Name
Class
Date
Introduction to Genetics
Information and Heredity
Q: How does biological information pass from one generation to another?
Chapter Summary
The diagram below shows what you will read about in this chapter and how the chapter is
organized. Study the diagram. Then answer the questions that follow.
11.1 The Work of
Gregor Mendel
The experiments of Gregor Mendel
Segregation
Probability and Punnett squares
11.2 Applying
Mendel’s
Principles
Independent assortment
A summary of Mendel’s principles
11.3 Other Patterns
of Inheritance
Beyond dominant and recessive alleles
Genes and the environment
Chromosome number
11.4 Meiosis
Phases of meiosis
Comparing meiosis and mitosis
Gene linkage and gene maps
genetics
1. What is the main concept?
2. What are the four major topics? work of Mendel, applying Mendel’s principles, other
patterns of inheritance, and meiosis
3. What will you learn about in Lesson 2? probability and Punnett squares and
independent assortment
4. In which lesson will you learn about the differences between meiosis and mitosis?
Lesson 4
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11.1 The Work of Gregor Mendel
Lesson Objectives
Describe Mendel's studies and conclusions about inheritance.
Describe what happens during segregation.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Allele
Different form of a gene
An allele is an alternate form of a gene.
Fertilization
Process in which male and female
gametes join to produce a new cell
Fertile fields produce crops.
Fertilization produces a new organism.
Gamete
Cell used for reproduction; egg or
sperm
Guys and gals produce gametes.
Gene
Information about an individual’s
characteristics that is passed from
one generation to the next
A gene carries information from one
generation to the next.
Hybrid
Offspring between parents with
different traits
A hybrid car is a cross between a
gasoline and an electric car. A hybrid
organism is offspring from two
parents with different traits.
Principle of
dominance
Some alleles are dominant, and
others are recessive.
The principle of dominance states
that some alleles dominate over
others.
Segregation
Separation of alleles during
formation of sex cells
Segregation means to separate into
different groups; during segregation,
alleles separate into different gametes.
Trait
A specific characteristic of an
individual
My traits distinguish me from
everyone else.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
Note: Students should highlight terms and definitions used throughout the chapter.
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The Experiments of Gregor Mendel
Dominance Mendel’s principle of dominance states that some alleles are dominant and
others are recessive. An organism with a dominant allele will always show the dominant form
of the trait. An organism will only express the recessive form of a trait when a dominant allele
is not present.
In the space provided, fill in the genotype of the offspring. The first one is done for you.
Dominant and Recessive Forms of Pea Plant Traits
Trait
Offspring
(F1 Generation)
Parent Plants (P Generation)
Seed Color
Yellow
YY
Seed Coat Color
White
gg
Pod Shape
X
X
Constricted
ss
X
Green
YY
Yellow
YY
Gray
GG
Gray
Gg
Smooth
SS
Smooth
Ss
Answer the questions. Circle the correct answer.
1. What is the dominant shape of a pea pod?
constricted
smooth
2. What is the recessive color of a pea plant’s seed coat?
white
gray
BUILD Connections
Not Two of Kind An analogy takes two things that seem to be different and shows how
they can be similar. Visualize a hybrid car. Hybrid cars use two different sources of energy:
gasoline and electricity.
1. A hybrid is a cross, or a mixture, of two things. What is crossed in hybrid cars?
Sample answer: The type of energy used is crossed. In hybrid cars, the two forms of
energy used are gasoline and electricity.
2. Find a partner. Try to think of other things that are hybrids. Sample answers: dogs,
plants, creatures from myths, words
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BUILD Understanding
Two-Column Chart A two-column chart is a way to take notes about what you read. Copy
the chart shown below in your notebook. Leave space for all the headings in the lesson. As
you read the lesson, complete the chart. Write the main ideas in the left column. Use the
names of the headings in the lesson. Then, list details and examples that go with that heading
to the right column. An example has been done for you.
Main Ideas
The Experiments of
Details and Examples
Mendel worked with garden peas.
Gregor Mendel
The Role of
Mendel cross-pollinated pea flowers; studied seven traits of pea
Fertilization
plants.
Genes and Alleles
Mendel’s hybrids did not show the traits of both parents.
Mendel thought that an individual’s traits were due to factors
passed from parents to offspring.
Dominant and Recessive Alleles
Humans inherit alleles from their parents. Children who exhibit a dominant trait such as
freckles must receive the dominant allele from one of their parents.
Analyze and Conclude
The following table shows some dominant traits exhibited by Julia and her parents.
Julia’s Dad
Julia’s Mom
Julia
Freckles
yes
yes
yes
Cheek dimples
yes
no
yes
Free ear lobes
yes
no
no
Use the table to answer the questions.
1. Which statement is true about Julia and her parents? Circle the correct answer.
A. They all have at least one dominant allele for freckles.
B. They all have at least one dominant allele for cheek dimples.
C. They all have at least one dominant allele for free ear lobes.
2. In the future, Julia will marry a man with freckles. However, her daughter will not have
freckles. How is that possible? Julia and her husband each have one dominant allele
and one recessive allele for freckles. They passed the recessive alleles on to their
daughter.
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11.2 Applying Mendel’s Principles
Lesson Objectives
Explain how geneticists use the principles of probability to make Punnett squares.
Explain the principle of independent assortment.
Explain how Mendel’s principles apply to all organisms.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the chart
by writing a strategy to help you remember the meaning of each term. One has been done
for you.
Term
Definition
How I’m Going to Remember
the Meaning
Genotype
Genetic makeup
Heterozygous
Organism that has different
alleles for a gene
Homozygous
Organism that has two identical
alleles for a gene
Independent
assortment
Genes for different traits
segregate independently when
gametes are formed
Phenotype
Physical traits
Probability
The likelihood that a particular
event will occur
Punnett square
Diagram that can be used
to predict the offspring of a
genetic cross
Genotype is an organism’s set of genes.
Hetero- means “different.”
Heterozygous alleles are different.
Homo- means “same.” Homozygous
alleles are the same.
Independent means “not controlled.” When
gametes form, the distribution of alleles for
one gene is not controlled by the distribution
of alleles for another gene.
Phenotype is an organism’s physical
traits.
Probability has to do with chance.
Probability is the chance that an event
will happen.
Punnett square can be used to predict
offspring.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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BUILD Understanding
Preview Visuals You can use a KWL chart to preview a visual. Study the figure of
Segregation and Probability in your textbook. Write the information that you already know
about it in the left-hand column. In the middle column, write something you want to know
about the figure. After reading the section, write two things that you learned.
K
(What I know)
W
(What I want to know)
The two plants at the top of
the figure are peas.
Sample answer: What are
the circles in the center of
the picture?
L
(What I learned)
Sample answer: The circles in the center of the
picture represent alleles
of traits.
Probability and Punnett Squares
Follow the directions.
1. Table A lists some characteristic of pea plants. Write Ph in the right column if the
characteristic describes a phenotype. Write Ge if the characteristic is a genotype.
2. Table B lists some genotypes of pea plants. Write He in the right column if the genotype is
heterozygous. Write Ho if the genotype is homozygous.
Table A
Characteristic
Table B
Phenotype or
Genotype?
Genotype
Heterozygous or
Homozygous?
tall
Ph
RR
Ho
short
Ph
tt
Ho
Tt
Ge
Rr
He
TT
Ge
Tt
He
yellow seed color
Ph
YY
Ho
yy
Ge
Yy
He
Yy
Ge
Gg
He
rr
Ge
GG
Ho
gg
Ho
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Probability and Punnett Squares (continued)
In the space provided, fill in the missing genotypes. Write Tt or tt. In this example, T = tall and
t = short.
Tt
T
t
TT
T
Tt
Tt
t
Tt
tt
Answer the items.
1. Write the phenotypes of the three genotypes shown above.
TT
tall
tt
short
Tt
tall
2. If two heterozygous plants create four offspring, how many do you predict would be tall?
How many do you predict would be short? Sample answer: Three offspring will be tall
and one offspring will be short.
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11.3 Other Patterns of Inheritance
Lesson Objectives
Describe the other inheritance patterns.
Explain the relationship between genes and the environment.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Codominance
Both alleles show up in the
phenotype
Co- means share. Codominant traits share
importance in phenotype.
Incomplete
dominance
The heterozygous phenotype is
a blend of the two homozygous
phenotypes
Incomplete dominance means “not
fully dominant.” Therefore, both
phenotypes blend in heterozygotes.
Multiple allele
More than two alleles are
involved in a phenotype
Multiple alleles have more than two
alleles.
Polygenic trait
Involves the interaction of two
or more genes
Poly- means “many.” A polygenic trait
can involve many genes.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
BUILD Understanding
Main Idea and Details Chart A main idea and details chart can help you organize
information as you read. Copy the chart below in your notebook. On the left side of the chart,
write down the main topics. As you read, add details and examples that support the main ideas.
One example has been done for you.
Main Idea
Codominance
Details and Examples
Phenotypes of both alleles are expressed. Example: black and white
chickens
Check sudents’ charts to make sure that students have correctly identified main ideas and have supplied valid details.
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Beyond Dominant and Recessive Alleles
In incomplete dominance, the phenotypes of alleles blend. In codominance, the traits do not
blend. Instead, both alleles show up in the phenotype.
Unlike the genes for the traits that Mendel studied, some genes have more than one allele.
These genes have multiple alleles. And some traits are controlled by more than one gene.
These traits are called polygenic traits.
Follow the directions.
1. Use the colors pink, white, and red to demonstrate incomplete dominance in the flowers
of this genetic cross.
RR
R
WW
Students will color the RR flower
red, the WW flower white, and the
RW flowers pink.
R
RW
RW
RW
RW
W
W
Answer the questions.
2. A the gene for a rabbit’s coat color has four different alleles. Which of the following
statements is true? Circle the letter of the statement that is true.
A. In a population of rabbits, there can be two different coat colors.
B. In a population of rabbits, there can be four different coat colors.
C. One rabbit can have fur with four different colors.
D. Fur color in rabbits is a controlled by several different genes.
3. Eye color in humans is an example of a polygenic trait. Which of the following statements
is true? Circle the letter of the statement that is true.
A. A person always has the exactly the same eye color as one of his or her parents.
B. There are only three different eye colors in humans.
C. Eye color in a human population can occur in a wide range of shades.
D. Eye color in humans is controlled by one gene with several different alleles.
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Beyond Dominant and Recessive Alleles
4. Explain the difference between incomplete dominance and codominance.
In incomplete dominance, the heterozygous phenotype lies somewhere between the
two homozygous phenotypes. In codominance, the phenotypes produced by each allele
are clearly expressed in the heterozygous phenotype.
5. Circle the traits that are controlled by multiple alleles.
blood type in humans
tongue-rolling in humans
height in pea plants
dimples in humans
coat color in rabbits
skin color in humans
CHAPTER
Green Parakeets Offspring do not always look just like their parents. In the box
below, draw Susan’s two parakeets and their three offspring. Color each parakeet.
Check students’ drawings. The two parents should be green. One offspring
should be white, one blue, and one yellow.
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11.4 Meiosis
Lesson Objectives
Contrast the number of chromosomes in body cells and in gametes.
Summarize the events of meiosis.
Contrast meiosis and mitosis.
Describe how alleles from different genes can be inherited together.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Crossing-over
Exchange of DNA by the
chromatids in a tetrad
In crossing-over, tetrads cross their arms to
swap DNA.
Diploid
Two sets of chromosomes,
one from each parent
Haploid
One set of chromosomes
Homologous
Chromosomes in which one
set comes from the female
parent and one from the
male parent
Meiosis
Cell division in which
gametes are produced
Tetrad
A set of four chromatids
formed by two pairs of
replicated chromosomes
Zygote
Cell produced by the union
of egg and sperm
Di- means “two,” so a diploid cell has two
sets of chromosomes.
Haploid and half have the same beginning
sound, so a haploid cell has half as many
chromosomes as a diploid cell.
Homo- means “same,” and homologous
chromosomes are the same in size and
shape.
Meiosis produced gametes that resulted
in me.
Tetra- means “four” and a tetrad contains
four chromatids.
A zygote contains all of the parents’ genes,
from A to Z.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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BUILD Understanding
Compare/Contrast Table Use a compare/contrast table when you want to see the
similarities and differences between two or more objects or processes. As you read Lesson 1,
make a compare/contrast table to show the differences between mitosis and meiosis.
Use the terms or phrases to complete the compare/contrast chart. Write the terms or phrases
in the correct column.
Produces body cells
Produces gametes
Tetrads are formed.
Yields four haploid cells
Crossing-over occurs.
Yields two diploid cells
Involves two cell divisions
Mitosis
Meiosis
produces body cells
produces two diploid cells
produces gametes
produces four haploid cells
Tetrads are formed.
Crossing-over occurs.
Phases of Meiosis
During meiosis, haploid gametes are produced from diploid cells. At the end of meiosis, the
number of chromosomes in gametes is half the number of chromosomes in body cells.
Look at the diagrams below. Then use the words in the box to label the phases shown in the
diagrams.
Metaphase I
Anaphase II
Prophase I
Metaphase I
Prophase I
Anaphase II
Answer the question.
1. Suppose an organism’s heart cells have 10 chromosomes. How many chromosomes will
its egg cells have?
5
How many chromosomes does its sperm cells have?
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Chapter Review
Use the clues and words to help you write the vocabulary terms from the chapter in the
blanks. You may use a word once or not at all.
allele
gene
genetics
heterozygous
probability
genetics
1. the study of heredity
2. form of a gene
allele
3. factor that is passed from parent to offspring
gene
probability
4. the likelihood that a particular event will occur
Answer the following questions.
5. A male hamster has the genotype Dd and has straight fur. A female hamster has the
genotype dd and has curly fur. Complete the Punnett square to show the possible
offspring of these hamsters.
D
d
d
Dd
dd
d
Dd
dd
Use the Punnett square to answer questions 6 and 7. Circle the correct answer.
6. What is the probability that the hamsters’ offspring will have straight fur?
25%
50%
75%
100%
7. The owner of the female hamster wants offspring with curly fur. What genotype will a
male hamster need to have in order to produce only offspring with curly fur?
dd
Dd
DD
8. Explain the principle of dominance. Some alleles are dominant, and others are
recessive. If the dominant allele for a trait is present, it will be expressed. The recessive
allele will be masked.
9. Draw a flowchart showing the phases of meiosis I. Use the terms: telophase I, anaphase I,
prophase I, cytokinesis, metaphase I.
Prophase I
Metaphase I
Anaphase I
Telophase I
Cytokinesis
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Taking a Standardized Test
Test-Taking Tip: Study Diagrams and Labels
If a test question includes a diagram, look carefully at the diagram. Read all labels both before
and after you read the test question.
Read the following questions and answer choices.
T
T
t
t
Tt
Tt
tt
Examine the Punnett square above. The genotype in the blank box is
A. TT
B. Tt
C. tT
D. tt
Step 1 Examine the diagram. In this question, the diagram shows a Punnett square. Read
the labels. The genotype across the top of the Punnett square is Tt. The genotype on the side
is Tt.
Step 2 Read the question carefully.
Step 3 Look closely at the diagram again and read the labels. The question asks you to
determine the genotype that will be written in the blank. This offspring will inherit T from
both parents.
Step 4 Find the correct answer in the answer choices. The genotype will be TT. Choice A
is the correct answer.
Self-Test
Practice what you have learned by answering the following questions. Look closely at the
diagram before answering the question. Then circle the correct answer.
Use the diagram of the Punnett square in the sample question to answer question 1.
1. The letters in the boxes represent
A. phenotypes.
B. genotypes.
C. haploid chromosomes.
D. codominant alleles.
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Use the diagram to answer questions 2 and 3.
2. The first cell in the diagram contains
A. one pair of genes.
B. two pairs of segregated alleles.
C. one pair of gametes.
D. two pairs of homologous
chromosomes.
Meiosis I
3. According to the diagram, meiosis
results in
A. haploid cells.
C. identical cells.
B. diploid cells.
D. body cells.
Meiosis II
Use the Punnett square to answer questions 4 and 5.
R
R
W
RW
RW
W
RW
RW
4. Flowers with the genotype WW are white. Flowers with the genotype RR are red. What is
the genotype of each offspring?
A. RR
C. WW
B. RW
D. RRWW
5. Flowers with the genotype RW are pink. In these flowers, the inheritance of color
A. is affected by the environment.
B. is controlled by multiple alleles.
C. is an example of polygenic inheritance.
D. is controlled by incomplete dominance.
Short Response Question
Answer the following question in two or three sentences.
6. Rabbits can have curly ears or long ears. A homozygous curly-eared rabbit mated with
a homozygous long-eared rabbit. All the baby rabbits had long ears. Are long ears a
dominant or recessive trait? Explain your answer.
The trait is dominant because long ears show up in the first generation.
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DNA
Information and Heredity, Cellular Basis of Life
Q: What is the structure of DNA and how does it function in genetic
inheritance?
Chapter Summary
The diagram below shows what you will read about in this chapter and how the chapter is
organized. Study the diagram. Then answer the questions that follow.
Bacterial transformation
12.1 Identifying the
Substance of
Genes
Bacterial viruses
The role of DNA
The components of DNA
12.2 The Structure
of DNA
Solving the structure of DNA
The double-helix model
12.3 DNA
Replication
Copying the code
Replication in living cells
1. What is the main concept of this chapter?
DNA
2. What are the three major topics? identifying substances of genes, structure of DNA, and
replication of DNA
3. Can you predict what a double-helix is? Some students may know that a double helix
looks like a twisted ladder and describes the structure of DNA.
4. In which lesson do you think you will learn how DNA replication differs in prokaryotic
and eukaryotic cells?
Lesson 3
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12.1 Identifying the Substance of Genes
Lesson Objectives
Summarize the process of bacterial transformation.
Describe the role of bacteriophages in identifying genetic material.
Identify the role of DNA in heredity.
BUILD Vocabulary
A. The chart below shows the key terms in this lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
Bacteriophage
Type of virus that infects
bacteria
Transformation
When one type of bacteria
is changed permanently into
another type
How I’m Going to Remember
the Meaning
Bacteria are infected by bacteriophages.
To transform something means to change it into
something else.
Note: Students should highlight terms and definitions used throughout the chapter.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
CHAPTER
UV Light The most dangerous wavelengths of sunlight are ultraviolet rays, or UV rays.
They can damage skin and cause skin cancer. It is important to protect youself from
UV rays.
Make a poster showing how people can protect themselves from UV rays. Include
reasons why it is important to protect against the sun’s rays.
Students’ posters should include using
sunblock and moisturizers with SPF-15 or
greater, wearing hats and sunglasses, and
limiting time spent in the sun. They should
also list some of the risks, including skin
cancer.
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BUILD Understanding
Flowchart A flowchart is a way to show the steps in a process. As you read Lesson 1,
think about all the experiments that scientists performed to understand the job of DNA in
cells. Reflect on what scientists learned from each experiment. The three flowcharts below
summarize these experiments.
Complete each flowchart with a sentence that describes either the experiment or its results.
Researcher
Experiment
Some chemical
factor changed bacteria.
