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Looking at Plants
and Animals
CHAPTER
Plants
. A2
CHAPTER 2
Animals
. A36
-
. ... —«
CHART
How Living Things
Are Alike, A4
The Needs of
Plants, A14
The Life Cycle
of a Plant, A24
Did You Ever Wonder?
How tall can a tree grow? The record is 112 meters
(368 feet). This is the height of a coast redwood, a
kind of pine tree found in Oregon and California.
Redwoods are some of the oldest and tallest trees.
How fast do you think a coast redwood grows?
What does it need to grow?
A2
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v.
,
n
I
Vocabulary
I
organism, A6
reproduction, A7
environment, A8
respond, A8
cell, AID
What do you see in this picture?
Some objects are living. Some
objects are nonliving. How can
you tell a living thing from a
nonliving thing?
Process Skill
"
You infer when you form
an idea based on facts or
observations.
A 4
Explore Activity
What Are the Features of
Living Things?
Materials
25 pea seeds
25 pieces of
gravel
(pea-sized)
hand lens
Procedure
2 plastic cups
Q Measure Place one teaspoon of pea seeds on
the white paper. Place one teaspoon of gravel
next to the pea seeds.
piece of white
paper
E3 Observe Look at the seeds and gravel with the
hand lens. Record your observations.
water
Q Mark a plastic cup A. Place the seeds in it.
Mark the other plastic cup B. Place the gravel
in it. Pour the same amount of water into each
cup. Make sure the seeds and gravel are
completely covered with water.
Q Predict What do you think will happen
after two days?
H Observe Look at the soaked seeds and
gravel every few hours for two days.
Record your observations.
Drawing Conclusions
Q What happened to the seeds?
What happened to the gravel?
Q Which is the living thing?
El Infer What are some features
of living things?
Q Going Further: Infer Are
you a living thing? How do
you know?
teaspoon
Read to Learn
Main Idea All living things have common features.
What Are the Features of Living Things?
An organism (AWR-guh-niz-uhm) is a living thing.
How can you tell an organism from a nonliving thing?
There are certain ways to tell a living thing from a
nonliving thing.
Living Things Grow and Change
A living thing grows. It starts out small. Then
it gets bigger. An oak tree begins as an acorn.
Then it grows to become a green sapling (SAP-ling).
This is a very young tree.
Organisms also change as they grow. The way
a living thing changes during its life is called
development (di-VEL-uhp-muhnt). As an oak sapling
grows, the branches and trunk become thicker and
stronger. The oak tree also changes its shape and
color as it develops.
Acorn
Green sapling
Diagrams
How does an oak
tree develop?
A6
..-
Large tree
r-
None of these puppies is an exact copy of its parents.
Each puppy has a mixture of features from both parents.
Living Things Reproduce
Another feature of living things is that they make
more of their own kind. Plants grow from seeds. Chicks
hatch from eggs. Some animals, such as puppies, are
born live from their mother. All these are examples of
reproduction (ree-pruh-DUK-shuhn). This is the
way organisms make more of their own kind.
How is a puppy similar to its parents? Some
new living things, or offspring, are not exact
copies of their parents. Instead, they have
characteristics of both parents. Most
animal offspring, including you, are not
exact copies of their parents.
What are two features of all
living things?
The offspring of a yellow tulip
and a red tulip is an orange tulip.
Red tulip
Orange
tulip
How Do Organisms React to Change?
All organisms live in an environment
(en-VIGH-ruhn-muhnt). An environment
is made up of everything that surrounds
an organism. It includes air, water, soil,
and other organisms.
Living Things Respond
When the environment changes, an
organism may respond (ri-SPAHND) to
that change. To respond is to react. All
living things respond to many changes.
As it prepares to sleep through
Both plants and insects respond to
the winter, a bear eats a great
light. Plants bend toward light. Insects
deal of food—including berries.
fly toward it. The leaves on some trees
respond to a change in season. In autumn they
How does a plant
turn colors, then fall off the branches. Animals
respond to the
also respond to a change in season. Bears eat
environment?
a lot of food as winter nears. Then they sleep
or rest through the winter in a cave.
You respond to your environment in many
ways, too. You may shiver if you are cold. What
other ways do you respond to changes in your
Sunflowers respond
by turning toward
environment?
the sunlight.
The cuttlefish changes
color to communicate.
How Do Living Things Communicate?
Most living things communicate (kuh-MYEW-ni-kayt),
which means to share information. To communicate,
organisms send, collect, and respond to signals.
How do living things communicate?
They communicate in many ways. Fireflies
flash lights to attract mates. Some birds
sing to mark the area where they live.
