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hjeedgih^i^clViZg#
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20
CXENL07ARD401_LLR.indd 20
First Pass
12/28/09 7:36:34 PM
>ckZgiZWgViZh
Animals without a backbone are Invertebrates. There
are more than a million kinds of invertebrates.
Scientists classify invertebrates by their body parts
and how these parts are put together. Sponges are one
group. They are very simple but have many cells. Jellyfish
and sea anemones are another group. Their bodies are
like sacks.
How do scientists decide in which group an
invertebrate belongs?
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21
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First Pass
12/28/09 7:18:14 PM
Bdaajh`h!Ldgbh!VcY6gi]gdedYh
Snails and clams are mollusks. They have soft bodies.
Many have shells. Invertebrates also include several
groups of worms.
The arthropods are the largest group of invertebrates.
All arthropods have jointed legs. They have a rigid body
covering. Crabs and shrimp are arthropods. So are spiders
and scorpions.
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22
CXENL07ARD401_LLR.indd 22
First Pass
12/28/09 7:06:00 PM
Insects are the largest group
of arthropods. An insect has three
body parts. Insects have six jointed
legs. Most insects have antennae.
Name three arthropods.
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VgZ^chZXih#
Review
8dbeaZiZi]^hmain ideahiViZbZci#
1. Scientists classify all animals into
groups.
main
8dbeaZiZi]ZhZYZiV^ahiViZbZcih#
2. Vertebrates are animals that have a
.
3. Animals that do not have a backbone are
.
called
4. People are vertebrates that belong to the
group.
23
GLOSSARY
bacteria (baksTIRseesuh) one of the kingdoms of onecelled living things
fungi (FUHNsjy) organisms that can’t make food and can’t
move about
invertebrates (insVERstuhsbrits) the group of animals
without a backbone
microscopic (myskruhsSKAHPsik) too small to be seen with
the eyes alone
nonvascular (nahnsVASskyuhsler) without tubes
organism (AWRsguhsnizsuhm) a living thing
protist (PROHTsist) one of the kingdoms of living things that
are mostly one-celled
vascular (VASskyuhsler) having tubes
vertebrates (VERstuhsbrits) the group of animals with a
backbone
24
I]^c`6Wdjii]ZGZVY^c\
Think About the Reading
1. Name the five kingdoms.
2. Explain how scientists use cells to classify organisms
into the kingdoms.
=VcYh"Dc6Xi^k^in
Hands-On Activity
Cut out or draw pictures of animals.
1. Label each animal with its name and identify
whether it is a vertebrate or invertebrate and the
group it belongs to.
2. Choose one animal. Do research on it and write
about it in the form of a children’s book.
HX]dda"=dbZ8dccZXi^dc
School-Home Connection
Take a walk with a family member. Look for organisms in
the plant, fungi, and animal kingdoms and make a tally
chart of your findings. Explain how you knew in which
kingdom each organism belonged.
GRADE 4
Book 1
WORD COUNT
1457
GENRE
Expository NonÞction
LEVEL
See TG or go Online
Harcourt Leveled
Readers Online Database
www.eharcourtschool.com
ISBN-13: 978-0-15-362037-9
ISBN-10: 0-15-362037-4
>
j]Y+6.%3'Z[W
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