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Table of Contents
Georgia Performance Standards Correlation Chart . . . . . . . . . . . 7
Georgia Performance
Standards
Chapter 1
Lesson 1
Cells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Cell Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
SB1.a
Lesson 2
Transport and Homeostasis . . . . . . . . . . . . . . . . . . . . 18
SB1.a, d
Lesson 3
Structure and Function of Macromolecules . . . . . . . . 23
SB1.c
Lesson 4
The Role of Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . 28
SB1.b
Chapter 1 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Chapter 2
Lesson 5
Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Energy in Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
SB3.a
Lesson 6
Comparing Organisms. . . . . . . . . . . . . . . . . . . . . . . . . 44
SB3.b, c; SCSh7.c–e
Lesson 7
Prokaryotes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
SB1.a; SB3.b
Lesson 8
Eukaryotes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
SB1.a; SB3.b
Lesson 9
Viruses and Living Things . . . . . . . . . . . . . . . . . . . . . . 56
SB3.d
Chapter 2 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
SB2.a, b; SCSh8.f
Lesson 11
The Structure and Role of RNA . . . . . . . . . . . . . . . . . . 69
SB2.a, b
Lesson 12
Mendelian Genetics . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
SB2.c; SCSh5.e; SCSh8.a
Lesson 13
Meiosis and Genetic Variation . . . . . . . . . . . . . . . . . . . 81
SB2.c
Lesson 14
Mutations and Genetic Variation . . . . . . . . . . . . . . . . . 86
SB2.d
Lesson 15
Sexual and Asexual Reproduction . . . . . . . . . . . . . . . 90
SB2.c, e
Lesson 16
DNA Technology and Genetic Engineering . . . . . . . . . 93
SB2.f
Chapter 3 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Chapter 4 Ecology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Lesson 17 Ecological Organization . . . . . . . . . . . . . . . . . . . . . . . 104
SB4.a; SCSh8.f
Lesson 18
Relationships among Organisms. . . . . . . . . . . . . . . . 109
SB4.a; SCSh3.d, e
Lesson 19
Energy Flow in Ecosystems. . . . . . . . . . . . . . . . . . . . 113
SB4.b
Lesson 20
Biogeochemical Cycles . . . . . . . . . . . . . . . . . . . . . . . 117
SB4.b
Lesson 21
Ecosystem Changes and Succession . . . . . . . . . . . . 122
SB4.c
Duplicating any part of this book is prohibited by law.
Chapter 3 Genetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Lesson 10 The Structure and Role of DNA. . . . . . . . . . . . . . . . . . 64
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Lesson 22
Human Causes of Environmental Change . . . . . . . . 126
SB4.d
Lesson 23
Plant Adaptations . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
SB4.e
Lesson 24
Animal Adaptations . . . . . . . . . . . . . . . . . . . . . . . . . . 137
SB4.f
Chapter 4 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Chapter 5 Evolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Lesson 25 Darwin and Evolutionary Theory . . . . . . . . . . . . . . . . 150
SB5.a, b, d; SCSh7.b, c, e
Lesson 26
Patterns, Processes, and Rates of Evolution . . . . . . 155
SB5.b, c
Lesson 27
Evidence for Evolution . . . . . . . . . . . . . . . . . . . . . . . . 160
SB5.c
Lesson 28
Natural Selection and Changes in Organisms. . . . . . 166
SB5.d, e
Chapter 5 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Investigation 1 Investigating Osmosis . . . . . . . . . . . . . . . . . . . . . 175
SCSh1.c;SCSh2.a–c;
SCSh3.a, c, e; SCSh4.a;
SCSh6.a; SCSh7.a–c;
SB1.a, d
Investigation 2 Exploring Tropisms . . . . . . . . . . . . . . . . . . . . . . . 185
SCSh1.a; SCSh3.a, c, e, f;
SCSh6.a, c; SCSh7.d;
SCSh8.a, b, c; SB4.e
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Pretest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Duplicating any part of this book is prohibited by law.
Posttest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
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Chapter 1 • Lesson 2
Standard: SB1.a, d
Transport and Homeostasis
Key Words
• homeostasis • diffusion • passive transport • equilibrium • selectively permeable • osmosis
• concentration gradient • hypertonic • hypotonic • isotonic • facilitated diffusion
• active transport • endocytosis • exocytosis
Getting the Idea
In Lesson 1, you learned that every cell is enclosed in a cell membrane. The membrane
defines the cell, by separating it from its environment. The cell membrane is also
essential to the cell’s life processes because it regulates what materials enter and
leave the cell. In this way, the cell membrane serves as a means of transport and helps
maintain homeostasis.
The Cell Membrane and Homeostasis
A cell membrane is usually made up of two layers of lipids, oily or waxy organic
molecules that tend to repel water. This structure is known as a lipid bilayer. As shown
below, most cell membranes also contain protein molecules within the lipid bilayer.
Many of these proteins are attached to carbohydrates.
Cell Membrane
Carbohydrate chain
Protein
Lipid bilayer
The cell membrane helps maintain homeostasis by regulating what materials enter and
leave the cell. Homeostasis is the ability of a cell or organism to maintain stable internal
conditions despite changes in its environment. The stable internal state is also called
homeostasis. This balance allows cells to survive and function properly.
Diffusion
Cells have to take in nutrients to carry out the functions needed to sustain life. They must
also release wastes. One way materials enter and leave a cell is by diffusion. Diffusion
is the movement of particles from an area of higher concentration to an area of lower
concentration. In other words, the particles travel from areas where they are crowded to
areas where they are less crowded.
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Protein channel
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Particles in solutions, such as those inside and outside a cell membrane, are in constant motion.
The particles constantly collide with each other and tend to spread out randomly. Diffusion
depends on the random movements of particles, so it does not require a cell to use energy.