When a male red-wing blackbird
sings, it is saying to other males,
"Stay out of my territory!" The
cuttlefish changes skin color and
texture. This alerts other animals
that it is looking for food.
To receive communications, living things use
their senses. The senses of sight, smell, hearing,
and touch can all receive information.
When a red-wing
blackbird sings,
other male redwing blackbirds
know to keep
their distance.
What senses do living
things use to communicate?
A9
What Are the Smaller
Parts of Living Things?
More than 300 years ago, scientist Robert
Hooke looked at a thin piece of cork
through a microscope (MIGH-kruh-skohp).
A microscope is a device that uses glass
lenses, similar to those in eyeglasses. The
lenses allow people to see very small things.
Hooke saw that the cork was made of tiny
boxlike shapes that he called cells.
Cells are the basic building blocks of life.
Since Hooke's time scientists have learned
that all living things are made of cells. Your
own body is made of billions of cells.
Plant and animal cells have many of the
same parts. Both plant and animal cells are
filled with cytoplasm (SIGH-tuh-plaz-uhm).
Cytoplasm is a clear, jellylike material. Both
types of cells also have a cell membrane.
A cell membrane is the thin outer
covering of the cell.
Plant Cell
Cell membrane
Nucleus
These cork cells
are similar to
the ones Hooke
saw in 1665.
Chloroplast
Diagrams
Cell wall
What are the parts of a plant cell?
A 1O
Each cell also has a nucleus
(NEW-klee-uhs). The nucleus is
the control center of the cell.
In other ways plant cells are very
different from animal cells. Plant
cells are usually larger and have a
boxlike shape. Animal cells come in
a wide variety of shapes. A plant cell
also has a cell wall, which is a stiff
layer outside the cell membrane.
Animal cells lack cell walls.
Most plant cells have green
chloroplasts (KLAWR-uh-plasts).
Chloroplasts make food. Animal
cells do not have chloroplasts.
Animal Cell
F O R S C H O O L O R HOME
Know the Back
of Your Hand
I. Predict With a pen, make the
Nucleus
Cytoplasm
smallest dot you can on the
back of your hand. How many
cells do you think it covers?
2.
Use Numbers Place some
beans in a solid circle. This
circle represents the ink dot
on your hand. How many
beans do you have?
Cell membrane
This is an
animal cell.
3.
Interpret Data Each bean
represents a skin cell. How
many skin cells are under the
ink dot?
| Draw Conclusions
Why are cells called the basic
building blocks of life?
4.
How did your prediction
compare to this number?
A 11
Process Skill
6
U I I Dt *
Experiment
Materials
mealworm
How Does a Mealworm Respond to
Its Environment?
hand lens
In this activity you will experiment to find out how a mealworm
responds to changes in its environment.
toothpick
ruler
Handle animals with care.
Wash your hands after handling mealworms.
construction
paper
Procedure
El Observe Place the mealworm on the
paper. Look at it with the hand lens.
How does it move? Very gently, touch it
with a toothpick. Record your
observations.
0
To test how the mealworm responds,
plan several ways to change its
environment. Be sure the
changes will not harm the
mealworm. Record your
plans in a chart like the
one shown.
Q Experiment Test the
statements. Record the
results in your chart.
Drawing Conclusions
Write a paragraph that describes
how the mealworm responds
to changes in its
environment.
A 12
If Statement
Then Statement
Results
If something
then it will
change its path
gets in the
mealworm's path
If...
-/""^-^^^
then...
^~^
.
^^ ^
Lesson Review
Why It Matters
Living things grow and
change, reproduce, and
respond to their environment.
It is important to be able to
identify living things. Only
living things are made of cells.
Each cell in your body is a
living thing, but a cell cannot
live by itself. Each of your cells
must live as a part of a larger
living thing—you.
Think and Write
1 . What is an organism?
2.
How is a living thing
different from a nonliving
thing?
3* What features do all
animal and plant cells have
in common?
4* Experiment How would
you test the way a plant
may respond to changes in
its environment?
5. Critical Thinking What if
your pet dog lost its sense
of smell? How would this
change the way it responds
to its environment?
Write a narrative paragraph. Imagine
you are an underwater explorer. You find
something that looks like the picture above.
You are not sure if it is a living thing. How
can you find out? Describe your discovery.
MATH LINK
Solve a problem. How small do you think
a typical animal cell is? Look at the red
dash. You could line up more than 300 cells
along it. How many cells do you think you
could line up along the blue dash?
ART LINK
Create a poster. Make a poster that shows
an animal cell. Label all the parts.
TECHNOLOGY LINK
At the Computer Visit
www.mhscience02.com
for more links.
A 13