4 1 plant animal classification (life science)

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Classifying Plants
and Animals

Scott Foresman Science 4.1

ISBN 0-328-13860-6

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Vocabulary
cell
chloroplast
cytoplasm
genus
invertebrates
nucleus
species
vertebrates

Picture Credits
Every effort has been made to secure permission and provide appropriate credit for photographic material.
The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions.
Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd).
Opener: (B) Bryan F. Peterson/Corbis, (C) Frans Lanting /Minden Pictures; 4 (BR) Science Photo Library/
Photo Researchers, Inc.; 8 (CR) Mary Ann McDonald/Corbis (CB, CRB) ”Jerry Young/DK Images;
9 (CL, CR, C, C1) Mary Ann McDonald/Corbis, (CLB, CBL, CBR, CRB) ”Jerry Young/DK Images, (CA, CAR, CRA) ”Barry Watts/
DK Images; 13 (CR) Bryan F. Peterson/Corbis, (BR) Frans Lanting /Minden Pictures; 18 (BR) Fred Bavendam /Minden Pictures;
19 (T) Ken Lucas/Ardea, (BC) Fred Bavendam/Minden Pictures; 22 Kennan Ward/Corbis.
Unless otherwise acknowledged, all photographs are the copyright © of Dorling Kindersley, a division of Pearson.

ISBN: 0-328-13860-6
Copyright © Pearson Education, Inc. All Rights Reserved. Printed in the United States of America.
This publication is protected by Copyright, and permission should be obtained from the publisher prior to any
prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic,
mechanical, photocopying, recording, or likewise. For information regarding permission(s), write to
Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.
3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05

What did you learn?
1. Describe how organisms are built from cells.
2. What are the five groups of vertebrates?
3. What are adaptations? Give an example
of one.
4.

Plants can be vascular or
nonvascular. Describe on your own paper
how they differ. Include details from the
book to support your answer.

5.

Compare and Contrast Think about
crocodiles and alligators. How are they
similar? How are they different?

by Laura Johnson


The Building Blocks
of Living Things
Think about the building blocks you played with
when you were younger. You started with just one block.
If you put a few blocks together, you could build a
house. If you put many blocks together, you could build
something complicated, like a castle with towers. All
living things—plants and animals—are made of cells.

A cell is the smallest unit of a living thing. You can
think of cells as building blocks. Some living things
are made of just one block, or cell. Most plants and
animals are made by putting thousands, millions,
or even billions of cells together.
Cells can have many jobs. Some cells help a
living thing to be healthy. Other cells help
it to adapt to its environment.
Microscopes make objects appear
larger than they really are. By looking
at cells under a microscope,
scientists can see inside
them and learn how
they work.

blood cell

2

nucleus
cytoplasm

nucleus

chloroplasts

cell wall

membrane

animal cell

plant cell

The Parts of a Cell
Cells have different parts, and each part has a
specific job to do. The nucleus is like the “brain” of
the cell. The instructions for the cell’s job are stored
in the nucleus.
The cell membrane is a thin covering all around
the cell. It has two jobs. It separates the cell from
things around it. It also acts as a guard that decides
what can come into and go out of the cell.
Cytoplasm holds everything a cell needs to carry
out its life processes. It is a material similar to jelly that
fills the cell. The nucleus floats in the cytoplasm.
Plant cells have the same parts as animal cells—
plus some extras. The cell wall is outside of the cell
membrane. The walls of all the cells help hold up a
plant. Chloroplasts are the parts of a cell that trap
energy from sunlight so a plant can make its own food.

3


From Cells to Organisms
Cells have different shapes, depending on the kinds
of jobs they do. For example, nerve cells are very thin.
They act like wires that send messages through the
body. Nerve cells can be as long as your arm or

as short as the period at the end of this sentence.
Cells that look alike and have the same shape do
the same job. These cells combine to build tissue.
For example, nerve tissue is made of nerve cells.
Tissues of the same type combine to form organs.
For example, the brain is an organ that is made of
nerve tissue.

nerve cell

nerve tissue

Organs that work together form an
organ system. Two organs—the brain
and the spinal cord—build the central
nervous system in your body.
An organism is the complete
living thing that is made when
all the parts are combined.
An organism is made of
many cells. Unlike an
organism, a virus is a very
tiny particle with similarities
to both living and nonliving
things. It uses plant and
animal cells to make more
viruses.