Griffith
Harmless bacteria
transformed into bacteria
that cause disease.
Removed carbohydrates,
lipids, proteins, from
heat-killed diseasecausing bacteria.
DNA is the molecule
that changed bacteria.
Labeled nucleic acids
in viruses with radioactive
isotopes of phosphorous-32.
The molecules that
viruses inject into
bacteria are nucleic
acids.
Avery
Hershey and Chase
Results
Bacterial Transformation
Answer the questions about Griffith’s experiment.
1. Griffith killed some disease-causing bacteria. He then mixed these dead bacteria
with harmless bacteria that were alive. When he injected this mixture of bacteria into
laboratory mice, what happened?
The mice got pneumonia and died.
2. After the experiment described above, what did Griffith conclude?
Griffith concluded that some chemical from the dead disease-causing bacteria entered
the harmless bacteria. The chemical then changed the harmless bacteria into bacteria
that caused pneumonia.
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Bacterial Transformation
The Hershey-Chase Experiment Hershey and Chase hoped to find out whether DNA or
protein carried the genetic information of a virus. The scientists used radioactive substances
to label the DNA in some viruses. They used the protein coat in other viruses. Then they let
the viruses inject their genetic material into bacteria.
Follow the directions.
1. Label the illustration that shows the bacterium that contains DNA with the radioactive label.
2. Label the illustration that shows the bacterium that contains DNA without the radioactive
label.
DNA with
radioactive label
Protein coat with
radioactive label
Phage infects bacteria
Phage infects bacteria
DNA with radioactive label
DNA without radioactive label
Answer the questions.
3. What did Hershey and Chase conclude was the genetic material of the virus? Circle the
correct answer.
DNA
protein
carbohydrate
4. What result did Hershey and Chase’s experiment have in the scientific community?
It convinced many scientists that DNA was the genetic material found in genes and
that it could be found in living cells as well as viruses.
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BUILD Connections
Passing Information An analogy takes two things that seem to be different and shows
how they are similar. The analogy below compares DNA with a book.
1. What do the book in the diagram and DNA have in common? They both carry coded
instructions.
2. Find a partner. Using the analogy, make a list of three things that DNA and a book have in
common. both store information; both can be copied; both transmit information
The Role of DNA
Storing Information The main job of DNA is to store genetic
information. Genes must have the information needed to produce
traits such as eye color or blood type.
Make a list of six things about this dog that are controlled by its DNA.
1.
height
2.
hair color
3.
eye color
4.
tail length
5.
ear length
6.
breed
Answers will vary.
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12.2 The Structure of DNA
Lesson Objectives
Identify the chemical components of DNA.
Discuss the experiments leading to the identification of DNA as the molecule that
carries the genetic code.
Describe the steps leading to the development of the double-helix model of DNA.
BUILD Vocabulary
A. The chart below shows the key term in this lesson with its definition. Complete the chart
by writing a strategy to help you remember the meaning of the term.
Term
Definition
How I’m Going to Remember
the Meaning
Base pairing
In DNA, cytosine pairs with
guanine, and adenine pairs
with thymine.
Base pairing explains the bases that pair
up in DNA.
B. As you work through this lesson, you may find this term in the activities. When you need
to write the key term or its definition, highlight the term or the definition.
BUILD Understanding
T-Chart A T-chart is a way to organize information. One type of T-chart organizes main
ideas and details. List the main ideas on the left side of the chart. On the right side, write
details and examples that support those ideas.
As you read Lesson 2, complete the T-chart. Write the green headings from your text in
the left column. These are the main ideas. List details and examples that support each main
idea in the right column. One has been done for you.
Main Idea
The Components of DNA
Details and Examples
DNA is an example of a nucelic acid and is made up of smaller units called
nucleotides.
Solving the Structure
Sample answer: Scientists who contributed to solving the struc-
of DNA
ture of DNA were Chargaff, Franklin, and Watson and Crick.
The Double-Helix
Sample answer: DNA runs in antiparallel strands. The helix is held
model
together by hydrogen bonds and is organized into base pairs.
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Solving the Structure of DNA
Three scientists who worked to solve the structure of DNA were Rosalind Franklin, James
Watson, and Francis Crick. Franklin found clues. These clues helped Watson and Crick
explain the structure and properties of DNA.
A Venn diagram is made up of overlapping circles. It is a useful tool for comparing two
or even three topics. In the space where the circles overlap, write the features that the topics
share. In the space where the circles do not overlap, write the features that are unique to
each topic.
Complete the Venn diagram using phrases from the word box.
built a three-dimensional model of DNA
helped determine the shape of a DNA molecule
photographed DNA using X-ray diffraction
showed that DNA is a double helix
studied DNA’s structure and properties
Work of
Franklin
• photographed
DNA using X-ray
diffraction
Work of
Watson and Crick
Both
• studied DNA's
structure and
properties
• helped determine
the shape of a
DNA molecule
• showed that DNA is
a double helix
• built a threedimensional model
of DNA
Answer the questions. Circle the correct answer.
1. Who first photographed DNA using X-ray diffraction?
Franklin
Watson and Crick
2. Who first built a three-dimensional model of DNA?
Franklin
Watson and Crick
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Solving the Structure of DNA
Nucleic Acid and Nucleotides DNA is made of long chains of nucleotides. Each
nucleotide contains three basic parts: a base, a deoxyribose molecule, and a phosphate group.
There are four different bases: adenine, cytosine, guanine, and thymine. Only one base is
found in each nucleotide.
Follow the directions.
1. In the diagram below, the sequence of nucleotides has the code AGCT. Color the diagram
using this key:
deoxyribose: red
phosphate group: blue
adenine: yellow
cytosine: green
guanine: orange
thymine: black
2. Circle one complete nucleotide.
(blue)
(red)
(yellow)
(orange)
(green)
(black)
Answer the questions.
3. Circle the correct answers. What two parts do all nucleotides have in common?
guanine
deoxyribose
phosphate group
4. Each nucleotide is connected to the next nucleotide. The connection is found between
A. sugar of one nucleotide and phosphate of another
B. base of one nucleotide and sugar of another
C. phosphate groups of two nucleotides
5. What are the parts of a DNA nucleotide? deoxyribose, phosphate group, base
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The Double-Helix Model
Base Pairings Four nucleotides make up DNA: adenine, cytosine, guanine, and thymine.
These nucleotides always occur in pairs called base pairs. The diagram below is a model
of DNA.
Follow the directions.
1. Write the missing letter to complete each base pair. The first two have been done for you.
Key
A = Adenine
C = Cytosine
G = Guanine
T = Thymine
C
G
A
T
G
C
G
C
C
G
C
G
T
A
A
T
C
G
Answer the questions.
2. What nucleotide is always paired with thymine?
adenine
3. What nucleotide is always paired with guanine?
cytosine
4. Whose rule does base pairing prove?
Chargaff’s
5. Suppose a strand of DNA has the following code on one side.
AGT CCA GTA
What would be the matching other side of a DNA strand?
TCAGGTCAT
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12.3 DNA Replication
Lesson Objectives
Summarize the events of DNA replication.
Compare DNA replication in prokaryotes with that of eukaryotes.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
DNA
polymerase
Enzyme that joins individual
nucleotides to make a strand
of DNA
Poly- means “many” and DNA polymerase
joins many nucleotides.
Replication
The process of duplicating DNA
DNA makes a replica during replication.
Telomere
The tip of a chromosome
Both telomere and tip begin with T, so I
can remember that a telomere is the tip of
a chromosome.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
BUILD Understanding
Preview Visuals Previewing visuals and taking notes about them can help you remember
what you read and review for tests. Look at the diagram of DNA Replication in your textbook.
Write down any questions you may have about it. Then, as you read Lesson 3, find the answers
to your questions. Organize your questions and answers in the two-column table below.
Questions
• What causes the DNA to split?
Sample questions:
• What is DNA polymerase?
• Is each new strand of DNA identical?
Answers
• Enzymes break the hydrogen bonds.
Sample answers:
• It is the enzyme that joins individual
nucleotides to produce a new strand
of DNA.
• Each strand is a near-perfect copy of the
original DNA.
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Copying the Code
The Role of Enzymes Enzymes have several important jobs in DNA replication. The jobs
of some enzymes are listed below.
Write the jobs in the order in which they occur.
join free nucleotides to existing DNA strand
unzip DNA
unwind DNA
1.
unzip DNA
2.
unwind DNA
3.
join free nucleotides to existing DNA strand
The diagram below shows the replication of DNA. Look carefully at the diagram.
Nitrogenous
bases
Original
strand
Replication fork
DNA polymerase
New strand
Direction of
Replication
Direction of
Replication
New strand
DNA
polymerase
Original
strand
Replication
fork
Answer the questions.
4. In your own words, define the word replicate. Sample answer: To replicate is to make a
copy.
5. Enzymes usually end in -ase. What is the name of the enzyme that joins individual
DNA polymerase
nucleotides?
6. Circle the correct answer to complete the sentence. A(n)
where a DNA strand opens to make new strands.
original strand
old strand
is the place
replication fork
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Replication in Living Cells
During replication, a DNA molecule copies itself. In eukaryotes, DNA is organized into
chromosomes within the nucleus. In prokaryotes, DNA is a circular molecule that is free in
the cytoplasm.
Follow the directions.
1. Label one diagram as Prokarytic DNA.
2. Label the other as Eukaryotic DNA.
3. Label both drawings with the following terms: unreplicated DNA, replication fork, origin
of replication.
Replication
fork
Origin of
replication
Replication
fork
Unreplicated
DNA
Prokaryotic DNA
Unreplicated
DNA
Replication
forks
Origins of
replication
Eukaryotic DNA
Answer the questions. Circle the correct answers.
4. In which type of cell is DNA circular?
prokaryotic
eukaryotic
5. In which type of cell does replication begin at several points?
prokaryotic
eukaryotic
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Inquiry Into Scientific Thinking
Modeling DNA Replication Before a cell divides, it duplicates its DNA. This copying
process is known as replication. Replication ensures that each cell has the same complete set
of DNA molecules. Use your textbook to complete the flowchart on DNA replication. Use the
phrases in the box below.
Replication forks form.
New bases are added to each strand.
Original DNA molecule
Produces two strands of DNA identical to the original strand
Original DNA
molecule
New bases are
added to each
strand.
Enzymes unzip
DNA strand.
Produces two
strands of DNA
almost identical
to the original
strand
Replication
forks form.
Analyze and Conclude
1. If you did the Quick Lab in the textbook, list the base pairs in the strand of DNA made by
your partner. Sample answer: ATCGGATCA
2. List the base pairs in the complementary strand of DNA that you made. Sample answer:
TAGCCTAGT
3. In your own words, write a definition of DNA replication. Sample answer: During
replication, one strand of DNA duplicates to make two identical strands.
4. What is the importance of replication? Why do cells replicate their DNA before dividing?
to maintain genetic information before dividing, or so that new cells have the correct
genetic information
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Chapter Review
Use the clues and words to help you write the vocabulary terms from the chapter in the
blanks. You may use a word once or not at all.
bacteriophage
base pairing
DNA polymerase
replication
telomere
telomere
1. tip of a chromosome
2. enzyme that joins nucleotides to make a new strand of DNA DNA polymerase
bacteriophage
3. virus that infects bacteria
replication
4. process of making a copy of DNA
Answer the following questions. Use the diagram to answer Questions 5 and 6.
A
5. What is the structure shown above?
A. replication fork
C. enzyme
B. nucleotide
D. hydrogen bond
6. What is the molecule labeled A?
A. sugar
C. nitrogen base
B. phosphate group
D. deoxyribose
7. Use the terms below to draw a linear graphic organizer in the space below.
adenine
bases
cytosine
DNA
guanine
thymine
Adenine
Cytosine
DNA
Bases
Nucleotides
Guanine
Thymine
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Taking a Standardized Test
Test Taking Tip: Questions with the Word Not
When a question includes the word not, cross out answer choices you know are true of the
question. Choose your answer from the remaining choices.
Read the following questions and answer choices.
DNA contains four nitrogen bases. Which of the following is not a base in DNA?
A. cytosine
B. guanine
C. deoxyribose
D. thymine
Step 1 What is the question asking? In this question, you need to determine which answer
choice is not a base found in DNA.
Step 2 Read each answer choice carefully.
Step 3 Eliminate answers that you know are DNA bases. For example, you may remember
that cytosine and guanine are two bases that make up DNA. You can cross out these two
answers.
Step 4 Choose one of the answers left. You have two answers left: C, deoxyribose, and D,
thymine. You know that deoxyribose is a sugar and not a base. Therefore, the correct answer
is C, deoxyribose.
Self-Test
Practice what you have learned by answering the following questions. Remember, you need
to find the answer that is not true. Circle that answer.
1. Which scientist did not help determine the structure of DNA?
A. James Watson
B. Frederick Griffith
C. Francis Crick
D. Rosalind Franklin
2. Which of the following is not a job of DNA?
A. storing genetic information
B. copying genetic information
C. transmitting genetic information
D. mutating genetic information
3. Which is not true of a DNA molecule?
A. The backbone is made of sugars and phosphates.
B. The molecule is made of two strands.
C. Sugars are paired in the center of the molecule.
D. The molecule is shaped like a double helix.
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4. Which statement is not true about DNA replication?
A. Prokaryotes replicate their DNA.
B. Eukaryotes replicate their DNA.
C. Cytosine is an enzyme that helps in replication.
D. DNA replication occurs before a cell divides.
5. Which statement is not true of bacteriophages?
A. They inject proteins into cells.
B. They are viruses.
C. They infect bacteria.
D. They inject their DNA into cells.
6. What statement does not describe DNA in a eukaryotic cell?
A. DNA is contained in chromosomes.
B. Enzymes are needed to replicate DNA.
C. DNA must be unzipped before replication starts.
D. DNA is not enclosed in a nucleus.
7. Which strands of bases are not correctly paired?
A. TATCCC
ATAGGG
B. CCGATT
GGCTAA
C. CATTAG
TCAATA
D. ACTCCC
TGAGGG
8. Which is not part of a DNA nucleotide?
A. phosphate group
B. sugar
C. protein
D. nitrogen base
Short-Response Question
Answer the following question in two or three sentences.
9. How is DNA is like a computer program?
Sample answer: DNA is like a computer program because it contains the information
that determines genes and helps living things carry out certain tasks. In the same
way, the information in a computer program makes it possible for the computer to
function and carry out certain tasks.
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RNA and Protein Synthesis
Information and Heredity
Q: How does information flow from DNA to RNA to direct the synthesis
of proteins?
Chapter Summary
The diagram below shows what you will read about in this chapter and how the chapter is
organized. Study the diagram. Then answer the questions that follow.
13.1 RNA
The role of RNA
RNA synthesis
The genetic code
13.2 Ribosomes
and Protein
Synthesis
Translation
The molecular basis of heredity
13.3 Mutations
Types of mutations
Effects of mutations
Prokaryotic gene regulation
13.4 Gene
Regulation and
Expression
Eukaryotic gene regulation
Genetic control of development
1. What are the four main topics in this chapter? RNA, ribosomes and protein synthesis,
mutations, gene regulation and expression
2. What process do you expect to learn about in Lesson 1?
How RNA is made
3. Name two things you expect to learn about mutations in Lesson 3. Types and effects of
mutations
4. In Lesson 4, what are two types of gene regulation?
prokaryotic and eukaryotic
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13.1 RNA
Lesson Objectives
Contrast RNA and DNA.
Explain the process of transcription.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term.
Term
Definition
How I’m Going to Remember
the Meaning
Exon
Coding region of a gene that is
expressed; exons are kept and put
together to form mRNA
If a puzzle piece is an exact fit, you
keep it in place. Exons are pieces that
are kept.
Intron
Noncoding sequence of a gene that
is cut out and discarded
Messenger
RNA
mRNA; RNA molecules that carry
instructions for assembling proteins
Messenger RNA carries the message of how
to make proteins.
Ribosomal
RNA
rRNA; RNA molecules that make up
ribosomes, on which proteins are
assembled
Ribosomal RNA makes up ribosomes.
RNA
Ribonucleic acid; nucleic acid that
helps put the genetic code in DNA
into action
RNA molecules are the carriers of
the code for proteins.
RNA
polymerase
An enzyme that separates DNA
strands and uses one strand to
make RNA
RNA is a polymer. RNA polymerase is
the enzyme that builds the polymer.
Transcription
Process in which RNA molecules
are made using DNA as a template
Transfer RNA
tRNA; RNA molecule that transfers
amino acids to the ribosomes
An intron is the part of RNA that is
in between exons.
Transcribe means writing down what
someone says. In transcription, RNA
molecules are written from DNA.
Transfer RNA transfers amino acids.
Note: Students should highlight terms and definitions used throughout the chapter.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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BUILD Understanding
Preview Visuals Previewing the visuals in a lesson can give you an idea about what you
will learn. Visuals include photographs, charts, graphs, and diagrams.
Before you read the lesson, preview the Transcribing DNA into RNA diagram. Then
use the chart below to predict how you think a cell makes RNA. As you read the lesson, add
notes to your chart about how RNA is made. After you read, compare your prediction to
your notes.
Prediction
Students’ predictions should explain how
they think a cell makes RNA.
Notes
Students’ notes should explain how a cell
makes RNA.
How my notes compare to my prediction:
BUILD Connections
Master Plans and Blueprints An analogy takes two things that seem to be different and
shows how they can be similar. In this visual analogy, DNA is compared with a master plan,
and RNA is compared with blueprints.
Answer the questions. Use the terms DNA, RNA, and nucleus in your answers.
1. The master plan stays in the office. Why is DNA like the master plan? DNA stays in the
nucleus.
2. Blueprints go out of the office to the building site. Why is RNA like a set of blueprints?
RNA goes outside the nucleus to the building site.
3. Find a partner. Using the analogy, explain the different functions of RNA and DNA to
your partner.
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RNA Synthesis
In transcription, RNA polymerase separates the two DNA strands. RNA then uses one strand
as a template to make a complementary strand of RNA. RNA contains the nucleotide uracil
instead of the nucleotide thymine.
Follow the directions.
1. Label the RNA
2. Label the DNA.
3. Use the key to label the missing nucleotides marked on the diagram.
RNA
G
U
C
C
A
A
G
T
RNA polymerase
Key
DNA
RNA
A = Adenine A = Adenine
C = Cytosine C = Cytosine
G = Guanine G = Guanine
T = Thymine U = Uracil
DNA
Answer the questions. Circle the correct answer.
4. In DNA,
adenine
5. In RNA,
uracil
6. In DNA,
uracil
is always paired with cytosine.
guanine
uracil
replaces thymine.
cytosine
adenine
is paired with adenine.
thymine
guanine
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RNA Synthesis
In DNA replication a cell copies its DNA. Both strands of the double helix are used as
templates to make complementary, or matching, strands of DNA. In DNA transcription a
single strand of DNA is used as a template to generate a strand of mRNA.
Follow the directions.