The movement of materials into or out of the cell without the expense of energy is called
passive transport.
Particles continue to diffuse into or out of a cell until their concentration is the same on both
sides of the cell membrane. When particles reach this state of equal concentration, the system
is at equilibrium. Once equilibrium is reached, particles continue to diffuse across the cell
membrane in both directions. However, the same numbers of particles move in each direction,
so the concentration does not change.
Osmosis
Not all particles can diffuse across a cell membrane. A membrane is permeable to substances
that can pass through it and impermeable to those that cannot. Cell membranes are selectively
permeable, that is, they allow only some particles to pass through them.
Living cells are made up mostly of water. Water is an excellent solvent. A solvent is a substance
in which other substances, or solutes, dissolve to form a solution. Many different compounds
dissolve in water. In fact, cytoplasm is made up mostly of substances dissolved in water.
For these reasons, water may be the most important substance that passes through the
cell membrane.
Water molecules pass through selectively permeable membranes by a type of diffusion known
as osmosis. Osmosis is the movement of water molecules from a place of higher concentration
to a place of lower concentration—either into or out of the cell. The diagram illustrates the
movement of water molecules across a membrane by osmosis.
Dilute sugar
solution
Concentrated
sugar solution
Sugar
molecules
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Selectively
permeable
membrane
Water
movement
A difference in concentration on opposite sides of a cell membrane makes osmosis possible.
This difference is known as the concentration gradient. When there is a concentration gradient
between a cell and its surroundings, the outside solution is either hypertonic or hypotonic.
In a hypertonic solution, the concentration of solute outside the cell is higher than the
concentration in the cytoplasm. When a cell is placed in a hypertonic solution, water moves out
of the cell. This movement of water causes the cell to shrivel.
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In a hypotonic solution, the concentration of solute in the cytoplasm is higher than that outside
the cell. When a cell is placed in a hypotonic solution, water moves into the cell. This causes the
cell to swell and possibly burst.
Solutions with equal concentrations on both sides of a membrane are isotonic. As shown
below, a cell is in a balanced environment when placed in an isotonic solution. Equal amounts
of water move into and out of the cell.
The Effect of Osmosis on Cells
Solution
Isotonic:
Animal Cell
Plant Cell
Water in
Water in
The concentration of
solutes is the same
inside and outside
the cell.
Cell membrane
Cell wall
Water out
Water out
Hypertonic:
Solution has a higher
solute concentration
than the cell.
Hypotonic:
Solution has a lower
solute concentration
than the cell.
Water out
Water out
Water in
Water in
Facilitated Diffusion
Recall that cell membranes have protein channels, that is, protein molecules embedded in
the lipid bilayer. Each protein channel helps a specific type of molecule enter or leave the
cell. Protein channels in red blood cells, for example, carry only glucose. Although the protein
channel helps glucose move across the cell membrane, the process is still diffusion. It occurs
only if there is a difference in concentration on the two sides of the cell membrane.
Facilitated Diffusion
Glucose molecules
Protein channel
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Some molecules move through the cell membrane via facilitated diffusion (also called facilitated
transport). Facilitated diffusion is the movement of substances across a cell membrane with
the aid of carrier molecules embedded in the membrane. Facilitated diffusion allows specific
molecules to pass through the cell membrane more easily.
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Lesson 2: Transport and Homeostasis
Active Transport
Recall that the movement of materials across a cell membrane by diffusion and osmosis does
not require energy because materials are moving from an area of higher concentration to an area
of lower concentration. In some cases, materials must be moved into or out of a cell against the
concentration gradient from an area of low concentration to an area of high concentration. This
type of movement requires energy and is called active transport.
Like facilitated diffusion, active transport can use protein channels to move particles across the
membrane. The substance being transported binds to the channel proteins. One example of this
is the sodium-potassium pump. Sodium ions (Na +) are pumped out of the cell, and potassium
ions (K+) are pumped into the cell, by specific channel proteins. The cell uses energy to move
these ions.
Endocytosis and Exocytosis
Some large molecules are transported by movements of the cell membrane itself. Endocytosis
is a process in which a cell surrounds and takes in material from its environment. In endocytosis,
the cell membrane folds and then forms a pocket enclosing some outside material. The pocket
then separates from the cell membrane and forms a vacuole in the cytoplasm. The formation of
this vacuole carries the material into the cell. As shown below, organisms called amoebas use
endocytosis to feed.
Food being engulfed
by endocytosis
Food vacuole
Nucleus
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Cells use the opposite process, exocytosis, to remove unwanted materials. During exocytosis,
the membrane of a vacuole can fuse with the cell membrane. The contents of the vacuole are
removed from the cell. Some organisms, such as amoebas and paramecia, release water in
this way. Endocytosis and exocytosis are both forms of active transport.
Discussion Question
What are the advantages and disadvantages of endocytosis and exocytosis compared to other forms of
cell transport?
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Lesson Review
1.
Which of these terms describes the movement of water through a cell membrane?
A. osmosis
B. metabolism
C. homeostasis
D. active transport
2.
Which type of cellular transport requires a cell to use energy?
A. facilitated diffusion
B. active transport
C. osmosis
D. movement of glucose along a concentration gradient
3.
In which type of cellular transport are Na + and K + moved through a cell membrane?
A. facilitated diffusion
B. active transport
C. diffusion
D. osmosis
If an animal cell were placed in a solution of water taken from the ocean, what would
immediately happen to the cell?
A. The cell would swell because the ocean water is hypotonic.
B. The cell would swell because the ocean water is hypertonic.
C. The cell would shrivel because the ocean water is hypotonic.
D. The cell would shrivel because the ocean water is hypertonic.
Duplicating any part of this book is prohibited by law.
4.
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