brain
central nervous system

4

5


Kingdoms—The Largest Group

Sorting Living Things
Into Groups
There are more than a million organisms. Who
keeps track of them all? Biologists! In order to identify,
compare, and study all these organisms, biologists use a
classification system. Using this system, they place every
kind of organism into a group. All the organisms in a
group have common characteristics.
Biologists would ask questions like these to help them
decide if a shark and a dolphin belong in the same group.
Do sharks and dolphins have one cell or many cells?
They have many cells. That is a common characteristic,
so they belong in the same group.
Where do sharks and dolphins live? They live in the
ocean. That is another common characteristic, so they
still belong in the same group.
How do sharks and dolphins get oxygen? Sharks get
oxygen from the water. Dolphins get oxygen from the
air. That is a different characteristic, so they belong in
different groups.

6

Kingdoms are the largest groups in the
classification system. Many scientists divide
organisms into six kingdoms. The kingdom that
an organism belongs to depends mostly on how
many cells it has, what cell parts it has, where it
lives, and how it gets its food.

The Six Kingdoms of Living Things
Kingdom

Number of Cells

Cell Parts

Habitat

Food Source

Ancient
Bacteria

one cell

no separate
nucleus

land or water

make their

own food

True Bacteria

one cell

no separate
nucleus

land or water

some kinds get
food; some make
their own food

Protists

usually one cell

have a nucleus
and other cell
parts

water and damp
places on land

many get food;
some make
their own

Fungi

usually many cells

have a nucleus
and other cell
parts

land

get food

Plants

many cells

have a nucleus
and cell wall

land and water

make their
own food

Animals

many cells

have tissues,
organs, systems

land and water

get food

7


Dividing the Kingdoms

How Living Things Are Classified

Sorting living things into six kingdoms is only the
beginning! Next, scientists divide the members of each
kingdom into smaller and smaller groups. They use
organisms’ features to decide which organisms are in
each group. After kingdoms, the groups are divisions,
classes, orders, and families. The last two groups are
genus and species. Scientists use these last groups to
name animals. A genus is a group of animals that are
similar in many ways. For example, a dog and a wolf are
members of the same genus. Their genus is Canis. The
genus group is divided one more time into groups of
species. A species is a group of animals whose members
can reproduce. The species name often describes where
the animal lives or what color it is.
The first part of an animal’s scientific
name is the genus. The second part is the
species. So, although you might name
your pet dog Max, his

scientific name would
be Canis familiaris.

At the right of the chart is the kingdom, the
largest group to which your family dog belongs.
The groups get smaller and smaller, and more
and more specific, until the final two
groups, which form the animal’s
scientific name.

SPECIES

8

GENUS

FAMILY

ORDER

CLASS

DIVISION

KINGDOM

9


How Scientists

Classify Plants
To sort plants into groups, scientists look at two main
characteristics. One is the way that a plant transports
water and nutrients. The other is how a plant reproduces.

Moving Water and Food
Some plants, called vascular plants, have parts that
look like tubes. Water and nutrients from the soil
move up and down these tubes to the roots, stems, and
leaves. Vascular plants are all around you. You may have
stepped on some this morning, if you walked on grass.
If you had celery with your lunch, you ate one! The
tissue that makes up the tubes supports a plant’s stems
and leaves. Because of this, vascular plants can grow to
be very tall.
moss

10

Plants without these tubes are called
nonvascular plants. These plants pass water
and nutrients through cell walls, from one
cell to the next. This process is very slow, so
nonvascular plants usually grow close to the
ground. That way, water and nutrients do
not have to travel so far. Some nonvascular
plants are mosses, lichen, and algae.

Reproduction

seed

The second way that scientists
classify plants is by how they
reproduce, or make new plants.
One group reproduces by making
seeds. A seed is a structure with
a protective covering. Inside the
seed is a young plant. In plants with
flowers, the seeds are in the flowers.
Conifers are plants that make seeds
but do not have flowers. In conifers,
the seeds are in the cones.
Some plants have no seeds at all. They
use spores to reproduce. A spore is a single
cell surrounded by a cell wall. It can grow
into a new plant if it falls on a place where
it can get the water and food it needs. Ferns
and mosses have spores.