1. Fill in the missing information. One row has been completed for you.
Template
Complementary DNA
Messenger RNA (mRNA)
TTACGG
AATGCC
AAUGCC
CCGCCG
GGCGGC
GGCGGC
TGCATC
ACGTAG
ACGUAG
AGACTC
TCTGAG
UCUGAG
CTATTC
GATAAG
GAUAAG
GACCGATGT
CTGGCTACA
CUGGCUACA
Answer the questions.
2. What is the mRNA if the complementary DNA is TCTGAG?
3. What does a cell copy in DNA replication?
AGACUC
DNA
4. How many strands of DNA are used to make complementary strands of DNA?
1
5. How does the cell make RNA? During transcription, a single strand of DNA is used as a
template to generate a strand of mRNA.
6. What are introns? segments of RNA that are cut out before the formation of the final
mRNA molecule
7. What are exons? the segments of RNA that are left after the introns are removed
Follow the directions.
Create your own example of DNA. Fill in the chart.
Template
Possible response:
GAACGAATG
Complementary DNA
Possible response:
CTTGCTTAC
Messenger RNA (mRNA)
Possible response:
CUUGCUUAC
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13.2 Ribosomes and Protein Synthesis
Lesson Objectives
Identify the genetic code and explain how it is read.
Summarize the process of translation.
Describe the “central dogma” of molecular biology.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Anticodon
Group of three nucleotide bases
in tRNA that is complementary
to one codon
Anti- means “against or opposite.” The
anticodon is the opposite of the codon.
Codon
Group of three nucleotide
bases in mRNA that specifies
an amino acid
A codon codes for one amino acid.
Gene
expression
The way genetic information is
put into action
Genetic code
Language made up of letters
that stand for the nucleotide
bases in RNA and DNA
Polypeptide
Long chains of amino acids that
make up proteins
Translation
Process of decoding mRNA in
order to make a protein
Gene expression is the way genetic information is expressed, or put into action.
In a code, letters can stand for other letters.
Letters in the genetic code stand for nucleotides.
Poly- means “many.” Polypeptide is a
chain of many amino acids.
Translate means “decode.” Translation
here is decoding mRNA.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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BUILD Understanding
Two-Column Table A two-column table is a way to take notes about what you have read.
Complete the table with the main idea of each section. The first one has been done for you.
Section Heading
Main Idea
The Genetic Code
The genetic code is read three “letters” at
a time. Each “word” is three bases long and
corresponds to a single amino acid.
Translation
Ribosomes use the sequence of codons in
mRNA to assemble amino acids into polypeptide chains.
The Molecular Basis of Heredity
Information is transferred from DNA to
RNA to protein.
The Genetic Code
A codon is a group of three nucleotide bases in messenger RNA. Each codon corresponds to
one amino acid.
Follow the directions.
1. Circle each codon in the diagram of RNA below.
A
U
G
U
C
G
A
A
C
Answer the questions. Circle the letter of the correct answer.
2. What is a polypeptide?
A. a chain of amino acids
B. a chain of enzymes
3. What does the letter A stand for in the genetic code?
A. amino acid
B. adenine
4. Can a codon contain two of the same nucleotide bases?
A. yes
B. no
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The Genetic Code
The diagram below shows the mRNA codes that correspond to amino acids and stop codons.
Read the diagram from the center outwards. For example, the mRNA code UAC corresponds
to the amino acid tyrosine.
Follow the directions.
C
U
G
A
in
Ser
hion
ine
e
Met
e
ne
ine
e
nin
lin
tam
reo
Pro
G
di
GA
UG
AC U G A C U
Arginin
Th
U G
U
C
sti
As
C
A
Glu
pa
A AGU Cysteine
C
G AG TryStoptop phan
U
U AC Leucine
G
C ACU
G U
A C
C
e
in
os
r
Ty
U
p
C
Sto
Hi
g
ra
GA
A G U C
ine
G
A
C
U
G
Valine A
C
U
G
Arginine A
C
e U
n
i
r
e
S
G
e A
n
i
C
Lys
eU
G UC A G
UC A
UC
AG
A
C
G
U
Isoleuc
e
e
nin
ine
Glycin
ic
tam
Glu cid ic
a
rt
pa d
As aci
Ala
Phenylalanine
Leu
cine
1. In the chart below the diagram, write the name of the amino acid that corresponds to each
mRNA code.
mRNA Code
Amino Acid
AAA
lysine
GCG
alanine
GAU
aspartic acid
CAA
glutamine
Answer the questions.
2. Which two mRNA codes correspond to histidine?
CAU & CAC
CAA & CUC
3. How many different mRNA codes correspond to arginine?
2
4
6
4. How many different mRNA codes correspond to methionine?
1
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Translation
During translation, transfer RNA (tRNA) anticodons match to messenger RNA (mRNA)
codons. Each tRNA molecule can carry one particular amino acid. The amino acids are joined
to form a polypeptide.
Follow the directions.
1. Number the four tRNA anticodons in the order in which they should appear to match the
codons in the mRNA strand.
A U G U U C A A A C U G
mRNA
phenylalanine
leucine
lysine
methionine
A A G
G A C
U U U
U A C
2
4
3
1
Answer the questions.
2. Which anticodon matches the mRNA codon UUC?
AAG
3. Which amino acid is carried by the anticodon UUU?
lysine
4. List the amino acids in the order they would appear in the polypeptide coded for by the
mRNA.
methionine, phenylalanine, lysine, leucine
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13.3 Mutations
Lesson Objectives
Define mutations and describe the different types of mutations.
Describe the effects mutations can have on genes.
BUILD Vocabulary
A. The chart below shows the key terms in this lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Frameshift
mutation
Point mutation that inserts or
deletes nucleotide bases
Mutagen
Chemical or physical things in
the environment that can cause
mutations
A mutagen can cause a mutation.
Mutation
Change in genetic information
that can be inherited
In movies, a mutant is different, or
changed, from other humans.
Point
mutation
Mutation that changes one or a
few nucleotides
A point is a small dot. A point mutation
is a small change.
Polyploidy
Condition in which an organism
has extra sets of chromosomes
Poly- means “many.” Polyploidy is when
an organism has too many chromosomes.
Shift means “move.” When you insert or
delete a base, the other bases shift to fill
in the gap.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
BUILD Understanding
Preview Visuals Before you read the lesson, look at the two diagrams of point mutations
and chromosomal mutations. Use the information in the diagram of point mutations to
complete the concept map below.
Point Mutations
Substitution
Deletion
Insertion
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Types of Mutations
Gene mutations produce a change in one gene. Point mutations produce gene mutations that
involve a change in one or more nucleotides. Point mutations also occur at only one point in
the DNA sequence. The diagram below shows an original chromosome and three possible
point mutations.
Follow the directions.
1. Use the words in the box to add headings to the three lower parts of the diagram.
insertion
deletion
substitution
Before Mutations (normal)
T AC G C A T GGA A A
AUGC GUA C C U U U
Met
deletion
Arg
Thr
Phe
insertion
substitution
G
T A C C A T G G A A T ..
A U G G U A C C U U A ..
Met
Val
T
C
Pro
?
T AC AG C A T G G A A A
AUG U C G UA C C U U U
Met
Ser
Tyr
Leu
TAC GT A T GG AAA
AUG CA U A C C U U U
Met
His
Thr
Phe
Complete the sentences. Use the terms from the box above.
2. In a(n)
substitution
3. In a(n)
insertion
, a base is inserted into the DNA sequence.
4. In a(n)
deletion
, one base is removed from the DNA sequence.
, one base is changed to a different base.
Answer the questions.
5. Which of the following can result in a frameshift mutation? Circle each correct answer.
A. deletion
B. substitution
C. insertion
6. Why is a frameshift mutation more damaging than a substitution? A frameshift mutation
causes all of the codons after the mutation to be “read” differently by the ribosome.
So frameshift mutations can affect many genes. A substitution only affects one codon.
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Types of Mutations
Mutations that change whole chromosomes are called chromosomal mutations. The diagrams
below show chromosomal mutations. Each diagram represents an original chromosome and
a possible mutation of the chromosome.
Original Chromosome
AB C
Deletion
DE F
AC
Inversion
Original Chromosome
AB C
DE F
AED
Original Chromosome
AB C
DE F
DE F
CBF
Translocation
ABC
Original Chromosome
AB C
DE F
J KL DE F
Duplication
ABBC
DE F
Follow the directions.
1. Use the diagrams to help you complete the table.
Mutation
Description
deletion
Part of the chromosome is lost.
duplication
Extra copies of a part of a chromosome are made.
translocation
Part of a chromosome breaks off and attaches to
another chromosome.
inversion
Sections of a chromosome are reversed.
Answer the questions.
2. Which types of mutations can add genes to a chromosome? duplication and translocation
3. Which type of mutation can take genes away from a chromosome?
deletion
4. Which type of mutation changes the order of the genes, but not the number of genes in a
inversion
chromosome?
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13.4 Gene Regulation and Expression
Lesson Objectives
Describe gene regulation in prokaryotes.
Explains how most eukaryotic genes are regulated.
Relate gene regulation to development of multicellular organisms.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term.
Term
Definition
How I’m Going to Remember
the Meaning
Homeotic
gene
Master control gene that
regulates how cells develop into
specific parts of the body
Homeotic genes control the development
of different organs.
Operon
Group of genes that are
regulated together
An operon is a group of genes that operate
together.
Operator
Region where the lac repressor
can bind to DNA
When the lac repressor binds to the
operator, it turns off.
RNA
interference
Blocking gene expression with
small RNA molecules
Interfere means “block.” RNA
interference blocks gene expression.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
BUILD Understanding
Concept Map Complete the concept map by filling in the main ideas of Lesson 4. Use the
following terms: transcription factors, DNA-binding proteins, master control genes.
Prokaryotic Gene
Regulation
involves
DNA-binding proteins
Eukaryotic Gene
Regulation
often involves
Transcription factors
involves
Master control genes
Genetic Control of
Development
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Prokaryotic Gene Regulation
DNA-binding proteins called repressors control transcription. They bind to areas of DNA
called operators. They stop RNA polymerase from transcribing the genes on the DNA strand.
Answer the following questions. For each question, circle the letter of the correct answer.
1. What is the function of the lac operon in E. coli ?
A. It regulates reproduction.
B. It regulates cell division.
C. It enables the bacterium to use lactose for food.
D. It uses three proteins to make lactose.
2. What does the lac repressor do?
A. It prevents the lac operon from working by preventing transcription.
B. It makes RNA polymerase, which prevents the lac operon from working.
C. It makes lactose.
D. It makes glucose.
3. What happens when lactose is E. coli’s only food source ?
A. The presence of lactose keeps RNA polymerase from functioning.
B. The presence of lactose enables the lac operon genes to function.
C. The presence of lactose allows DNA to be synthesized.
D. The presence of lactose makes the lac repressor go into action.
4. What does the promoter do?
A. It prevents the synthesis of lactose.
B. It is the place where RNA polymerase can bind to DNA and therefore start the
synthesis of mRNA.
C. It is the place where RNA polymerase can bind to DNA and enable the lac repressor
gene to work.
D. It lets the lac repressor bind to DNA.
In the space below, draw what happens to the repressor when lactose is present.
Students’ drawings should resemble the
illustration in the textbook.
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Eukaryotic Gene Regulation
In many eukaryotes, a short region of DNA containing the base sequence TATATA or
TATAAA is known as the TATA box. The TATA box marks the beginning of a gene. It also
helps position the RNA polymerase. When RNA polymerase binds in the correct position,
transcription can occur.
Follow the directions.
1. Label the TATA box, the gene, and the RNA polymerase in the diagram below.
RNA polymerase
Direction of
transcription
TATA Box
Gene
Complete the sentences.
2. The TATA box helps
RNA polymerase
3. The TATA box marks the beginning of the
bind in the correct place.
gene
.
CHAPTER
Mouse-Eyed Fly The chapter mystery involves an experiment in which scientists
transplanted a mouse gene into a fruit fly. The mouse gene is involved in the formation
of eyes. The fruit fly then grew eyes in odd places, such as its legs.
Imagine you are writing a Web article about this experiment. To learn more about
the experiment, you will interview one of the scientists. In the space below, write some
questions that you might ask the scientist. One question has been done for you.
• When you planned the experiment, what was your hypothesis?
Sample questions: Why did you choose a mouse gene to transplant, instead of the
gene of another insect? Were the eyes that developed more like mouse eyes, or
more like normal fruit-fly eyes? How did you insert the mouse gene into the fruit
fly’s genome?
Encourage students to try to find answers to the questions they write. You might
find a geneticist to talk to the class about the experiment.
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Inquiry Into Scientific Thinking
The Discovery of RNA Interference Since the discovery of RNA interference, scientists
have been investigating the use of RNA interference to treat disease. Rearchers have found
that “silencing” a gene—preventing it from expressing—is a relatively simple process in
the laboratory.
Use the following terms to complete the chart below: hepatitis, AIDS, cancer
Disease
AIDS
hepatitis
cancer
Possible RNA Interference
Treatments
• block genes in HIV that cause replication
• target human gene that is the receptor for HIV
• block genes that help produce a protein
associated with liver damage
• silence genes associated with uncontrolled cell
growth
Analyze and Conclude
Answer the questions.
1. What do RNA interference treatments for AIDS, hepatitis, and cancer have in common?
They all block certain genes from being expressed.
2. Why do you think it might be important to have more than one treatment for a virus that
adapts quickly, such as HIV?
An adaptable virus may adapt to one treatment, so it is important to have many
possible treatments.
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Chapter Review
Use the clues and words to help you write the vocabulary terms from the chapter in the
blanks. You may use a word once, more than once, or not at all.
codon
anticodon
mutation
promoter
1. a change in genetic material
mutation
2. region of DNA where RNA polymerase can bind
promoter
codon
3. group of three nucleotide bases in mRNA
Answer the questions.
4. What causes cell differentiation during an organism’s development? Special master
control genes tell the body’s cells how to differentiate as the organism grows.
5. Which of the following is a type of point mutation?
A. duplication
C. insertion
B. inversion
D. translocation
6. Use these phrases to complete the Venn diagram: requires RNA polymerase; part of gene
expression; proteins are made; RNA is made; protein synthesis.
Transcription
Translation
Both
requires RNA polymerase
part
of gene
RNA is made.
expression
protein synthesis
Proteins are made.
7. Complete the sentence about the diagram below.
G H
A B C
D E
F
A B G H C
D E
F
In the diagram, one part of the chromosome breaks off and
This is called
translocation
attaches
to another.
.
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Taking a Standardized Test
Test-Taking Tip: Work the Math Problems
When a question has a math problem, work the problem on scrap paper before looking at the
answers.
Read the following question and answer choices.
A strand of mRNA contains 18 nucleotide bases. How many amino acids are in the
polypeptide assembled from this mRNA?
A. 18
B. 9
C. 6
D. 3
Step 1 Read the question carefully. Make sure you understand what the question is asking.
This question is asking you to figure out how many amino acids are in a polypeptide.
Step 2 Work out the answer to the question on scrap paper. You know that there are three
nucleotide bases for each amino acid. 18 ÷ 3 = 6.
Step 3 Compare your answer with the answer choices. If you find that none of the answer
choices matches your answer, go back and look for mistakes in your calculations.
Step 4 Choose the answer choice that matches your answer. Since your answer was 6, you
would choose answer choice C.
Self-Test
Practice what you have learned by answering the following questions. For each question, first
work the problem on scrap paper. Then compare your answers to the choices and circle the
correct answer.
1. A polypeptide is made up of 23 amino acids. How many nucleotide bases are there in the
mRNA?
A. 72
B. 69
C. 46
D. 13
2. How many codons are there in a chain of 12 nucleotides?
A. 3
B. 4
C. 6
D. 12
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3. How many nucleotide bases are there in 24 codons?
A. 24
B. 36
C. 48
D. 72
4. A strand of mRNA that is 72 nucleotide bases long would need how many molecules of
tRNA to carry amino acids?
A. 72
B. 48
C. 24
D. 12
5. A strand of mRNA contains 27 nucleotide bases. How many amino acids are in the
polypeptide assembled from this mRNA?
A. 27
B. 18
C. 9
D. 3
Short-Response Question
Answer the following question in two or three sentences.
6. Suppose someone told you that mutations to DNA are always harmful. Do you agree with
this statement? Why or why not?
Sample answer: This is an inaccurate statement. Many mutations don’t change the
protein that DNA encodes, so they don’t have any effect on an organism’s traits.
Some mutations may be beneficial to help an organism survive.
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Human Heredity
Information and Heredity
Q: How can we use genetics to study human inheritance?
Chapter Summary
The diagram below shows what you will read about in this chapter and how the chapter is
organized. Study the diagram. Then answer the questions that follow.
Karyotypes
14.1 Human
Chromosomes
Transmission of human traits
Human pedigrees
14.2 Human Genetic
Disorders
From molecule to phenotype
Chromosomal disorders
14.3 Studying
Manipulating DNA
the Human
Genome
The Human Genome Project
1. What are the three major topics in Lesson 1? karyotypes, transmission of human traits,
human pedigrees
2. What do you think a chromosomal disorder is? a human genetic disorder involving
chromosomes
3. In Lesson 3, what does the word manipulating mean? Students may infer that
manipulating means changing or reworking.
4. Can you predict what the Human Genome Project is about? Students’ answers should
include that it is a project researching something about humans. Some students may
also include that it is researching human genes.
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14.1 Human Chromosomes
Lesson Objectives
Identify the types of human chromosomes in a karyotype.
Describe the patterns of inheritance of human traits.
Explain how pedigrees are used to study human traits.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the chart
by writing a strategy to help you remember the meaning of each term. One has been done
for you.
Term
Definition
How I’m Going to Remember
the Meaning
Autosome
The 44 human chromosomes
that are not sex chromosomes
Auto- means “self.” Autosomes determine human
traits other than sex.
Genome
The full set of genetic
information that an organism
carries in its DNA
Genome is all of the genetic information.
Karyotype
A picture that shows
chromosomes grouped together
in pairs
Karyotypes carry a picture of
chromosomes.
Pedigree
A chart that shows the
relationships in a family
Compare to a dog’s pedigree
Sex
chromosomes
The chromosomes that
determine if an individual is a
male or female
Sex chromosomes are the chromosomes
that determine the sex of a person.
Sex-linked
gene
A gene located on a sex
chromosome
Link means “connected.” Sex-linked genes
are connected to the sex chromosomes.
B. As you work through this lesson, you may find these terms in the activities. When you
write a key term or a definition, highlight the term or the definition.
Note: Students should highlight terms and definitions used throughout the chapter.
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BUILD Understanding
Spider Map A spider map organizes the topic's main ideas and details. As you read the
lesson, look for the main ideas. Within each idea, look for details. Add details to the spider
map. Some have been added for you.
HUMAN
CHROMOSOMES
KARYOTYPES
sex chromosomes
autosomal
chromosomes
HUMAN
PEDIGREES
dominant and
recessive alleles
TRANSMISSION
OF
HUMAN TRAITS
Mendel’s Principles
of Genetics
Shows traits according to
relationship between parents
codominant and
multiple alleles
sex-linked inheritance
pedigree diagram
x-chromosome
inactivation
Transmission of Human Traits
Codominant and Multiple Alleles The ABO blood group gene codes for different
antigens on the surface of a person’s red blood cells. There are three alleles for this gene: IA, IB,
and i. Depending on a person’s alleles, they can have A antigens, B antigens, both, or none.
