Download Cells and Organisms

Cells and Organisms
Reading 1
Science
Reading
Strategy
Find the Main Idea
and Details What
is the topic of this
chapter? How are the
pictures related to this
topic?
✓
Reading Check
1.Recall details
Do you know what a dog, a tree, and a person have in
common? They are all organisms, or living things, made of tiny
cells. These cells work together to keep things alive.
What does the
big picture show?
What do the small
pictures show?
2.Make connections
How do the small
pictures relate to
the big picture?
have in common share something alike
Unit 1 • Chapter 2
37
The Cell
Reading
Strategy
Find the Main Idea
and Details Which
details on this
textbook page seem
important to you?
How do you know
they are important?
FOCUS QUESTION
What one part do all cells have?
1
1 cell
A (plant) cell
2 cytoplasm
3 cell membrane
4 chloroplast
5 vacuole
2
6 nucleus
7 endoplasmic
reticulum
6
7
3
8
8 ribosome
9 Golgi complex
10 lysosome
4
9
5
10
11 mitochondria
12 cell wall
11
12
Word Study
boxed item
Multiple-Meaning Words
The word cell has different meanings.
A cell is “a small room
locked from the outside.”
People in jail are kept
in cells.
A cell is the “basic unit of
living things.”
Your body is made up
of many cells.
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38 Unit 1 • Chapter 2
Reading
Strategy
Vocabulary in Context
All living things are made up of one or more cells.
Cells are the smallest unit of life. All cells have a cell
membrane. It controls what moves into and out of a
cell. Most cells have other parts, such as a nucleus,
vacuoles, ribosomes, and lysosomes. The nucleus
controls all activity in the cell. Vacuoles store water,
food, and waste. Ribosomes build proteins. Lysosomes
break down, or digest, material.
Find the Main Idea
and Details What is
the main idea of this
paragraph? Identify
two details that
support this idea.
1
An (animal) cell
2
caption
3
5
illustration
7
6
8
11
10
9
Check Your Understanding
1. Look at the plant cell and animal cell.
Name five parts that both cells have.
2. What does the nucleus do?
3. What one part do all cells have?
Critical Thinking Making Inferences
4. Why do cells have many different parts?
23
✓
Reading Check
1.Use text elements
What are two
meanings of the
word cell? Where
did you find the
information?
2.Identify details
What kinds of
cells are shown on
pages 22 and 23?
How do you know?
3.Make connections Name one thing
plant cells and
animal cells have in
common.
Unit 1 • Chapter 2
39
Multicellular Organisms
FOCUS QUESTION
What is a multicellular organism?
chapter title
1 cell
2 tissue
3 organ
4 organ system
Reading
Strategy
Lung cell
1
Find the Main Idea
and Details What
details in the diagram
support the main idea
of this page?
Trachea
Lung
2
3
Lung tissue
4
Respiratory system
Word Study
Word Parts
Multicellular is made up of two word parts.
The prefix multi can mean “much” or “many.”
The word cellular can mean “made of cells.”
30
40 Unit 1 • Chapter 2
A multicellular animal is made up of many cells.
Vocabulary in Context
Trees, people, and many other living things are made
up of many cells. They are multicellular organisms.
Groups of the same kind of cell form tissues. All the cells
in a tissue do the same kind of work. For example, lung
tissue helps you breathe. Tubes in plant stems carry things
between the roots and leaves. Those tubes are a tissue.
Two or more different tissues that work together form
an organ. A lung is an animal organ. A leaf is a plant
organ. Several organs that work together form organ
systems. For example, your lungs form part of your
respiratory system. The leaves, stems, and flowers on
a plant are in the plant’s shoot system.
Leaf cell
1
Reading
Strategy
Find the Main Idea
and Details What is
Flowers
the main idea of this
text? What is the main
idea of the diagram?
How do the text and
the diagram help
you to understand
the main idea of the
page?
Shoot
system
4
3
Stem
2
Leaf tissue
Roots
Leaves
✓
Reading Check
Check Your Understanding
1. Look at the pictures. What are tissues made of?
1. D
efineAnswer
2. Give two examples of organs. Give two examples
of organ systems.
question 3 in
the “Check Your
Understanding” box.
3. What is a multicellular organism?
Critical Thinking Comparing and Contrasting
4. How are tissues different from organs?
31
2. Use text elements Where did you
find the answer
to question 3 in
the “Check Your
Understanding”
box?
photograph
3. C
ompare How
is the respiratory
system of an
animal similar to
the shoot system of
a plant?
Unit 1 • Chapter 2
41
section
Multicellular Organisms
Kinds of Animal Cells
Multicellular animals contain many different kinds of cells.
Each kind of cell has a certain job. No other kind of cell can do
that job. For example, red blood cells collect gases in the lungs.
White blood cells protect the body against disease. They cannot
collect gases in the lungs.
bold term
table
Kind of Cell
What does this kind of cell do?
cardiac
muscle cell
The heart is made up of cardiac muscle cells. This kind of cell
causes the heart to beat.
skeletal
muscle cell
Skeletal muscle cells are connected to bones. This kind of cell
forms tissues that help move bones.
smooth
muscle cell
This kind of cell forms organs that help move food in the digestive
system. It also lines blood vessels and the airways of the lungs.
bone cell
The skeleton is made up of bone cells. This kind of cell provides
support and allows the body to move.
skin cell
This kind of cell protects the outside of the body from injury
and germs.
red
blood cell
This kind of cell carries gases to other cells in the body.
white
blood cell
This kind of cell fights disease in the body. White blood cells hunt
and eat germs and bacteria.
Animal Cells and Their Jobs
Reading
Strategy
Science Skill
A table presents information in rows and columns.
Sometimes a table will present details. Details are small,
important pieces of information.
1. Which two cells help protect the body? Which two cells help
the body move?
2. What are three jobs that muscle cells have in the body?
3. Which cell causes the heart to beat?
Find the Main Idea
and Details Answer
the “Science Skill”
questions about
details in the table.
Based on your
answers, what is
the main idea of this
page?
42 Unit 1 • Chapter 2
Looking for Details
32
How Cells Divide
Reading
Strategy
Cell division is the way an organism makes new cells or
repairs an injury.
First, the cell copies its chromosomes. Chromosomes are in
the cell’s nucleus. Chromosomes have information on how to
make new cells. Next, the two sets of chromosomes move away
from each other. Finally, the cell separates into two new cells.
Each new cell gets one set of chromosomes.
Find the Main Idea
and Details What
is the main idea
of this entire text?
What information on
this page helps you
understand the main
idea better?
Word Study
Phrasal Verbs
Phrasal verbs are made up of two or three words.
Move away from means “to go to a different place.”
Two sets of chromosomes move away from each
other when a cell divides.
Check Your Understanding
1. How do red blood cells help the body?
Cell Division
2. How do bone cells help the body?
questions
3. What are three important steps in cell division?
Critical Thinking Applying Information
4. You get a small cut. What do cells do to help your skin heal?
Research and Inquiry Use the internet, the library, or your
Writing Suppose you
science book to answer these questions.
fall and scrape your knee.
How do your white blood
cells help you heal? Write
a paragraph.
1. Why is the skin an organ system?
2. Why is an artiflcial heart not an organ?
3. How do skeletal muscles make bones move?
✓
Reading Check
1. R
ecall details 33
Answer question 1
in the “Check Your
Understanding”
box.
2. U
se text elements In what part of
the text did you
find the answer to
question 1?
3. Make an inference
When might an
organism have to
make new white
blood cells?
Unit 1 • Chapter 2
43