11


How Scientists
Classify Animals
The animal kingdom is divided into two main
groups. One group is vertebrates, or animals with
a backbone. The other group is invertebrates, or
animals without a backbone.

Vertebrates
Scientists have divided vertebrates into five smaller
groups. This chart shows the characteristics that are
true for most of the vertebrates in each group.

Vertebrate

Covering

Breathing

Birth

mammals

hair or fur

lungs

live birth

birds

feathers

lungs

hatch from eggs

reptiles

scales

lungs

live birth or hatch from eggs

amphibians

wet skin

lungs or gills

hatch from eggs

fish

scales

gills

most hatch from eggs

Reptiles
Let’s take a closer look at one group of vertebrates—
reptiles. Reptiles include lizards, snakes, turtles,
crocodiles, and alligators. These animals live in the water
and on land. As you can see from the chart, reptiles
breathe air with their lungs. Many people are very
surprised when they touch a reptile for the first time.

They expect them to be wet and slimy, but they have
dry skin covered with scales.
People often confuse crocodiles and alligators
because the bodies of these reptiles are similar in many
ways. An easy way to tell them apart is to look at their
mouths. You can see a crocodile’s teeth when its mouth
is shut, but you cannot see an alligator’s
teeth in that position.

alligator

crocodile

12

13


The Life Cycle of a Reptile
Sea turtles spend most of their time underwater,
where they swim, sleep, and eat. Like all reptiles,
they have to come to the surface to breathe air
with their lungs. If they are swimming, they
need to come up for air about every five or ten
minutes. However, if they are asleep, they can stay
underwater for hours. Male sea turtles rarely come
on land, but female sea turtles come on land about
six times each nesting year to lay their eggs.

A female sea

turtle lays her
eggs on land.

The turtles grow to
be adults who will
reproduce.
Baby turtles hatch from the
eggs between forty-five and
seventy days later, and they
make their way to water.

14

Scientists are not sure how old
female sea turtles are when they
nest for the first time. But they do
know that they swim back to the
same area where they were hatched
as babies—even if that place is
miles and miles away.

15


bee

Animals Without
A Backbone

Animals without a backbone are called

invertebrates. You might be surprised to learn that
most animals in the world are invertebrates.
Arthropods are the largest group of invertebrates.
This group includes ticks, spiders, bees, shrimp,
scorpions, and centipedes. At first, these animals seem
very different because some swim, some fly, and some
crawl. However, they have two common characteristics
that cause scientists to group them together. The
first characteristic is that all arthropods have legs
and a body that are divided into sections. The
second is that all arthropods are covered with
a lightweight, hard skin that protects them.
This hard skin is called an exoskeleton.

The second largest group of invertebrates are
mollusks. This group includes scallops, oysters, squid,
and snails. Mollusks have soft bodies. Some have a
hard shell and some don’t. Most mollusks live in water,
but some live on land in damp places. Most mollusks
are only a few inches long,
but a few kinds are huge!
squid
Giant clams, for example,
can grow to more than four
feet long and weigh more than
five hundred pounds!
scallop

centipede

16

17


The Life Cycle
Of a Mollusk
When octopuses are ready to mate, the
male fertilizes the female’s eggs. The female
attaches the fertilized eggs to a rock or places
them in a hole. Over the course of several days,
a female may lay more than 100,000 eggs! If
the female has laid her eggs in a hole, she will
often seal up the hole to protect the eggs
and ensure that they are not harmed.
Females guard the eggs constantly.
Depending on temperature, the eggs
hatch anytime between four weeks
and seven months later. A short
time after the baby octopuses
emerge from their eggs, the
female octopus dies.
When the baby octopuses
emerge from their eggs, they
float to the top of the water.
They stay there until they
grow larger and can return
to the bottom of their
water habitat.
eggs

18

adult
octopus

baby octopus

19


Animal Adaptations
Adaptations are physical features or behaviors
passed on from parents. Adaptations help animals get
food, protect themselves, move, and reproduce. Animals
with the best adaptations have a better chance at getting
the resources they need, so they have a better chance
of reproducing.

Chemicals are another kind of adaptation. Some
chemicals give animals a nasty smell or taste so other
animals won’t eat them. Others poison their victims.
An octopus can use its sharp teeth to drill a hole in a
clamshell. It then injects poison through the hole. After
the clam is poisoned, its shell can be opened easily.