Label the antigens on the red blood cells. Use these labels: B only, A only, both, or none. The
first one has been done for you.
Blood Groups
Blood Type
Genotype
Antigen on
Red Blood Cell
A
I AI A or I Ai
A only
B
I BI B or I Bi
B only
AB
AB
I I
both A and B
O
ii
none
Answer the questions.
IA and IB
1. Which blood-group alleles are codominant?
2. Which allele is recessive?
i
3. A patient gives a blood sample in which the red blood cells have A antigens. What are three
possible genotypes for that blood sample?
IAIA, IAi, or IAIB
4. The blood type O can be safely given in a transfusion to all blood types. Why? There are
no A or B antigens on a type O red blood cell.
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Inquiry Into Scientific Thinking
How Is Colorblindness Transmitted? Look at the Quick Lab in the textbook. In the
model using the red and white beans, “Mother” was not colorblind, but she was a carrier for
colorblindness. “Father” was colorblind.
Complete the Punnett square below, which reflects your model. Xb indicates the allele
for colorblindness.
Xb
Y
Xb
XbXb
XbY
X
XbX
XY
Analyze and Conclude
1. According to the Punnett square for your model, is it possible for this mother and father
yes
to have a boy who is not colorblind?
2. According to the Punnett square for your model, is it possible for this mother and father
to have a girl who does not have the colorblind allele?
no
3. Which of the following is true of this mother and father?
A. They could have either a colorblind girl or a colorblind boy.
B. They could have a colorblind girl, but not a colorblind boy.
CHAPTER
The Crooked Cell Ava searched the Internet for information about sickle cell disease.
She learned a lot about this genetic disorder.
Do research about sickle-cell disease, then design a web page that provides information
for people like Ava.
Web pages should have information about
the inheritance of sickle-cell disease and the
effects of the disease.
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Human Pedigrees
A pedigree chart is a diagram that shows family relationships. This pedigree chart shows how
the trait of a white lock of hair has been inherited in a family. The allele that codes for a white
lock of hair is dominant.
A White Lock of Hair
A circle represents
a female.
A square represents
a male.
A vertical line
and a bracket
connect the
parents to their
children.
A horizontal line connecting
a male and female represents
a marriage.
Ww
ww
A circle or square that is
not shaded indicates
that a person does not
express the trait.
A shaded circle or square
indicates that a person
expresses the trait.
Answer the questions.
1. How many generations are shown in this pedigree?
2. How many males in the chart have a white lock of hair?
three
three
3. What symbol represents a female with at least one allele for a white lock of hair?
a black circle
4. The genotypes of two of the people in the chart are provided. What are the alleles of their
three children?
Son without white lock:
Son with white lock:
Daughter with white lock:
ww
Ww
Ww
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14.2 Human Genetic Disorders
Lesson Objectives
Explain how small changes in DNA cause genetic disorders.
Summarize the problems caused by nondisjunction.
BUILD Vocabulary
A. The chart below shows a key term in this lesson with its definition. Complete the chart by
writing a strategy to help you remember the meaning of the term.
Term
Definition
How I’m Going to Remember
the Meaning
Nondisjunction
An error in meiosis in which
homologous chromosomes fail
to separate
The prefixes non- and dis- mean “not”
and junction means “together.” Nondisjunction means the chromosomes are
together.
B. As you work through this lesson, you may find this term in the activities. When you write
the key term or its definition, highlight the term or the definition.
BUILD Understanding
Two-Column Chart A two-column chart is a way to take notes about what you read.
Preview the text by looking at the headings and visuals. Write four questions you have about
genetic disorders in the left column. As you read, write the answers to your questions in the
right column. The first one has been done for you.
Sample questions and answers:
Questions I Have
Answers I’ve Found
1. What are some disorders caused by genes?
1. sickle cell disease, cystic fibrosis, and
Huntington’s disease
2. What causes cystic fibrosis?
2. the loss of a single amino acid,
phenylalanine
3. What are the symptoms of Huntington’s
3. mental deterioration and uncontrollable
movements
disease?
4. What is nondisjunction?
4. the failure of homologous chromosomes
to separate during meiosis
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From Molecule to Phenotype
Disorders Caused by Individual Genes Though it may seem unlikely, there are some
advantages to the genes that cause sickle cell disease and cystic fibrosis. The alleles that
cause these diseases can be fatal for people who carry them. However, they also can provide
protection from other diseases.
Sickle Cell Allele
Cystic Fibrosis Allele
Individuals with just one copy of the sickle
cell allele are resistant to the parasite that
causes malaria.
The protein produced by the cystic fibrosis
allele prevents the bacterium that causes
typhoid from entering the body through the
digestive system.
African people with only one sickle cell allele
survive malaria outbreak.
Europeans with a single CF allele survive
typhoid outbreak during medieval times.
They are more likely to reproduce and pass
the allele on.
They are more likely to reproduce and pass
the allele on.
African people are brought to America.
The Europeans come to America.
Now 1 in 12 people of African descent in the
United States has the sickle cell allele.
Now 1 in 25 people of European descent in
the United States has the cystic fibrosis allele.
Use the diagrams to answer the questions.
1. The allele for which disease protects people from malaria?
2. How do the bacteria for typhoid enter an individual?
sickle cell disease
through the digestive system
3. How does the cystic fibrosis gene help protect people from typhoid? The protein
produced by the CF allele prevents the typhoid bacterium from entering the cells of
the digestive system.
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Chromosomal Disorders
Answer the questions.
1. What is nondisjunction? Nondisjuction is a condition in which homologous
chromosomes fail to separate.
2. What happens if nondisjunction takes place during meiosis? (Hint: Remember that
meiosis produces gametes, or sex cells.) If nondisjunction occurs during meiosis,
gametes with an abnormal number of chromosomes may result.
3. Suppose a sperm cell with the normal haploid number of chromosomes fertilizes an egg
cell that does not have the normal haploid number of chromosomes. Will the offspring
have the normal diploid number of chromosomes? Explain your answer.
No. Since one gamete—the egg—did not have the normal haploid number of
chromosomes, when the two gametes join in fertilization, the resulting zygote will not
have the normal diploid number.
4. What is trisomy? a condition in which an individual is born with three copies of a
chromosome
The picture below shows one complete set of human chromosomes. Look at the picture, and
then answer the questions.
5. Is this person male or female? How do you know? Male, because there is one
X chromosome and one Y chromosome.
6. If the person had Klinefelter’s syndrome, how would this picture be different?
The person would have an extra X chromosome.
7. People with Down syndrome have an extra chromosome in one pair. What is the number
21
of the affected pair of chromosomes?
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14.3 Studying the Human Genome
Lesson Objectives
Summarize the methods of DNA analysis.
State the goals of the Human Genome Project and what we have learned so far.
BUILD Vocabulary
A. The chart below shows key terms for the lesson with their definitions. Complete the chart
by writing a strategy to help you remember the meaning of each term. One has been done
for you.
Term
Definition
How I’m Going to Remember
the Meaning
Bioinformatics
A field of study that combines
molecular biology and
information science
Bio- reminds me of biology. Informatics reminds
me of information science.
Gel
electrophoresis
A procedure used to separate
and analyze DNA fragments
by placing a mixture of DNA
fragments at one end of a
porous gel and applying an
electrical voltage to the gel
Genomics
The study of whole genomes
Electro- reminds me of electricity, -phore
reminds me of porous, and -sis is the ending to analysis.
Genomics and genome both come from
gene. Genomics is the study of genomes.
Restriction
enzyme
An enzyme that cuts DNA
A restriction can cut into something. A
restriction enzyme cuts DNA.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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BUILD Understanding
Preview Visuals Looking at the visuals before you read provides clues about what you
are going to learn. Visuals include photographs, charts, graphs, and diagrams. Look at the
diagram of how scientists manipulate DNA. Read the captions and all the labels. Write three
questions you have in the left column of the chart. As you read, write answers in the right
column. The first one has been done for you.
Sample questions and answers:
Questions I Have
Answers I’ve Found
1. How do scientists cut DNA?
1. with a restriction enzyme
2. How do scientists separate DNA?
2. through gel electrophoresis
3. Why is it important to know base
3. so that we can study specific genes
sequences in DNA?
Manipulating DNA
DNA is a very large molecule. Scientists must break it into smaller parts to study it. They
use enzymes, called restriction enzymes, to do this. Then they use a technique known as
gel electrophoresis. The technique allows scientists to separate and analyze the differentsized pieces.
restriction enzymes
1. Scientists cut DNA by using
2. Scientists separate DNA strands using a technique called
.
gel electrophoresis
.
3. Find a partner. With your partner, put the following sentences in order to describe how
scientists manipulate DNA. Write the letters in order in the flowchart below.
A. Scientists add a dye-labeled base to the strand.
B. DNA fragments are put into a porous gel.
C. The fragments separate and appear as bands on the gel.
D. Restriction enzymes cut DNA molecules.
E. An electric voltage moves the DNA fragments across the gel.
D
B
E
C
A
4. What information can scientists get from separating strands of DNA?
Sample answer: They can learn about different mutations and how different strands
can cause different diseases or traits.
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Chapter Review
Use the clues and words to help you write the vocabulary terms from the chapter in the
blanks. You may use a word once or not at all.
karyotype
nondisjunction
genomics
bioinformatics
genomics
1. the study of whole genomes
2. an error in meiosis in which homologous chromsomes fail to separate nondisjunction
3. a picture that shows a complete set of chromsomes, grouped together
karyotype
in pairs
Answer the following questions.
4. Which of the following is NOT an example of nondisjunction?
A. Down syndrome
B. Klinefelter’s syndrome
C. Turner’s syndrome
D. cystic fibrosis
5. A gene that is only found on the X or Y chromosome is known as a
sex-linked gene
6. Which statement best describes inheritance in humans?
A. Offspring inherit one allele for each gene from both parents.
B. Offspring inherit one gene for each allele from both parents.
C. Offspring inherit two alleles for each gene from both parents.
7. Complete the concept map with these phrases: genetic disorders, sickle cell disease,
Huntington's disease, helps prevent typhoid, helps prevent malaria.
Genetic disorders
Sickle cell
disease
Cystic
fibrosis
Helps prevent
malaria
Helps prevent
typhoid
Huntington’s
disease
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.
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Taking a Standardized Test
Test-Taking Tip: Anticipate the Answer
When you take a test, read the question slowly. Don’t look at the answer choices yet. Try to
think of a possible answer for the question. Once you’ve thought of an answer, look at your
choices. Do you see a match?
Read the following question. Do not read the answer choices. Think of a possible answer.
For a female to be colorblind, she must inherit the allele for colorblindness from
A. her mother only.
B. her father only.
C. both her parents.
D. neither of her parents.
Step 1 What is the question asking? The question is asking you to decide which parent
passed on the trait for colorblindness, a sex-linked genetic disorder.
Step 2 You know that colorblindness is a sex-linked disorder, and the allele that
controls the disorder is recessive. It appears on the X chromosome. Females have two
X chromosomes. For a female to inherit the disorder, the allele must be present on both
X chromosomes.
Step 3 Think about how you would answer the question. Then read the answer choices.
You know that a female must inherit the gene from both parents. The answer C matches what
you know. It is the correct answer.
Self-Test
Practice what you have learned by answering the questions. Read the question and think of
an answer first. Then read your choices and circle the answer that is the best match.
1. Hemophilia is a recessive sex-linked genetic disorder. A woman is a carrier for
hemophilia. Her husband does not have hemophilia. What are the chances that one of
their daughters will have hemophilia?
A. 0%
B. 25%
C. 50%
D. 100%
2. A man with hemophilia marries a woman who does not have the allele for hemophilia.
Which statement is true of their children?
A. Their daughters will have hemophilia.
B. Their daughters will carry the hemophilia trait.
C. Their sons will have hemophilia.
D. Their sons will carry the hemophilia trait.
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3. A woman is a carrier for hemophilia. Her husband has hemophilia. What are the chances
that their sons will have hemophilia?
A. 0%
B. 25%
C. 50%
D. 100%
4. What was the main goal of the Human Genome Project?
A. to cure sex-linked genetic disorders
B. to learn how to separate DNA
C. to educate people about codominant alleles
D. to sequence all of the base pairs of the human genome
5. The Human Genome Project led to the new study of
A. genetics.
C. genoethics.
B. genomics.
D. bionomics.
6. Human blood types follow which of the patterns of inheritance listed below?
A. simple dominance
C. sex-linked inheritance
B. codominant inheritance
D. none of the above
7. What is the genotype for someone with the AB blood type?
C. IAIB
A. IAIA
B. IBIB
D. ii
Short-Response Question
Answer the following question in two or three sentences.
8. What might be an ethical concern surrounding the results of the Human Genome Project?
Sample answer: Someone might be concerned that prospective parents would try to
use the information found in their genome to choose the hair and eye color of their
children or to create smarter or stronger babies.
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Genetic Engineering
Science as a Way of Knowing
Q: How and why do scientists manipulate living DNA in living cells?
Chapter Summary
The diagram below shows what you will read about in this chapter and how the chapter is
organized. Study the diagram. Then answer the questions that follow.
15.1 Selective
Breeding
Selective breeding
Increasing variation
Copying DNA
15.2 Recombinant
DNA
Changing DNA
Transgenic organisms
Agriculture and industry
15.3 Applications
of Genetic
Engineering
Health and medicine
Personal identification
Profits and privacy
15.4 Ethics and
Impacts of
Biotechnology
Safety of transgenics
Ethics of the new biology
genetic engineering
1. What is this chapter about?
2. In which lesson do you expect to learn how scientists increase genetic variation? Lesson 1
3. What do you expect to learn in Lesson 2? Sample answer: I expect to learn how
scientists combine DNA.
4. In Lesson 4, you will learn that some people think we should not eat genetically modified
foods. What do you think these people are worried about? Sample answer: They are
concerned about the safety of GM foods.
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15.1 Selective Breeding
Lesson Objectives
Explain the purpose of selective breeding.
Explain how people increase genetic variation.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the chart
by writing a strategy to help you remember the meaning of each term. One has been done
for you.
Term
Definition
How I’m Going to Remember
the Meaning
Biotechnology
The application of technology to living
things
Bio- means “life.” Biotechnology
is using technology with living
things.
Hybridization
Process in which two individuals who
are not alike are bred together to
combine the best traits of both
Inbreeding
The continued breeding of individuals
with similar traits
With inbreeding, you stay in
a group of individuals with
similar traits.
Selective
breeding
A process in which only individuals
with wanted traits are allowed to
reproduce
Selective means “choosy.” Selective
breeding means that you choose the
traits you want to breed.
Hybrid cars are combinations of
electric and gas cars.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
Note: Students should highlight terms and definitions used throughout the chapter.
BUILD Understanding
KWL Chart A KWL chart will help you to get the most out of your reading. In the first
column, write what you already Know about the topic. In the second column, write what you
Want to find out. In the last column, write what you have Learned after reading the lesson.
Make a KWL chart for Lesson 1. An example is shown below.
K
(What I know)
Some fruits are hybrids.
W
(What I want to know)
What is hybridization?
L
(What I learned)
Hybridization is combining
two individuals with different
characteristics.
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Selective Breeding
In selective breeding, a person decides which traits he or she would like an animal to have.
The breeder then chooses a male animal and a female animal with those traits and breeds
them. The breeder expects that their offspring will have the same traits.
Follow the directions.
1. Identify the parents you would select in order to breed offspring with the traits listed.
Male Rabbits
Female Rabbits
1
5
3
2
6
4
7
8
Offspring Traits
Parents
black fur, floppy ears
3 and 5
white fur, short ears
2 and 7
black fur, short ears
4 and 8
white fur, floppy ears
1 and 6
Answer the questions.
2. A breeder breeds rabbits 2 and 8. What trait is the breeder most likely interested in? Circle
the correct answer.
black fur
short ears
3. A breeder is only interested in rabbits with short ears and black fur. Which two rabbits
would he breed together? Circle the correct answer.
4 and 8
3 and 8
4. A person breeds rabbits 2 and 8. Which trait is the breeder trying to select for—ear structure
or fur color? Explain your answer. The breeder is probably trying to select for ear
structure, because the two rabbits have the same ear structure (short ears).
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15.2 Recombinant DNA
Lesson Objectives
Explain how scientists manipulate DNA.
Describe the importance of recombinant DNA.
Define transgenic and describe the usefulness of some transgenic organisms to humans.
BUILD Vocabulary
A. The chart below shows key words from the lesson with their definitions. Complete the chart
by writing a strategy to help you remember the meaning of each term. One has been done
for you.
Term
Definition
How I’m Going to Remember
the Meaning
Clone
A member of a population of
genetically identical organisms
that come from a single cell
C, A clone is a genetic copy.
Genetic
marker
A gene that makes it possible
to know which bacteria carry
recombinant DNA plasmids
I use a marker to highlight something. A
genetic marker is something used to highlight
the bacteria plasmid.
Plasmid
A small circular DNA molecule
found in some bacteria
Recombinant
DNA
DNA made by combining DNA
from different sources
Recombinant = combined
Transgenic
A term used to refer to organisms
that carry genes from other
organisms
Trans- means “across.” Transgenic
organisms carry genes across from other
organisms.
A plasmid molecule is circular like a
plate.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
Check students' questions and answers for relevance and accuracy.
BUILD Understanding
Preview Visuals Previewing visuals and taking notes about them can help you remember
what you read and review for tests. Visuals include photographs, charts, graphs, and
diagrams. Preview each visual in Lesson 2. In your notebook, write one question about each
visual. As you read the lesson, try to find answers to your questions.
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Copying DNA
When Douglas Prasher wanted to find the specific gene that makes the Pacific Ocean jellyfish
glow, he used the Southern blotting method. The flowchart below shows the steps in the
Southern blotting method.
Follow the directions.
1. Use the sentences in the box to complete the flowchart.
Bands on the gel are stopped by blotting to filter paper.
DNA fragments are separated by gel electrophoresis.
Radioactive probes bind to DNA fragments with complementary base sequences.
DNA fragments
Bands on the gel
Radioactive probes
are separated by
are stopped by
bind DNA fragments
gel electrophoresis.
blotting to
with complementary
filter paper.
base sequences.
Answer the questions.
2. Before the DNA fragments are separated, what happens?
A. Filter paper is used.
B. The DNA is cut using restriction enzymes.
3. What type of probes are used to bind DNA fragments with complementary sequences?
gel bands
DNA probes
radioactive probes
4. The filter paper is placed in a tray of
A. alkaline solution.
B. DNA fragments.
C. base sequences.
5. Today, scientists are more likely to search for genes in computer databases than to use
the Southern blotting method. Why do you think use of databases is more common?
Sample answer: The databases have the complete genomes of many different species,
so it is quicker and less expensive to check the databases.
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Changing DNA
Combining DNA Fragments The diagram below shows how recombinant DNA is
formed by combining DNA from two different sources.
Follow the directions.