Adaptations That
Help and Protect
Many animals have physical adaptations that help
them move. Did you know that birds have hollow bones

to make them lighter? Did you know that fish have bags
of air in them that help them float? Or that flamingoes
have long necks so they can submerge their heads in
water and find food in the muddy bottom? What about
snails? They have a flat foot that oozes a sticky liquid.
They move by sliding along paths of their own slime.
Shapes and colors can provide protection by making
animals nearly invisible. When the long, thin razor
fish holds itself straight up and down in the water,
it looks like a piece of floating grass.
Features such as claws, tusks, and
horns protect some animals.

20

sharp
teeth

21


Animal Instincts
Instincts are behaviors that are inherited from
parents. These natural behaviors tell young animals how
to move, how to hide, and how to catch food. They will
remember these things all their life. Remember the baby
turtles that find their way to the sea? That is an instinct.

Another natural behavior that
does not need to be learned is

hibernation. Some kinds of mammals,
reptiles, and amphibians hibernate, or
become inactive, when the weather is
very cold and food is hard to find.
Chipmunks, for example, eat a
lot in the fall. The food is stored as
body fat that gives them energy during
winter, when they hibernate. They
don’t sleep straight through the winter
but wake for short periods to move
around and snack on saved food.

Animals Learn

Migration and Hibernation
Migration is an instinct. Many animals migrate
to find food as seasons change. Arctic terns leave the
Arctic Ocean in the fall, when the ocean begins to freeze
and fish are scarce. They fly to Antarctica, where fish
are plentiful. In the spring, when the ice in the Arctic
Ocean begins to melt, the terns fly home to nest.

Not all animal behaviors are
instincts. Many animals learn
behavior from their parents. Mother
bears teach their cubs to fish. And
wolves have a way of teaching their
young to avoid traps!
All living things, from the
smallest cell to the largest organism,

can be classified. Knowing the
classification of living things gives
us information about what they are
made of and how they adapt.
hibernating frog

22

23


What did you learn?

Vocabulary
cell
Glossary
chloroplast
cytoplasm
genus
cell
invertebrates
nucleus
chloroplast
species
vertebrates

the smallest unit of a living thing
the part of a plant cell that traps
energy from sunlight so the plant
can make its own food

cytoplasm

the substance in a cell that contains
what the cell needs to carry out its
life processes

genus

a group of closely related animals

invertebrates

animals without a backbone

Picture Credits
Every effort has been made to secure permission and provide appropriate credit for photographic material.
The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions.

nucleus

the control center of a cell

Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd).

species

a group of animals whose members
can mate

vertebrates

animals with a backbone

Opener: (B) Bryan F. Peterson/Corbis, (C) Frans Lanting /Minden Pictures; 4 (BR) Science Photo Library/
Photo Researchers, Inc.; 8 (CR) Mary Ann McDonald/Corbis (CB, CRB) ”Jerry Young/DK Images;
9 (CL, CR, C, C1) Mary Ann McDonald/Corbis, (CLB, CBL, CBR, CRB) ”Jerry Young/DK Images, (CA, CAR, CRA) ”Barry Watts/
DK Images; 13 (CR) Bryan F. Peterson/Corbis, (BR) Frans Lanting /Minden Pictures; 18 (BR) Fred Bavendam /Minden Pictures;
19 (T) Ken Lucas/Ardea, (BC) Fred Bavendam/Minden Pictures; 22 Kennan Ward/Corbis.
Unless otherwise acknowledged, all photographs are the copyright © of Dorling Kindersley, a division of Pearson.

ISBN: 0-328-13860-6
Copyright © Pearson Education, Inc. All Rights Reserved. Printed in the United States of America.
This publication is protected by Copyright, and permission should be obtained from the publisher prior to any
prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic,
mechanical, photocopying, recording, or likewise. For information regarding permission(s), write to
Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.
3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05

24

1. Describe how organisms are built from cells.
2. What are the five groups of vertebrates?
3. What are adaptations? Give an example
of one.
4.

Plants can be vascular or
nonvascular. Describe on your own paper
how they differ. Include details from the

book to support your answer.

5.

Compare and Contrast Think about
crocodiles and alligators. How are they
similar? How are they different?