1. Use the phrases in the box to label the diagram. Some phrases will be used more than once.
cut by restriction enzyme
DNA fragments join
recombinant DNA
Cut by restriction enzyme
sticky end
DNA ligase
Cut by restriction enzyme
G AA T T C
G AA T T C
C T T A A G
C T T A A G
DNA fragments join.
Sticky end
G
AA T T C
C T T A A
G
Sticky end
DNA ligase
G AA T T C
C T T A AG
recombinant DNA
Answer the questions.
2. Circle the correct answer. DNA fragments are joined at
sticky ends.
A ends.
restricted ends.
3. Circle the correct answer. The restriction enzyme cut each DNA sequence at
sequences.
the same
different
4. What enzyme is used to connect the two sequences of DNA?
DNA ligase
5. Is the following statement true or false? Recombinant DNA technology makes it possible
to change the genetic composition of living organisms.
true
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Changing DNA
Plasmids and Genetic Markers Plasmids are small circular pieces of bacterial DNA.
Plasmids are cut using restriction enzymes. A foreign gene is inserted into the plasmids. The
plasmids, which now include recombinant DNA, are then placed into other bacteria cells.
This process is shown in the diagram below.
Follow the directions.
1. Use the terms in the box to label the diagram.
plasmid
recombinant DNA
transformed bacterium
Bacterial
Chromosome
Bacterial
Cell
plasmid
DNA cut with
restriction
enzyme
human gene
recombinant DNA
untransformed bacterium
transformed bacterium
Answer the questions.
2. What type of gene is inserted into the plasmid? Circle the correct answer.
human gene
bacterial cell
3. The recombinant DNA is added to a(n)
answer.
untransformed
bacterium. Circle the correct
transformed
4. Why might a scientist insert a gene that codes for a human growth hormone into bacteria
cells? The bacteria would be able to produce the human growth hormone, which could
then be used in gene therapy.
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15.3 Applications of Genetic Engineering
Lesson Objectives
Describe the benefits of genetic engineering as they relate to agriculture and industry.
Explain how recombinant DNA technology can improve human health.
Summarize the process of DNA fingerprinting and explain its uses.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
DNA
fingerprinting
Analysis of sections of DNA that have
little or no known function but vary widely
from one individual to another, in order to
identify individuals
DNA
microarray
Analysis of genes to determine which are
active and which are inactive in a cell
Forensics
The scientific study of crime-scene
evidence
Gene
therapy
How I’m Going to Remember
the Meaning
The process of changing a gene to treat
a medical disease or disorder
Fingerprints are used to identify
people, and DNA fingerprinting
uses DNA to identify people.
An array is a large group of
things. Scientists study the DNA
microarray to see which genes in
a large group are active and which
are not.
Forensics television shows deal
with using science to solve crimes.
Therapy is another way of saying “medical
treatment.” Gene therapy is a way to
treat a medical disease by changing
a gene.
B. As you work through this lesson, you may find these terms in the activities. When you
write a key term or a definition, highlight the term or the definition.
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BUILD Understanding
Main Idea and Details Chart Taking notes is a way to organize the information you
read. One way to take notes is to keep track of main ideas and details.
As you read the lesson, fill in the chart below with details each support each main idea.
Main Ideas
Details
Agriculture and industry
GM crops, GM animals
Health and medicine
preventing disease, medical research,
treating disease, genetic testing, and
examining active genes
Personal identification
DNA fingerprinting, forensics
Agriculture and Industry
GM Crops Genetically modified (GM) crops have been used as part of our food supply for
about two decades. By changing plants, farmers can make them stronger. Some GM plants
are less likely to be destroyed by insects or infections. The table below shows some possible
genetic modifications in plants. Some of these changes have already been made. Some have
not been made.
Fill in the table.
Genetically Engineered
Plant Change
Why Would This Be a Good Change?
Kills any insect that eats it
The plant would not be eaten by insects.
Not affected by weed killers
Sample answer: The plant would not be destroyed when
poisonous chemicals were sprayed.
Does not get viral infections
Sample answer: The plant would be able to survive infections that could kill it.
Grows fruit that is slow to rot
Sample answer: The fruit would always be good and able
to be sold.
Grows plastic
Has extra vitamin A
Sample answer: Plastic could then be produced cheaply.
Sample answer: The plant’s products would help people
with vitamin-A deficiencies.
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Health and Medicine
Gene Therapy Gene therapy is the process by which genes that cause a disorder are
replaced by normal, working genes. Researchers have tried to carry out gene therapy by using
viruses to insert the normal DNA into the affected cells. The diagram below shows how a
virus might be used to deliver a gene to a bone marrow cell.
Bone marrow cell
Nucleus
Normal gene
1
Chromosomes
Virus
2
3
Arrange the following steps in the correct order.
2
Virus infects human cell.
1
Normal gene is inserted into viral DNA.
3
Virus delivers its DNA to a human cell.
Answer the question.
1. Why are viruses used in gene therapy? Viruses have the ability to deliver the desired
DNA to the host cell. Viral DNA can enter the DNA of the host organism.
Genetic Testing Decide whether each person would benefit from genetic testing. Circle the
correct answer.
2. Jorge and Ana want to have children. However, Ana’s brother has hemophilia. Can Ana
benefit from genetic testing?
yes
no
3. Jules’s dad died from influenza. Jules wonders if he will die from the same thing. Can Jules
benefit from genetic testing?
yes
no
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Personal Identification
No two people are genetically exactly like one another, except for identical twins. DNA
fingerprinting is a method used to identify people based on their DNA. DNA fingerprinting
has helped solve crimes and convict criminals. It has also helped prove that people are
innocent of a crime.
Sa
m
pl
Sa e 1
m
p
Sa l e 2
m
p
Sa l e 3
m
p
Ev le 4
id
en
ce
Look at the DNA fingerprints below. Then answer the following questions.
1. The DNA fingerprint labeled Evidence was left by a criminal at a crime scene. Police have
four different suspects. They took samples of the DNA of each of the four suspects. Which
sample 2
sample matches the evidence?
2. Could sample 1 and sample 2 come from identical twins? Explain your answer. No. The
banding patterns in the two samples are different, so the two people who contributed
the sample do not have identical DNA.
Decide if the following statements are true or false. If a statement is false, tell why.
3. Mitochondrial DNA is passed directly from father to child. false; Mitochondrial DNA is
passed directly from mother to child.
4. DNA evidence can be used to solve crimes, convict criminals, and free people who were
true
wrongfully convicted.
5. Y-chromosome analysis can be used to determine paternal ancestry in males only.
true
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Inquiry Into Scientific Thinking
Genetically Modified Crops in the United States Since 1996, the number of
genetically modified crops in the United States has risen. The graph below shows this trend
for two genetically modified traits in soybeans, cotton, and corn. One trait is herbicide
tolerance (HT), which is the ability of a crop plant to survive when the farmer uses weedkilling chemicals. The other trait is insect resistance (Bt), which is the ability of a crop plant to
resist being eaten by insects.
Study the graph and then answer the questions.
Percent of Acres
Genetically Modified Crops in the U.S.
100
HT soybeans
HT cotton
H
Bt cotton
B
HT corn
H
Bt corn
B
80
60
40
20
0
06
20
04
20
02
20
00
20
98
19
96
19
Year
Source: U.S. Department of Agriculture Economic Research Service Data Sets
1. What variable is shown on the x-axis of the graph (the horizontal axis)?
the year to which the data apply
percentage of cultivated acres
2. What variable is shown on the y-axis (vertical axis)?the
_______________________________
that are planted with the genetically modified crop
3. The graph shows only three crops—soybeans, cotton, and corn. Why, then, are there
five lines, not three? (Hint: Carefully read the label for each graph line. Remember the
meanings of HT and Bt.)
Cotton and corn each have two lines: one line for the crop modified to be
herbicide-tolerant (HT), and a second line for the crop modified to be resistant to
insects (Bt).
4. In your own words, describe what the graph shows about genetically modified crops.
Between 1996 and 2006, the cultivation of GM crops increased significantly.
5. Which genetically modified crop was most widely grown in 2000?
6. Between 2004 and 2007, which GM crop increased the most?
HT soybeans
HT corn
By what percent of acres did this crop increase between those years? (Hint: Find the
percent of acres for that crop in 2004. Subtract that number from the percent of acres for
that crop in 2007.)
about 35
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15.4 Ethics and Impacts
Lesson Objectives
Describe some of the issues that relate to biotechnology.
Identify some of the pros and cons of genetically modified food.
Describe some of the ethical issues relating to biotechnology.
BUILD Understanding
Two-Column Table Think about the ethical issues—the pros and cons—involved in
genetic engineering as you read Lesson 4. Pros are positive points. Cons are negative points.
Write the positive points about genetic engineering in the left column. Write the negatives in
the right column. One has been done for you.
Pros and Cons of Genetic Engineering
Pros
Cons
Add nutrients to foods.
Sample answers: Identify remains of
soldiers; produce crops with higher yields;
possibly treat genetic diseases
Sample answers: possibility of
threatening beneficial insects; privacy
issues; patents forcing small farmers out
of business
CHAPTER
A Case of Mistaken Identity Suppose you are collecting evidence at a burglary
crime scene. Make a list of the different types of evidence you might collect. Circle
evidence that could be tested using DNA fingerprinting.
Students' lists should show a variety of evidence types including hair, blood, and urine,
along with other evidence that may not
contain DNA, such as weapons, bullets, and
evidence of a break-in.
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Profits and Privacy
Genetic engineering raises some ethical concerns. Some people think it is safe, while others
think it is dangerous. In addition, some people worry about individual privacy. The chart
below lists some ethical issues involved with genetic engineering.
Follow the directions.
1. Fill in the chart by saying if you agree or disagree and why.
Ethical Issue Statement
Agree or Disagree?
It is a good idea for
pharmaceutical companies
to patent their genetic
research.
Explanation
Students' answers will vary. Check that
explanations include arguments from the
text as well as students' own opinions.
The U.S. military requires
all personnel to submit
DNA samples.
GM foods are good.
GM foods are not safe.
Circle the best answer.
2. Which of the following is not an ethical issue?
A. using genetic engineering to cure disease
B. using genetic engineering to make “super crops”
C. using genetic engineering to make “super babies”
D. using genetic fingerprinting to prevent someone from getting a job
3. How does the Genetic Information Nondiscrimination Act protect people?
A. It protects people from discrimination based on their genetic information.
B. It provides genetic replacements for people who have gene problems.
Answer the question.
4. DNA evidence taken from crime scenes is added to a database. Do you think that is a good
idea? Give a reason for your answer.
Evaluate students' answers for clarity and logic.
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Chapter Review
Draw a line to match each definition to the vocabulary term from the chapter.
selective breeding
clone
gene therapy
inbreeding
transgenic
1. an organism that carries genes from another organism
2. member of a population that is genetically identical
and came from a single cell
3. breeding individuals with similar traits
4. allowing only individuals with desired traits to breed
5. the process of changing a gene to treat a medical
disease or disorder
Answer the questions.
6. Which of the following is not a type of selective breeding?
A. inbreeding
C. adding mutations
B. hybridization
D. Southern blotting
7. Recombinant DNA is DNA that comes from
A. unhealthy organisms.
B. very healthy organisims.
C. two different organisms.
D. human-made organisms.
8. Choose terms related to recombinant DNA from the box below to complete the concept map.
transgenic
genetic marker
inbreeding
clone
hybridization
plasmid
plasmid
transgenic
Recombinant
DNA
genetic marker
clone
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Taking a Standardized Test
Test-Taking Tip: Preview the Test
Before you begin taking a test, glance over the whole test. Look at the types of questions and
the total number of questions before starting so that you know what to expect.
Step 1 Skim the test questions. Before taking a test, look over each of the questions
quickly. Pay attention to the types of questions that are on the test: fill-in, multiple-choice, or
essay. Notice what the questions are about. Begin thinking about those topics.
Step 2 Decide which questions you want to answer first. Answer the questions you are
most comfortable with first. You should be able to answer these questions quickly.
Step 3 Answer the remaining questions. Answer the questions you are least comfortable
with last. You should have plenty of time for these questions since you answered the “easy”
questions first.
Self-Test
Practice what you have learned by answering the following questions. Preview the test first.
Begin with the questions you are comfortable with. Then, answer the remaining questions.
Circle the correct answer.
1. Which of the following is not an example of a genetically engineered organism?
A. moss that grows in the wild
B. bacterium that produces human growth hormone
C. Dolly the sheep
D. golden rice
2. What type of technology can help identify a person?
A. DNA fingerprinting
B. gene marking
C. polymerase chain reaction
D. GM crops
3. Forensic scientists can study DNA from
A. blood samples.
B. sperm.
C. tissue.
D. all of the above.
4. Plasmids are found in which type of cells?
A. bacteria cells
B. cat cells
C. human cells
D. plant cells
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5. What is one reason to allow cloned animals into the food supply?
A. We do not know if cloned animals are safe to eat.
B. It is too expensive to clone animals.
C. Cloning will allow breeders to duplicate desirable traits.
D. Cloning will require more time for food to be tested.
6. Which disease could possibly be prevented through genetic testing?
A. colds
B. cystic fibrosis
C. influenza
D. Lyme
7. Which statement is true about DNA fingerprinting?
A. DNA fingerprinting can treat genetic diseases.
B. DNA fingerprinting can be used to help criminals.
C. DNA fingerprinting can make plants more resistant to disease.
D. DNA fingerprinting can be used to identify family relationships.
8. Lionel breeds dogs. He only wants dogs with short, brown fur. Which of the following
dogs should Lionel not use for breeding?
A. a dog with long, brown fur
B. a dog with short, brown fur
C. a dog with long, white fur
D. a dog with short, white fur
Short-Response Question
Answer the following question in two or three sentences.
9. Do you think genetic engineering of food crops is a good idea or not? Explain your
answer.
Sample answers: No, I think it is dangerous. We do not know the health implications
of eating genetically modified foods. There have not been enough studies on their
safety. OR: Yes, genetically engineered foods can help reduce food shortages and
starvation. They can also improve the nutrient levels in foods.
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Darwin’s Theory of Evolution
Evolution
Q: What is natural selection?
Chapter Summary
The diagram below shows what you will read about in this chapter and how the chapter is
organized. Study the diagram. Then answer the questions that follow.
Darwin’s epic journey
16.1 Darwin’s Voyage
of Discovery
Observations aboard the Beagle
An ancient and changing Earth
16.2 Ideas That
Shaped Darwin’s
Thinking
Lamarck’s evolutionary hypothesis
Population growth
Artificial selection
Evolution by natural selection
16.3 Darwin Presents
His Case
Common descent
Biogeography
16.4 Evidence of
Evolution
The age of Earth and fossils
Comparing anatomy and embryology
Genetics and molecular biology
Testing natural selection
1. In which lesson do you expect to learn about ideas that influenced Darwin?
2. Another man with ideas about evolution was
2
Lamarck
3. In which lesson do you expect to learn the details of Darwin’s theory of evolution?
.
3
4. What evidence supports Darwin’s theory of evolution? biogeography; the age of Earth
and fossils; comparisons of anatomy and embryology; genetics and molecular biology;
and tests of natural selection in nature
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16.1 Darwin’s Voyage of Discovery
Lesson Objectives
State Charles Darwin’s contribution to science.
Describe the three patterns of biodiversity noted by Darwin.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Evolution
The process by which modern
organisms have changed over
long periods of time from their
common ancestors
The root of evolution is evolve, which means “to
change,” so evolution is the process by which
organisms change.
Fossil
A preserved remain or trace of
a once-living organism
I know what dinosaur fossils are, so I can use
that information to remember that a fossil
is the remains of a once-living organism.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
Note: Students should highlight terms and definitions used throughout the chapter.
BUILD Understanding
Preview Visuals Previewing visuals and taking notes about them can help you remember
what you read and review for tests. Visuals include photographs, charts, graphs, and
diagrams.
Before you read Lesson 1, look at the visuals. Descriptions of three visuals have been written
in the left column of the table below. In the right column, write a question about the visual. As
you read, try to answer your questions.
Sample answers:
Description
Question
A map that shows Darwin’s voyage on the
Beagle
What is so important about the Galápagos Islands?
A map of the Galápagos Islands with photos of
tortoises
Why do the tortoises look different?
Drawings of an armadillo and fossil glyptodont
Are the armadillo and glyptodont related?
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Observations Aboard the Beagle
When Charles Darwin visited the Galápagos Islands, he discovered that similar animals living
on separate islands had different features.
Compare the diagrams of tortoises.
Hood Island tortoise
Isabela Island tortoise
Answer the questions.
1. The tortoises eat plants. On one island, plants grow very close to the ground. Which
island is this most likely to be? Circle the correct answer.
Isabela Island
Hood Island
2. Explain your answer to question 1. Why did you choose the island that you did?
Sample answer: The Isabela Island tortoise has a short neck, so it cannot reach taller
vegetation. It probably eats plants that grow close to the ground.
3. Galápagos tortoises are certainly not the only organisms that show variations. Describe
variations you have observed among another group of organisms, like plants, butterflies,
birds, or fish.
Check students’ answers for logic, clarity, and completeness.
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16.2 Ideas That Shaped Darwin’s Thinking
Lesson Objectives
Identify the conclusions drawn by Hutton and Lyell about Earth’s History.
Describe Lamarck’s hypothesis of evolution.
Describe Malthus’s view of population growth.
Explain the role of inherited variation in artificial selection.
BUILD Vocabulary
A. The chart below shows a key term from the lesson with its definition. Complete the chart
by writing a strategy to help you remember the meaning of the term.
Term
Definition
Artificial
selection
Selection in which nature
provides variation of traits,
but humans decide which are
the most useful and breed
organisms to have those traits
How I’m Going to Remember
the Meaning
Artificial means “not in nature,” so I
know that artificial selection is made by
humans.
B. As you work through this lesson, you may find this term in the activities. When you need
to write the key term or its definition, highlight the term or the definition.
BUILD Understanding
Main Idea and Details Chart As you read a lesson, use all the green headings as the
main ideas. Write them in the Main Idea column. Write details about each main idea in the
Supporting Details column. One has been done for you.
Main Idea
Supporting Details
An Ancient, Changing Earth
James Hutton said that Earth was extremely old.
Lamarck’s Evolutionary Hypothesis
Lamarck came up with a hypothesis
about evolution before Darwin, but it
was incorrect.
Population Growth
When populations grow unchecked,
resources become scarce.
Artificial Selection
Breeders and farmers select useful
traits among natural variations in their
crops or livestock.
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Lamarck’s Evolutionary Hypotheses/
Population Growth/Artificial Selection
Like all scientists before and after him, Darwin was inspired and influenced by the ideas of
others.
humans
nature
Malthus
geology
artificial
Lamarck
Hutton
Use the clues below to complete the crossword puzzle with words from the box.
1
N
2
A
R
T
I
F
I
C
I
A
T
4
E
M
M
5
R
G
L
A
U
6
3
H
A
O
L
O
G
U
Y
H
A
N
S
R
C
T
7
M
U
T
T
O
N
K
U
S
ACROSS
2.
selection
5. In artificial selection, these select the useful variations.
6. Darwin was influenced by Lyell’s book Principles of
.
7. One of two scientists who recognized that the Earth was very old.
DOWN
1. In natural selection, this determines the variations.
3. His theory of evolution was based on acquired traits.
4. Darwin was inspired by his ideas on population growth.
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16.3 Darwin Presents His Case
Lesson Objectives
Describe the conditions under which natural selection occurs.
Explain the principle of common descent.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
Adaptation
An inherited characteristic that
increases an organism’s ability
to survive
Fitness
How well an organism can
survive and reproduce in an
environment
Natural
selection
The process by which
organisms that are most
suited to their environment
survive and reproduce
How I’m Going to Remember
the Meaning
An adaptation is a characteristic that
enables an organism to adapt to its
environment.
I know it is important for me to be physically fit so
I can live longer. Fitness is how well an organism
can survive.
In artificial selection, humans determine
which traits are best, so natural selection
is when nature determines which traits
are best.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
BUILD Understanding
Preview Visuals Before you read the lesson, preview the diagram that shows the process
of natural selection. Describe what the visual helps you understand in the right column of the
table below.
Description
Natural selection in grasshoppers
What It Helps Me Understand
Sample answer: The diagram explains the
process of natural selection, including the
struggle for existence, adaptation, and
survival of the fittest.
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Evolution by Natural Selection
An adaptation is an inherited characteristic that helps an organism survive and reproduce in
its environment. Over time, adaptations become more and more common in the population.
For example, suppose that the water in a pond gets darker over a period of four years. The
diagrams and table below show what might happen to a frog population living in the pond.
Use the diagrams below to complete the table.
Year 2
Year 1
Year 3
Year 4
Adaptations of Frog Populations Over Time
Year
Light-Colored Frogs
Dark-Colored Frogs
1
6
2
2
4
4
3
2
6
4
0
8
Answer the questions.
1. In which year was the number of light-colored frogs greater than the number of darkcolored frogs?
Year 1
2. How did the numbers of light- and dark-colored frogs change over time? The number of
dark-colored frogs increased. The number of light-colored frogs decreased.
3. Which adaptation is best suited to life in the pond in Year 3? Circle the answer.
light coloring
dark coloring
4. How do the dark-colored frogs show “survival of the fittest”? Sample answer: As the
pond water grows darker, the dark-colored frogs are less likely to be seen and eaten
by predators. They are more fit than the light-colored frogs and, therefore, more likely
to survive and reproduce.
5. How is natural selection different from artificial selection? Sample answer: In artificial
selection, humans determine the desired characteristics and only breed animals with
those characteristics. In natural selection, nature determines the desired characteristics and only organisms with these characteristics survive to reproduce.
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16.4 Evidence of Evolution
Lesson Objectives
Explain how geologic distribution of species relates to their evolutionary history.
Explain how fossils and the fossil record document the descent of modern species from
ancient ancestors.
Describe what homologous structures and embryology suggest about the process of
evolutionary change.
Explain how molecular evidence can be used to trace the process of evolution.
Explain the results of the Grants’ investigation of adaptation in Galápagos finches.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Analogous
structures
Body parts that share the
same function but not the
same structure
Biogeography
The study of where organisms
now live and where their
ancestors lived in the past
Homologous
structures
Structures that are shared by
organisms and that have been
inherited from a common
ancestor
Vestigial
structures
Homologous structures that
have little or no useful function
in an organism
An analogy compares two things that are
not the same, so analogous structures
are two body parts that have the same
purpose but not the same structure.
Bio refers to life, and geography refers to land,
so biogeography refers to where organisms live.
Homo- means “same,” so homologous
structures are inherited from the same
ancestor.
A vestige is a trace, so vestigial
structures maintain only a trace of their
original function.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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BUILD Understanding
Concept Map A concept map can help you organize information and show how ideas are
connected. As you read Lesson 4, fill in the concept map below. Some has been done for you.
Biogeography
Evidence
of
Evolution
Fossils
is the
study of
show
iincludes
Comparing
anatomy
includes
looking at
Where organisms live now, where
their ancestors lived.
How organisms have changed
over time
Homologous
structures
and
Embryology
Genetics
Tests of
natural
selection
like
The Grants’ Study of Galápagos finches
The Age of Earth and Fossils
In the fossil record, an intermediate form is a fossil that shows some characteristics of an
earlier related organism and some characteristics of a later related organism. The diagrams
below show organisms whose fossils make up part of the fossil record. The organisms are in
order from oldest (organism 1) to most recent (organism 6).
Follow the directions. Use the diagrams to answer the questions.
1. Draw an animal that might have been an intermediate form between organism 1 and
organism 3.
2. Draw an animal that might have been an intermediate form between organism 4 and
organism 6.
Organism 1
Organism 4
Students’ drawings may show
an elongated shell and/or
slightly longer tentacles.
Organism 2
Students’ drawings may
show a somewhat more
coiled shell.
Organism 5
Organism 3
Organism 6
3. Describe one change you see between organism 1 and organism 3. The shell grew longer.
4. How might these fossils provide evidence for evolution? Sample answer: They show
changes over time among related organisms.
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Comparing Anatomy and Embryology/
Genetics and Molecular Biology
Darwin’s basic ideas about evolution have been supported by scientific evidence. The chart
below lists some of the evidence of evolution.
Use the words in the box and what you know about the evidence supporting evolution to
complete the chart.
biogeography
embryological development
genetics
Type of Evidence
fossil record
What It Reveals
homologous structures
Different species have similar structures
which have been inherited from a common
ancestor.
embryological development
Animals with backbones have a common
ancestor, as shown by how these organisms
develop before they are born.
fossil record
Intermediate forms show that organisms have
changed over time.
biogeography
Species have adapted over time to local
conditions.
genetics
Almost all organisms share a common genetic
code.
Answer the questions.
1. Give an example of two homologous body structures. Sample answer: the bones in a
bird’s wing and those in a mammal’s arm
2. What is the difference between a homologous structure and an analogous structure?
Homologous structures result from common descent. They are similar in structure but
not necessarily similar in function. Analogous structures are similar in function but not
structure. Analogous structures are not the result of common descent.
3. How have advances in molecular biology provided evidence for evolution?
Sample answer: We now know that almost all organisms share a nearly identical
genetic code and that many organisms share homologous proteins and genes, such as
Hox genes.
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BUILD Connections
Finch Beak Tools An analogy takes two things that seem to be different and shows how
they can be similar.
Tree Finches
Ground Finches
Pinaroloxias
Platyspiza
This finch feeds on insects, fruit, and nectar.
Its beak works like curved, needle-nose pliers
that are good at probing and grasping at the tip.
This vegetarian finch strips bark from woody
plants with a beak designed to grip and hold
tightly, like a pair of pliers.
Geospiza
Certhidea
This finch feeds on small, exposed insects that it
picks off plant surfaces. Its thin, straight, narrow
beak works like needle-nose pliers or forceps
8
to firmly grasp small objects at the tip.
This finch feeds on large, thick seeds with a
beak that is thick, strong, and sharp. This beak
works like heavy-duty wire cutters to apply
strong pressure and cutting force near its base.
8
8
1. How does comparing the finches’ beaks to tools help you understand how different beak
shapes can help finches? Sample answer: I can see how each beak shape allows the
finch to eat different types of food.
2. Find a partner. Using the analogy, explain to your partner why each species of finch eats
different food.
CHAPTER
Honeycreepers Imagine you work for a travel agency. Design a travel brochure
inviting people to come to Hawaii to see the honeycreepers. Explain why the
honeycreepers provide evidence of evolution. Draw a sketch of your brochure below.
Brochures should include
the ways the honeycreepers provide evidence for
evolution.
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Inquiry Into Scientific Thinking
Why Is There Variation in Peppers? The two main sources of genetic variation
are mutations and gene shuffling. A mutation is any change in a sequence of DNA. Gene
shuffling occurs during gamete formation. It can produce millions of different gene
combinations. Both mutations and gene shuffling increase genetic variation by increasing the
number of different genotypes.
Follow the directions. You will need a pepper (red, yellow, green, or purple) and knife.
1. Cut your pepper into four pieces.
2. Keep one piece for yourself. Exchange the remaining pieces with other students until you
have one piece of each color.
3. Use your senses to compare the peppers. How do they look, feel, and smell?
4. Fill in the chart below.
Color of Pepper
Texture of Pepper
Smell of Pepper
Analyze and Conclude
1. How do the peppers vary? Sample answer: The peppers vary in color, texture, and smell.
2. Why do you think the peppers vary? Sample answer: I think that farmers have used
artificial selection over generations to produce these varieties.
3. What other characteristics of peppers could you compare?
taste, shape, size, seeds
4. If you wanted to grow a new kind of pepper, what characteristics would you like it to
have?
Answers will vary.
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Chapter Review
Use the clues and words to help you write the vocabulary terms from the chapter in the
blanks. You may use a word once, more than once, or not at all.
artificial selection
vestigial structure
1.
Evolution
adaptation
evolution
natural selection
homologous structure
is the study of how living things change over time.
2. Artificial selection is when nature determines the variety of traits, but humans pick
which traits are desirable.
3. An inheritable characteristic that increases an organism’s ability to survive and reproduce
is called a(n)
adaptation
.
vestigial structure
4. The eyes of a blind cavefish are an example of a
.
Answer the questions.
5. Who developed the theory of evolution that includes natural selection? Charles Darwin .
6. Whose book Principles of Geography helped shape Darwin’s ideas about evolution?
A. James Hutton
C. Charles Lyell
B. Jean Baptiste Lamarck
D. Thomas Malthus
7. Use the Venn diagram to compare artificial selection and natural selection.
Natural
Selection
• The environment
chooses desired traits
and affects fitness.
Both
• Variations
are provided
by nature.
Artificial
Selection
• Humans choose
desired traits and
affect fitness.
8. Complete the concept map.
Evidence for
Evolution
includes
tests of
natural selection
in nature
Genetics and
molecular
biology
The fossil record
The geographic
distribution of
living species
Similarities in
anatomy and
embryology
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Taking a Standardized Test
Test-Taking Tip: Come Back to Difficult Questions
If you are taking a long time to answer a question, mark it and come back to it later.
Read the following question and answer choices.
Which of the following is NOT a pattern of biodiversity noted by Darwin?
A. Species vary globally.
C. Species vary greatly.
B. Species vary locally.
D. Species vary over time.
Step 1 Before starting the test, decide how long you want to spend on each question.
Look over each question quickly to determine how much time you think you will need to
answer each one. Make sure to leave enough time at the end of the test to review your work
before handing it in.
Step 2 If you are having trouble answering a question, move on. All of the answers in the
question above seem like they could be correct. Thinking this through can take a great deal of
time. If you are spending more time than you thought you should on a question, stop. Put a
mark next to the question so you can find it easily later. Then, move on to the next question.
Step 3 When you have answered the rest of the questions, go back to the questions that
you had difficulty answering. Now return to the question you marked earlier and try to
reason out the answer.
Step 4 Answer the question. You know the answer must be something first noted by
Darwin. Darwin would have noticed on the Beagle that species varied globally and locally. He
also used fossils to discover that species vary over time. So, the correct answer is C, species
vary greatly.
Self-Test
Practice what you have learned by answering the following questions. Circle the correct
answer. If you don’t know the answer to a question or are spending too much time on it,
mark it and move on. You can come back to the question when you have completed the rest
of the test.
1. In a muddy pond, light-colored fish are more likely to be eaten than dark-colored fish.
What is dark coloring an example of?
A. artificial selection
B. fossil evidence
C. adaptation
D. none of the above
2. Darwin realized that members of populations compete for food, living space, and other
necessities. This is known as
A. struggle for existence.
B. variation and adaptations.
C. survival of the fittest.
D. natural selection.
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3. Biogeography is the study of where
A. organisms live now.
B. organisms lived in the past.
C. organisms’ ancestors lived.
D. all of the above
4. Both bats and mosquitoes have wings. This is an example of a(n)
A. analogous structure.
B. homologous structure.
C. vestigial structure.
D. none of the above.
5. Darwin’s theory of evolution is supported by
A. DNA evidence.
B. fossil evidence.
C. embryology.
D. all of the above.
6. Which of the following statements is true?
A. All living cells have different genetic codes.
B. All living cells have a common genetic code.
C. All living organisms have different ancestors.
D. All living organisms have acquired traits that are passed on.
7. What would be a favorable trait for a rabbit trying to avoid predators in a snowy climate?
A. white fur
B. brown fur
C. long ears
D. short ears
8. Which is NOT part of Darwin’s theory of evolution?
A. acquired characteristics
B. common descent
C. natural selection
D. variations and adaptations
Short-Response Question
Answer the following question in two or three sentences.
9. Explain what Darwin meant by the “survival of the fittest.”
Sample answer: Darwin meant that organisms with traits that make them more fit to
survive will be more likely to produce offspring and thus survive as a species.
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Evolution of Populations
Evolution
Q: How can populations evolve to form new species?
Chapter Summary
The diagram below shows what you will read about in this chapter and how the chapter is
organized. Study the diagram. Then answer the questions that follow.
Genetics joins evolutionary theory
17.1 Genes and
Variations
Sources of genetic variation
Single-gene and polygenic traits
How natural selection works
17.2 Evolution as
Genetic Change
in Populations
Genetic drift
Evolution versus genetic equilibrium
17.3 The Process of
Speciation
Isolating mechanisms
Speciation in Darwin's finches
Molecular clocks
17.4 Molecular
Evolution
Gene duplication
d l
Developmental genes and body plans
1. What is this chapter about?
the evolution of populations
2. What are the four main related topics? genes and variations, evolution as genetic
change in populations, the process of speciation, and molecular evolution
3. What topic do you expect to learn more about in Lesson 1? how genetics relates to
evolution
4. In which lesson do you expect to learn about Darwin’s finches?
Lesson 3
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17.1 Genes and Variations
Lesson Objectives
Define evolution in genetic terms.
Identify the main sources of genetic variation in a population.
State what determines the number of phenotypes for a trait.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the chart by
writing a strategy to help you remember the meaning of each term. One has been done for you.
Term
Definition
Allele
frequency
The number of times an allele
appears in a gene pool,
compared to the total number
of alleles in that pool for the
same gene.
Gene pool
A common group of genes,
and all their alleles, shared by
a population
Polygenic
trait
A trait controlled by two or
more genes
How I’m Going to Remember
the Meaning
Frequency means how often something
happens, so allele frequency must relate
to how often an allele appears in a
population.
To carpool means to share a car, and a gene pool is
all the genes shared by a population.
Poly- means “many,” so a polygenic trait
is a trait controlled by more than one gene.
Single-gene
trait
A trait controlled by only one
gene
Single means “one,” so single-gene traits
are traits controlled by only one gene.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
Note: Students should highlight terms and definitions used throughout the chapter.
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BUILD Understanding
Concept Map A concept map helps you see how the topics you read about are related to
one another. Use the words and phrases below to fill in the empty spaces in the concept map.
Genetic recombination
Chromosomes
Genes
Crossing-over
Sources of
Genetic Variation
include
Mutations
Genetic
recombination
involve changes in
happens during
Genes
Chromosomes
Meiosis
Lateral
gene transfer
Crossing-over
CHAPTER
Epidemic Viruses, including flu viruses, have genes. The genes determine the viruses’
traits. What traits might make some viruses better at causing disease than other viruses
are? Write your ideas in the space below.
Accept all reasonable ideas. If students don’t
know what viruses are, consider providing
them with simple information about viruses.
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Single-Gene and Polygenic Traits
Polygenic Traits Some traits are controlled by only one gene. They are called single-gene
traits. Other traits are controlled by two or more genes. They are called polygenic traits.
Human height is an example of a polygenic trait.
Follow the directions.
1. Draw one bar for each height range.
The bar should show how many students
have heights in that range.
2. Draw a curve connecting the tops of
the bars.
Height in cm
Number of Students
155–159
160–164
165–169
170–174
175–179
180–184
185-189
190–194
1
2
6
10
10
6
2
1
Student Heights
Number of Students
12
10
8
6
4
2
0
155–159
160–164
165–169
170–174
175–179
180–184
185–189
190–194
Height (cm)
Answer the questions.
3. Circle the correct answer. What shape is the curve you drew?
bell curve
one-sided curve
irregular curve
4. What is the average height for this population?
A. 155–164 cm
B. 165–174 cm
C. 170–179 cm
D. 185–194 cm
5. Jane and Miguel are both 172 cm tall. Does that mean they have the same genotype?
Why? No. Because height is a polygenic trait, there are many different combinations
of alleles that result in the same height.
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17.2 Evolution As Genetic Change
in Populations
Lesson Objectives
Explain how natural selection affects single-gene and polygenic traits.
Describe genetic drift.
Explain how different factors affect genetic equilibrium.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the chart by
writing a strategy to help you remember the meaning of each term. One has been done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Bottleneck
effect
A change in an allele’s frequency
following a dramatic reduction in
population size
Bottlenecks are much smaller than
the rest of the bottle. The bottleneck
effect happens to populations that
get suddenly small.
Directional
selection
Form of natural selection in polygenic
traits in which the entire curve shifts
because some individuals are more
successful at surviving
Dirc Selec was taller and stronger, so
he was picked.
Disruptive
selection
Form of natural selection in polygenic
traits in which the curve splits in two
because individuals at the two ends
are more successful at surviving than
those in the center
Disty Selec and her friend were at the
two ends of the line, and they did not
get wet at all.
Founder
effect
A change in an allele’s frequency
that occurs as a result of a migration
of a small part of the population
Since they had not found their way back, the
effect was that they started a new group
somewhere else.
Genetic drift
A random change in an allele’s
frequency
Genetic
equilibrium
When all of the alleles in a
population remain the same
Drifting = random motion
Genetic drift = random change
Equilibrium means no change, so
genetic equilibrium is when the
alleles stay the same.
Continued on next page ▶
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254
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Term
Definition
Sexual
selection
The process of selecting a mate based
on traits like strength or color
Stabilizing
selection
Form of natural selection in polygenic
traits in which the center of the curve
stays in the same position because
the individuals in the center are more
successful at surviving
Date
How I’m Going to Remember
the Meaning
I know what natural selection is, so
sexual selection must be related, but
involve choosing males.
Staby Selec always thrives by being in
the center of everything.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
BUILD Understanding
Preview Visuals Previewing visuals and taking notes about them can help you remember
what you read and review for tests. Visuals include photographs, charts, graphs, and
diagrams. As you look at each visual, think about why it may be important to the lesson.
Before you read Lesson 2, look at all the visuals. Write a question about the visuals listed
below. As you read the lesson, try to answer your questions.
Visual
Question
Answer
a chart that shows the effect
of color mutations in lizards
Sample question: What
evolutionary trend does
the chart show?
natural selection of singletrait genes
graphs that show selection on
polygenic traits
Sample question: What are
the three types of selection
that act upon polygenic
traits?
directional, stabilizing,
and disruptive
diagram showing the founder
effect
Sample question: Why is
founding population A so
different from founding
population B?
because they each founded
different populations and
are no longer part of the
same population
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How Natural Selection Works
Natural Selection on Polygenic Traits In most populations, a trait that has higher
fitness leads to greater numbers of organisms with that trait. On the graphs below, dotted
lines show the original population. The solid lines show the population after selection has
taken place.
Follow the directions.
1. Label the graph that shows stabilizing selection.
original
population
Number of Birds in Population
Percentage of
Human Population
2. Label the graph that shows disruptive selection.
original
population
Beak Size
Birth Weight
stabilizing selection
disruptive selection
Answer the questions.
3. With which type of selection do organisms in the middle of the curve have the highest
fitness? stabilizing
4. In disruptive selection, organisms on which part of the curve have the lowest fitness?
middle of the curve
5. How does the curve change in stabilizing selection?
A. The curve becomes shorter and wider.
B. The curve becomes taller and narrower.
C. The curve moves to the right.
6. The plants in an area have either very small or very large seeds. Birds with small beaks can
eat small seeds, and birds with large beaks can eat large seeds. Birds with smaller beaks
and birds with larger beaks become more common than birds with medium beaks. What
type of selection is this?
A. stabilizing selection
B. disruptive selection
C. directional selection
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256
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Date
Evolution Versus Genetic Equilibrium
The Hardy-Weinberg Principle Genetic equilibrium occurs when the allele frequencies
in a population remain the same. If the allele frequencies do not change, the population will
not evolve. The Hardy-Weinberg principle lists the five conditions in which evolution does
not occur in a population.
Read the chart below. Use phrases in the word box to identify each condition that leads to
genetic equilibrium. The first row has been completed for you.
large population
random mating
no natural selection
no mutations
no movement
The Hardy-Weinberg Principle
large population
The more individuals in the population, the
smaller the effect of genetic drift.
no mutations
No changes to genes means new alleles are not
introduced into the population’s gene pool.
random mating
Each individual in a population has the same
chance of passing on its alleles.
no movement
No new alleles are introduced into the
population’s gene pool by new individuals.
no natural selection
No phenotype can have a selective advantage
over another—all individuals have equal fitness.
Read the descriptions below. Use what you know about the Hardy-Weinberg principle to
identify what is happening.
1. Genetic drift strongly affects the population.
A. small population
B. random mating
C. no movement into or out of the population
D. no natural selection
2. Lions with a darker fur color have the same chance to reproduce as lions with a lighter
fur color.
A. large population
C. random mating
B. no mutations
D. no natural selection
3. Fitness is basically the same among individuals in the population.
A. large population
C. random mating
B. no mutations
D. no natural selection
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Inquiry Into Scientific Thinking
Allele Frequency Allele frequency is the number of times an allele occurs compared
to the total number of alleles for that gene in a population. If populations, generation
after generation, keep the same allele frequencies, the population is in Hardy-Weinberg
equilibrium. If allele frequencies change, the population is evolving.
Follow the directions.
1. Choose two different colored pieces of construction paper. Cut out 20 butterfly shapes
from each piece of paper. Decide which color you want to be “dominant.” The other color
is your “recessive” color.
2. Place a large piece of construction paper in your dominant color on the floor. Place 10 of
each of your butterfly colors on the piece of paper. This is Generation 1.
Generation 1
Dominant Color
Recessive Color
5
5
Generation 2
Generation 3
3. Have a partner time you for 5 seconds. Pick up as many butterflies, one by one, as you can.
4. Double the number of each color on the paper. For example, if there are 3 red pieces left,
put 3 more red pieces on the construction paper. This is Generation 2.
5. Repeat steps 4 and 5. This is Generation 3.
Analyze and Conclude
1. Which color has the most pieces in Generation 3?
Probably the “dominant” color
2. How is Generation 3 different from Generation 1? In Generation 1, the population had
an equal number of each color. In Generation 3, however, most of the butterflies
probabaly had the color that was the hardest to see.
3. If the paper shapes were a population of real butterflies, how would the allele frequency in
Generation 3 compare to the allele frequency in Generation 1?
In Generation 3, the frequency of the dominant allele would be greater than it was in
Generation 1.
4. Is evolution occurring in this population? How do you know? (Hint: Use the word allele
in your answer. ) Yes, because the allele frequency is changing.
5. Is the population of butterflies in genetic equilibrium? Explain your answer.
No, because the allele frequency is changing. If the population were in genetic
equilibrium, the allele frequency would remain the same.
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17.3 The Process of Speciation
Lesson Objectives
Identify the types of isolation that lead to the formation of new species.
Describe the current hypothesis about Galápagos finch speciation.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Behavioral
isolation
When two populations have
different behaviors that keep them
from reproducing
It’s just like it sounds—different behaviors
keep groups isolated, or apart.
Geographic
isolation
When two populations are
separated by geographic features,
such as rivers or mountains, that
keep them from reproducing
Reproductive
isolation
Separation of populations so that
they cannot reproduce
Reproduce = have kids
Isolation = alone
Have kids alone? Can’t.
Species
A population or group of
populations whose members can
interbreed and produce fertile
offspring
Since there are all kinds of crossbred
dogs, all dogs must belong to the same
species.
Speciation
The forming of a new species
Temporal
isolation
When two populations reproduce
at different times, so that they
cannot reproduce together
The geography/mountain is so big that
we are isolated/kept apart.
Species + evolution = speciation
Temporal means time, so temporal
isolation = kept apart by a timing issue.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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BUILD Understanding
Compare/Contrast Table Use a compare/contrast table when you want to see the
similarities and differences between two or more processes.
As you read about the different types of reproductive isolation, fill in the table below.
What Leads to Reproductive Isolation
Type of Isolation
Description
when populations cannot mate because they have different courtship rituals
when populations cannot mate because they are separated by geographical features
when populations cannot mate because they mate at different
times
Behavioral
Geographic
Temporal
Populations Become Isolated
Speciation occurs when a new species evolves. Many things contribute to speciation.
Read the chart below. Then, use phrases in the word box to identify each process that leads
to speciation. The first row has been completed for you.
changes in the gene pool
competition
Process
founders arrive
geographic
isolation
changes in the
gene pool
geographic isolation
behavioral isolation
founders arrive
How It Leads to Speciation
A population arrives in a new place.
Populations are separated by a geographic barrier and do not share a gene pool.
Populations evolve new traits in response to natural selection in their environments.
competition
Species evolve in a way that reduces competition between them.
behavioral
isolation
Groups within a population are separated by different courtship rituals.
Answer the questions.
1. Finches prefer to find mates with the same size beaks. Finches in Group A have larger
beaks than those in Group B, so finches from the two groups will not mate. What is this an
example of? behavioral isolation
2. Do populations that are geographically isolated from one another share a gene pool? Why
or why not? No. They are separated by a geographic barrier so they cannot mate with
one another.
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Date
Speciation in Darwin’s Finches
Charles Darwin proposed that the different species of finches on the Galapagos Islands once
had a common ancestor. Over time, he said, natural selection led to each species of finch.
A current hypothesis says that speciation in the Galapagos finches occurred through the
founding of a new population, geographic isolation, changes in the new population’s gene
pool, behavioral isolation, and ecological competition.
Use the phrases in the box to complete the chart.
insects that live inside dead wood
small seeds
large, thick-shelled seeds
Galápagos Islands Finches
Shape of head
and beak
Main food
fruits
insects that
live inside
dead wood
small seeds
large, thickshelled seeds
Feeding
adaptation
parrotlike
beak
uses cactus
spines
pointed
crushing beak
large
crushing beak
trees
trees
ground
ground
Habitat
Answer the questions.
1. How does the large crushing beak help the fourth finch survive? It allows the finch to
crush and eat large seeds.
2. Circle the finch that would be least likely to survive if the insect population decreased.
3. Both the first and second finch live in trees. Suppose one season there is less fruit in the
trees. Which finch is more likely to survive and reproduce?
A. the first finch
B. the second finch
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17.4 Molecular Evolution
Lesson Objectives
Explain how molecular clocks are used.
Explain how new genes evolve.
Describe how Hox genes may be involved in evolutionary change.
BUILD Vocabulary
A. The chart below shows the key term from the lesson with its definition. Complete the chart by
writing a strategy to help you remember the meaning of the term.
Term
Definition
How I’m Going to Remember
the Meaning
Molecular
clock
A model that uses mutation
rates in DNA to estimate the
time that two species have been
evolving separately
Tick Tock
The Molecular Clock
Times evolution from the
Ancestors of Crocs.
B. As you work through this lesson, you may find this term in the activities. When you need
to write the key term or a definition, highlight the term or its definition.
BUILD Understanding
Flowchart A flowchart is a way to show the steps in a process.
Complete the flowchart with the steps in which duplicate genes evolve.
Original gene
Mutation
occurs.
New gene
evolves.
No mutation
Gene stays
the same.
Duplication
of genes
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Molecular Clocks
A molecular clock measures mutation rates in DNA to estimate the time that two species have
been evolving independently. Look at the molecular clock below. You can compare the DNA
sequences in each species to see which are more closely related.
New mutation
Section of DNA in a
common ancestor
1 Mutation
A C GG T A C T A C
A C GG T A C A A C
New mutation
C C GG T A C A A C
A C GG T T C A A C
1 Mutation
New mutation
A T GG T T GA A C
A T GG T T C A A C
Species
C
Species
B
Species
A
Look at the clocks below. The original strand of DNA is shown on both clocks. For each
period of 15 million years, rewrite the strand on both clocks and include a mutation. Each
mutation should be different.
Clock A
Clock B
Sample mutations:
Original species
45 million
years
Original species
C
A
G
T
A
C
A
G
C
T
C
G
G
T
A
C
A
G
C
C
15 million
years
45 million
years
30 million years
C
A
T
T
T
C
A
G
C
T
C
A
T
A
T
C
A
G
A
T
15 million
years
30 million years
Answer the question.
1. On both clocks, which time represents the species that are most closely related to the
original?
A. 15 million years
B. 30 million years
C. 45 million years
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Chapter Review
Use the clues and words to help you write vocabulary terms from the chapter in the blanks.
You may use a word once, more than once, or not at all.
gene pool
species
genetic drift
speciation
molecular clock
species
1. inbreeding members of a population
speciation
2. the formation of a new species
genetic drift
3. An example of random change in an allele frequency
gene pool
4. a common group of genes, and all their alleles,
shared by a population
Answer the questions.
5. Which of the following is not a condition of Hardy-Weinberg equilibrium?
A. genetic drift
C. no mutation
B. large population
D. random mating
6. Natural selection acts on an organism’s
phenotype
.
7. Complete the graphic organizer below.
Reprductive can
ca occur
Isolation
by
Geographic
Isolation
which
means
individuals are separated by
geographic barriers
Behavioral
Isolation
which
w
m
means
individuals develop different
courtship rituals
which
means
individuals reproduce at
different times
Temporal
Isolation
Use the graph to answer question 8.
Number of Birds
in Population
8. The graph below shows which type of natural selection?
A. directional selection
B. stabilizing selection
C. disruptive selection
Beak Size
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Taking a Standardized Test
Test-Taking Tip: Use Visuals to Answer Questions
When a question has a data table or graph with it, look at the visual carefully before and after
you read the question.
Read the following question and answer choices.
Which graph shows stabilizing selection?
A. A
C. C
B. B
D. all of the above
Beak Size
Graph C
Number of Birds
in Population
Graph B
Percentage of
Population
Number of Birds
in Population
Graph A
Beak Size
Birth Mass
Step 1 What is the question asking? This question is asking you to choose which graph
shows stabilizing selection.
Step 2 Read the graph carefully. Decide what the data shows.
Step 3 Read each answer choice carefully.
Step 4 Cross off answer choices that you know are incorrect. For example, you know that
all the graphs cannot show stabilizing selection. You can cross off D.
Step 5 Choose one of the remaining answer choices. Read the graph again. You know that
in stabilizing selection, the bell is more narrow. That means the answer is C.
Practice what you have learned by completing the following questions. For each question, use
the visuals provided. Then circle the correct answer.
Use the graphs above to answer questions 1–3.
1. In Graph A, which individuals are the most fit?
A. those at the lower end of the curve
C. those at the higher end of the curve
B. those at the center of the curve
D. none of the above
2. Which type of selection does Graph A show?
A. directional selection
C. stabilizing selection
B. disruptive selection
D. none of the above
3. How are the changes in Graph C different from those in Graphs A and B?
A. They will lead to larger beak size.
B. They will lead to the extinction of the population.
C. They will make the gene pool more stable.
D. They will lead to two different phenotypes.
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Use the table to answer questions 4–7.
Initial Population
Generation 10
Generation 20
Generation 30
90%
80%
70%
40%
20%
30%
60%
10%
4. What happened to the relative frequency of the allele for lighter fur color?
A. It increased.
C. It became extinct.
B. It decreased.
D. It did not change.
5. What is the percentage of mice with lighter fur color in Generation 20?
A. 40%
B. 60%
C. 70%
D. 80%
6. What can you infer from the data table about the mice in Generation 30?
A. Lighter mice are more likely to mate with darker mice.
B. Lighter mice are more likely to survive and reproduce.
C. Darker mice are more likely get sick and die.
D. Darker mice are more likely to survive and reproduce.
Short-Response Question
Answer the following question in two or three sentences.
7. Look at the table above. What trend does it show? What changes to the mice’s enviroment
might change that trend?
Sample answer: Right now, the trend is for the number of darker mice to increase in
each generation, while the number of lighter mice decreases. However, if the environment changes to make lighter fur color more adaptive, then the number of lighter
mice may increase over time while the number of darker mice may decrease.
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Classification
Unity and Diversity of Life
Q: What is the goal of biologists who classify living things?
Chapter Summary
The diagram below shows what you will read about in this chapter and how the chapter is
organized. Study the diagram. Then answer the questions that follow.
18.1 Finding Order
in Diversity
Assigning scientific names
Linnaean classification system
Evolutionary classification
18.2 Modern
Evolutionary
Classification
Cladograms
DNA in classification
18.3 Building the
Tree of Life
Changing ideas about kingdoms
The tree of all life
1. What do you think you will learn about in this chapter? Sample answer: I will learn how
living things are put into groups.
2. In which lesson do you expect to learn about Carolus Linnaeus and his system of naming
Lesson 1
and classifying organisms?
3. In which lesson will you learn the latest ideas about kingdoms?
Lesson 3
4. What do you think cladograms are? Sample answer: I think cladograms are diagrams
that show something related to modern evolutionary classification.
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18.1 Finding Order in Diversity
Lesson Objectives
Describe the goals of binomial nomenclature and systematics.
Identify the taxa in the classification system devised by Linnaeus.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Binomial
nomenclature
The two-word naming system in
which each organism is given a
genus name and species name
Bi- means “two,” and nom is similar to
name, so I can remember that binomial
nomenclature is a two-word naming system.
Class
A group of similar orders
“Kids prefer candy over fresh green
spinach.” C comes before O. A class is
made up of groups of orders.
Family
A group of similar genera
“Kids prefer candy over fresh green
spinach.” F comes before G. A family is
made up of groups of genera.
Genus
A group of similar species
“Kids prefer candy over fresh green
spinach.” G comes before S. A genus is
made up of groups of species.
Kingdom
The largest and most inclusive group
in the Linnaean classification system
“Kids prefer candy over fresh green
spinach.” Kingdom is the largest
Linnaean group.
Phylum
A group of similar classes
“Kids prefer candy over fresh green
spinach.” P comes before C. A phylum
is made up of groups of classes.
Systematics
The science of naming and
grouping organisms
Systematics is a system to organize
living things.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
Note: Students should highlight terms and definitions used throughout the chapter.
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BUILD Understanding
Preview Visuals Previewing visuals and taking notes about them can help you remember
what you read and review for tests. Visuals include photographs, charts, graphs, cladograms,
and diagrams. As you look at each visual, think about why it may be important to the lesson.
Look at the From Species to Kingdom diagram. In the chart below, write questions you have
about the diagram in the left column. As you read, write answers to your questions in the
right column. One has been done for you.
Questions
Answers
Why are all the groups, or levels, in the diagram
important?
The groups show how organisms are similar or
different from other organisms.
Sample questions: Why do the levels get
smaller as you move up? What features
do these animals have that place them
into different groups?
BUILD Connections
Levels in Your Life The pyramid below is similar to a pyramid used to show the Linnaean
classification system.
Follow the directions.
1. Think about the different levels of organization in your life—from you as an individual to
you as a resident of the world.
2. Fill in the rest of the pyramid with other “taxa.”
Sample answer:
Me
My family
My neighborhood
My city
My state
My country
The world
Answer the question.
3. How are the levels in your pyramid similar to the different levels of the Linnaean
classification system? Sample answer: Each layer of organization in my pyramid is
bigger than the one above it. My neighborhood is part of my city, just like a particular
genus is part of the family it belongs to.
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Linnaean Classification System
Linnaeus developed a system of classification to name and group organisms in a logical
manner. This made it easier to study the many forms of life.
In Linnaeus’s system, there are seven levels: kingdom, phylum, class, order, family, genus,
species. Look at the first letter in each word of the sentence “Kids prefer candy over fresh
green spinach.” This will help you to remember the names of the seven levels in the correct
order.
The diagram at the right shows how a grizzly bear
is classified in the Linnaean classification system.
Species
Follow the directions.
Ursus arctos
1. Fill in the names of the taxa. Use the
words from the box.
kingdom
class
species
phylum
order
genus
family
Genus
Ursus
2. Put an X on the highest, or most specific,
taxon that includes the grizzly bear and
the red fox.
Family
Ursidae
3. Circle the taxa that include reptiles.
Answer the questions.
4. Using binomial nomenclature, what is
Order
the scientific name of the grizzly bear?
Ursus arctos
Carnivora
X
5. To which phylum does the grizzly bear
belong?
Chordata
6. Name one other animal that belongs to
Class
the same class as the grizzly bear.
Mammalia
Accept any mammal.
7. What type of animals belong to the same
family as Ursus arctos?
bears
Phylum
Chordata
Kingdom
Animalia
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18.2 Modern Evolutionary Classification
Lesson Objectives
Explain the difference between evolutionary classification and Linnaean classification.
Describe how to make and interpret a cladogram.
Explain the use of DNA sequences in classification.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Clade
A group of species that includes
a single common ancestor and
all descendants of that ancestor
Clade starts with the same letters as clan, which
can be a group of people descended from the
same ancestor.
Cladogram
A picture that shows
evolutionary relationships
between groups of organisms
A cladogram shows how different clades
are related.
Derived
character
A trait that developed in the
most recent common ancestor
of a lineage and was passed
down to all its descendants
Derived means “come from.” A derived
characteristic is a trait that came from a
common ancestor.
Monophyletic
group
A group that includes all
species that are descended
from a common ancestor and
cannot include any species that
are not descended from that
ancestor
Mono means “one.” A monophyletic
group is a group of species that are
descended from one ancestor.
Phylogeny
(fy LAHJ uh
nee)
The study of how living and
extinct organisms are related
A phylum is a group of related organisms.
Phylogeny is the study of how organisms
are related.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the terms or the definition.
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BUILD Understanding
T-Chart A T-Chart is a way to organize information while you read. One way to make a
T-chart is to write the key questions in your textbook in the left column. As you read the
lesson, answer the questions in your own words. Write the answers in the chart.
Key Question
Answer
What is the goal
The goal is to group species into larger categories that reflect lines of
of evolutionary
evolutionary descent.
classification?
What is a cladogram?
A cladogram is a drawing that shows how evolutionary
lineages branched off from common ancestors.
How are DNA
DNA is used to see closely related species are. In general, the
sequences used in
more similar the DNA sequences are, the more recently the
classification?
species shared an ancestor.
Cladograms
Building Cladograms A cladogram shows evolutionary relationships between species.
You can think of a cladogram as a type of family tree.
Follow the directions to draw a cladogram below showing your family tree.
1. Choose an ancestor, such as a grandparent, on one side of your family. Draw the root of a
cladogram using this person as your common ancestor.
2. How many children did this person have? Draw a red branch on the cladogram to
represent each child.
3. How many children did each offspring of the common ancestor have? Off each branch,
draw a blue branch to represent each child.
4. Continue drawing branches until you have drawn branches for your generation. Use a
different color for each generation.
Make sure students’ drawings are cladograms that include correct placement and number of branches.
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Cladograms
Reading Cladograms A cladogram shows evolutionary relationships between species.
Follow the directions.
1. Use blue to color the organisms that have a molted external skeleton.
2. Use red to color the organisms without a molted external skeleton.
3. Circle the point on the cladogram that shows the most recent common ancestor of the
crab and the barnacle.
4. Draw an X at the point on the cladogram that shows the most recent common ancestor of
mollusks and crustaceans.
CLADOGRAM
Crustaceans
(blue)
Crab
(blue)
Mollusk
Barnacle
Limpet
(red)
Molted
external skeleton
Segmentation
Tiny free-swimming larva
Answer the questions. Circle the correct answers.
5. Which organism, or organisms, shows segmentation?
barnacle
limpet
6. What do all three organisms have in common?
tiny free-swimming larva
molted external skeleton
segmentation
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Inquiry Into Scientific Thinking
Constructing a Cladogram Cladograms organize living things by how closely related
they are. A cladogram includes common ancestors and all of their descendants.
1. Look at the table of plants and their traits below.
2. Write the plant names where they belong on the cladogram.
3. Write the derived characteristics next to the correct circles on the cladogram.
Plants
Derived Characteristics
Water-Conducting
Tissue
Seeds
Flowers
Cone-bearing plant
present
present
absent
Ferns
present
absent
absent
Mosses
absent
absent
absent
Flowering plants
present
present
present
Flowering
plants
Cone-bearing
plants
Ferns
Mosses
Flowers
Seeds
Water-conducting
tissue
Analyze and Conclude
1. What trait was present in the most organisms?
water-conducting tissue
flowers
2. Which trait was present in the fewest organisms?
3. Which plant lacks water-conducting tissue?
mosses
4. Which of the following pairs of plants are more closely related? Circle your answer.
mosses and flowering plants
cone-bearing and flowering plants
5. A plant called a horsetail has no seeds, but it does have water-conducting tissue. Where
would you place it on the cladogram above?
in the same area as ferns
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18.3 Building the Tree of Life
Lesson Objectives
Name the six kingdoms of life as they are currently identified.
Explain what the tree of life represents.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Archaea
(AHR kee)
Domain of unicellular
prokaryotic organisms that do
not have peptidoglycan in their
cell walls
The domain Archaea is made up of the
kingdom Archaebacteria.
Bacteria
Domain of unicellular
prokaryotic organisms that
have peptidoglycan in their cell
walls
I can remember that members of this
domain are eubacteria.
Domain
The most inclusive taxonomy
category
My “domain” contains all of my personal space. I
can remember that a domain contains all other
categories.
Eukarya
Domain that consists of all
organisms that have a nucleus
I know a eukaryote has a nucleus. All
members of the domain Eukarya have a
nucleus.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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BUILD Understanding
Concept Map A concept map can help you organize information and show how ideas are
connected. The concept maps below organize information about kingdoms and domains.
As you read Lesson 3, use the terms from the box to complete the concept maps. You may use
a term once or more than once.
Animalia
Fungi
six kingdoms
There were
Archaebacteria
Plantae
Monera
five
kingdoms
Eubacteria
Protista
three domains
called
Monera, Protista, Fungi,
Plantae, and Animalia.
Now there are
six kingdoms
called
Eubacteria, Archaebacteria,
Protista, Fungi, Plantae,
and Animalia.
There are
three domains
called
Bacteria, Archaea, and
Eukarya.
CHAPTER
Grin and Bear It Are brown bears and polar bears members of the same species?
What do you think? Write a hypothesis. Then, describe at least two ways you would
investigate the hypothesis.
Students’ answers should state whether or not they think polar bears and brown
bears are the same species. They should describe at least two ways to prove their
hypotheses, including looking at physical features, building a cladogram, studying
DNA, or studying breeding patterns.
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The Tree of All Life
All organisms belong to one of three domains. An organism is placed into a domain based on
its characteristics. A domain is the most inclusive taxonomic category. A single domain can
contain one or more kingdoms. The domain Eukarya is made up of four kingdoms: Animalia,
Fungi, Plantae, and Protista.
Follow the directions.
1. Write each of the following domain names in the correct place in the chart: Bacteria,
Archaea, Eukarya.
Three Domains
Domain
Organism Characteristics
Kingdoms Included
in Domain
Bacteria
Prokaryotes with cell walls
made up of peptidoglycan
Eubacteria
Eukarya
Eukaryotes
Protista, Fungi, Plantae, Animalia
Archaea
Prokaryotes whose cell walls do
not contain peptidoglycan
Archaebacteria
2. Write each of the following kingdom names in the correct place in the chart: Animalia,
Fungi, Plantae, Protista.
Kingdom
Cell Structures
Number of Cells
Mode of Nutrition
Cell walls of cellulose in some;
some have chloroplasts
Most unicellular; some
multicellular
Autotroph or
heterotroph
Cell walls of chitin
Most multicellular;
some unicellular
Heterotroph
Plantae
Cell walls of cellulose;
chloroplasts
Multicellular
Autotroph
Animalia
No cell walls or chloroplasts
Multicellular
Heterotroph
Protista
Fungi
Answer the questions.
Protista and Plantae
3. Which kingdoms contain autotrophs?
4. To which kingdom do grizzly bears belong?
Animalia
5. In which domain would you classify a unicellular heterotroph?
Fungi
6. What do fungi and animals have in common? Both fungi and animals are heterotrophs.
7. What do some protists and plants have in common? They both have cell walls of
cellulose. Some protists have chloroplasts, as do plants.
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Chapter Review
Use the clues and words to help you write the vocabulary terms from the chapter in
the blanks.
phylum
1.
A kingdom
2.
A cladogram
3.
A phylum
kingdom
cladogram
is the largest taxon in the Linnaean classification system.
is used to show how different species are related to a common ancestor.
is made up of similar classes.
Answer the following questions.
4. Binomial nomenclature was developed by
Linnaeus
.
5. In binomial nomenclature, part of an organism’s scientific name is
A. the name of its phylum.
C. the name of its family.
B. the name of its order.
D. the name of its genus.
6. Draw and label a pyramid to show the order of the different classification groups. Use
these words: species, domain, phylum, order, class, kingdom, family, genus.
Students’ pyramids should list groups in this order, from top to bottom: species, genus,
family, order, class, phylum, kingdom, domain.
7. According to the cladogram below, which two clades include animals that have specialized
Clade Carnivora and Clade Felidae
shearing teeth?
Clade Tetrapoda
Amphibians
Clade Amniota
Clade Mammalia
Reptiles
Marsupials
Hair
Four
limbs
Clade Carnivora
Clade Felidae
Dogs and relatives
Specialized
shearing teeth
Cats
Retractable
claws
Amniotic egg
(egg with
membranes)
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Taking a Standardized Test
Test-Taking Tip: Read the Question in Parts
When a test question is long, read the question in parts. Think about what each part means
before you read the next one.
Step 1 Look at the question below. Break it into parts. This question can be broken into
three parts. Part 1 tells how coyotes and lions are similar. Part 2 tells how they are different.
Part 3 is the question.
Coyotes and lions both have hair, four limbs, and specialized shearing teeth. Lions have
retractable claws. Coyotes do not. Based on this information, which of the following
statements is true? Use the cladogram on the previous page to help you.
A. Coyotes and lions both belong to clade Carnivora.
B. Coyotes and lions do not have a recent common ancestor.
C. Coyotes and lions are both dogs.
D. Coyotes and lions are both cats.
Step 2 Read each part carefully. Make sure you understand the information in each part
before you read the next part. If you do not understand a part, reread it. If you still do not
understand part of the question, read the question as a whole to see if there are any other
clues to help you.
Step 3 Once you have read all the parts, use the information to answer the question. This
question asks you to use the information in Parts 1 and 2 to determine which statement is
true. Coyotes and lions have many similarities. However, they have an important difference.
Step 4 Cross out the answers you know are wrong. Choose the correct answer. According
to the cladogram, coyotes and lions cannot both be cats, since cats have retractable claws, so
cross out D. Dogs do not have retractable claws, so cross out C. Because they share several
derived characteristics, coyotes and lions share a common ancestor. Therefore, B is incorrect.
The traits they share are all characterisitics of clade Carnivora. This means the correct answer
is A.
Self-Test
Practice what you have learned by answering the following questions. If the question is long,
break it into parts. Read each part carefully. Then, circle the correct answer.
1. Both snakes and squirrels are animals. Mammalia is a class of animals that are covered
with hair. Based on this information, which classification group includes both snakes and
squirrels?
A. species
B. order
C. class
D. kingdom
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2. All eukaryotes have mitochondria. This means that for eukaryotes, mitochondria can be
considered a(n)
A. derived characteristic.
C. mutation.
B. inherited trait.
D. none of the above
3. Eubacteria are prokaryotes that can be autotrophic or heterotrophic. Protists are
eukaryotes that can be autotrophic or heterotrophic. Based on this information, which of
the following statements is true?
A. Eubacteria and protists make up the same domain.
B. Eubacteria and protists make up the same kingdom.
C. Eubacteria and protists have a common ancestor.
D. Eubacteria and protists are most likely not closely related.
4. Linnaeus is considered the father of modern taxonomy. For the most part, we still classify
organisms using the Linnaean system created in the eighteenth century. Which of the
following is NOT part of the Linnaean system?
A. binomial nomenclature
C. kingdoms
B. domains
D. species
5. Both camels and giraffes belong to the order Artiodactyla. This means they must belong to
the same
A. class
C. kingdom
B. family
D. both A and C
6. On a cladogram, the branches for kingdom Protista are not together in one area. Some
branches are located near fungi. Some are near plants. Others are near animals. What does
this mean about protists?
A. Protists have nothing in common.
B. Protists are more closely related to Achaebacteria.
C. Protists do not form a single clade.
D. Protists can be classified in many kingdoms.
Short-Response Question
Answer the following question in two or three sentences.
8. Why might the classification system we use today change? How can it change?
Sample answer: As more tools and information become available, we learn more
about organisms, their DNA, and their evolutionary history. We might discover that
an animal we thought was part of one species is actually a separate species. We
might also discover that two organisms that we thought were different species are
really the same.
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History of Life
Evolution
Q: How do fossils help biologists understand the history of life on Earth?
Chapter Summary
The diagram below shows what you will read about in this chapter and how the chapter is
organized. Study the diagram. Then answer the questions that follow.
Fossils and ancient life
19.1 The Fossil
Record
Dating Earth’s history
Geologic time scale
Life on a changing planet
Speciation and extinction
19.2 Patterns and
Processes of
Evolution
Rate of evolution
Adaptive radiation and convergent evolution
Coevolution
19.3 Earth’s Early
History
The mysteries of life’s origins
Origin of eukaryotic cells
Sexual reproduction and multicellularity
1. What are the main topics of this chapter? the fossil record, evolution, and Earth’s early
history
2. In which lesson do you expect to learn how scientists date events in Earth’s early history?
Lesson 1
3. Why do you think extinction is included in a lesson about evolution? Sample answer: Not
all species survive. Some become extinct during the evolutionary process.
4. Name two processes of evolution you will learn more about. Accept any two: speciation,
extinction, adaptive radiation, convergent evolution, coevolution.
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19.1 The Fossil Record
Lesson Objectives
Explain what information fossils can reveal about ancient life.
Differentiate between relative dating and radiometric dating.
Identify the divisions of the geological time scale.
Describe how environmental processes and living things have shaped life on Earth.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Era
A unit of time by which eons are
divided on the geologic time scale
I know that era refers to time. I can
remember that eons are divided into eras.
Extinct
A species that has died out
Half-life
The amount of time it takes for half of
the radioactive atoms in a sample to
decay
A half-life is the time it takes half of
the radioactive atoms in a sample to
decay.
Index fossil
A fossil that is used to determine
the relative ages of rock layers and
fossils
An index puts things in order. An
index fossil is a fossil that is used to
place rock layers and fossils in order
by age.
Paleontologist
A scientist who studies fossils to learn
more about ancient life
Paleo- means “old.” A paleontologist studies fossils, which are old.
Radiometric
dating
Method of determining the age of a
rock sample based on its remaining
radioactive atoms
Radiometric dating uses
radioactive isotopes to determine
how old something is in years.
Relative dating
Method of comparing the ages of
fossils and rock layers
Relative means “compared to.”
Relative dating must involve
comparisons of age.
An extinct species no longer exists.
Note: Students should highlight terms and definitions used throughout the chapter.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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BUILD Understanding
Main Idea and Details Chart One way to take notes is to make a main idea and details
chart. In the chart below, the main ideas are the key questions from Lesson 1, and have been
filled in for you. In the right column, write details that support the main idea.
Main Idea
Details
What do fossils reveal about ancient life?
How do we date events in earth’s history?
Fossils tell us about species that no longer
exist. Fossils show the structure of ancient
organisms, their environment, and the way
they lived.
Scientists use a combination of relative dating
and absolute dating.
How was the geologic time scale
established, and what are its major
divisions?
The geologic time scale is based on relative
and radiometric dating. It is divided into eons,
eras, and periods.
How have our planet’s environment and
living things affected each other to shape
the history of life on Earth?
Life on Earth has been shaped by physical forces
like plate tectonics and biological forces like
photosynthesis.
BUILD Connections
Life As a Clock An analogy takes two things that seem to be different and shows how they
can be similar.
1. How does the analogy of the clock help you understand the
.
.M
3
evolution of life on Earth? Sample answer: It helps me under-
A
stand how relatively young humans are and how there was a
6 A.M.
6 P.M.
.
9
.M
P
MIDNIGHT
24–hour clock
period of time when there was no life on Earth. It makes the
.
3
concept of billions of years easier to imagine.
.M
P.
M
.
9
NOON
A
2. Find a partner. Using the analogy, explain to your partner how
life on Earth evolved over billions of years.
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Dating Earth’s History
Relative Dating If undisturbed, the oldest layers of sedimentary rocks, and the fossils they
contain, lie beneath younger layers in the order in which they formed.
Follow the directions.
1. Number the rock layers in the order that they formed. The first one has been done for you.
6
5
4
3
2
1
2. Look at the rock layers to number the fossils in order from oldest to most recent. The
oldest fossil is labeled 1.
1
2
5
3
6
4
Answer the questions.
3. Suppose that you found a fossil of the same species as fossil 1 in a rock layer in another
location. What could you conclude about that rock layer?
A. It was formed before layer 1.
B. It was formed after layer 1.
C. It was formed at about the same time as layer 1.
D. None of the above
4. What is a weakness of relative dating? It cannot tell the absolute age of a fossil or rock
layer.
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Geologic Time Scale
Scientists have created a time line of Earth’s history. It is called the geologic time scale.
The three most important divisions on the geologic time scale are eons, eras, and periods.
Unlike time lines you have used in history class, the divisions on the geologic time scale are
of unequal length. For example, the Cambrian Period was 54 million years long, while the
Cretaceous Period was 80 million years long.
Follow the directions to make a time line of the geologic time scale.
1. Use the information in the table to divide the time line at right into periods.
2. Label each period.
4. Color the Mesozoic Era yellow.
Neogene
5. Color the Paleozoic Era blue.
Paleogene
50
(red)
Time (millions
of years ago)
Quaternary
Present
3. Color the Cenozoic Era red.
6. Color the Precambrian Time orange.
100
Period
Paleozoic
Phanerozoic
Mesozoic
Cenozoic
Quaternary
Precambrian
Time
150
Time (millions
of years ago)
Jurassic
200
1.8–present
Triassic
Neogene
23–1.8
Paleogene
65.5–23
Cretaceous
146–65.5
Jurassic
200–146
Triassic
251–200
Permian
299–251
Devonian
Carboniferous
359–299
Silurian
Devonian
416–359
Silurian
444–416
Ordovician
488–444
Cambrian
542–488
250
Permian
300
Carboniferous
350
400
(blue)
Era
450
Ordovician
500
Cambrian
550
Proterozoic
2500–542
Archean
4000–2500
Hadean
About 4600–4000
600
(orange)
Eon
(yellow)
Cretaceous
Geologic Time Scale
650
Answer the questions.
1. Name the periods that make up the Cenozoic Era. Quaternary, Neogene, and Paleogene
2. Which period came first, the Ordovician or the Carboniferous?
3. Which period began 200 million years ago?
Ordovician
Jurassic
4. Which era in the phanerozoic lasted the longest? How long did it last? the Paleozoic Era;
291 million years
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Inquiry Into Scientific Thinking
Modeling Half-Life For your model of half-life, you used 100 paper squares. What do you
think would happen if you used 200 squares?
Predict what will happen when you try the same activity using 200 squares.
Students may suggest that it will take longer to get to
If I use 200 squares, I predict that less than 5 squares.
Follow the directions to repeat the activity using 200 squares.
1. Use the 100 squares from the Modeling Half-Life activity. Cut out 100 additional squares.
2. Make an X on one side of each square.
3. Place all 200 squares in a cup. Mix. Spill out the squares.
4. Remove the squares that have an X showing.
5. Count the number of squares left. These are the ones that landed X down. Record this
number in the chart below.
6. Place the remaining squares in the cup.
7. Repeat the process of spilling and removing squares until fewer than 5 squares remain.
Spill Number
Number of Squares Left
Spill Number
1
7
2
8
3
9
4
10
5
11
6
12
Number of Squares Left
Analyze and Conclude
1. If each spill is one year, what is the half-life of the 200-square sample? Answers will vary.
2. How did the half-life of the 200-square sample compare to the half-life of the 100-square
sample?
Answers will vary. Most students will report that they were very similar.
3. Do you think the amount of an element affects the element’s half-life? Why? Sample
answer: No, I think the half-life is the same. When you have more atoms of an element, more will decay. But the time it takes for half to decay is the same.
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19.2 Patterns and Processes of Evolution
Lesson Objectives
Identify the processes that influence survival or extinction of a species or clade.
Contrast gradualism and punctuated equilibrium.
Name two important patterns in macroevolution.
Explain the evolutionary characteristics of coevolving organisms.
BUILD Vocabulary
The chart below shows key terms from the lesson with their definitions. Complete the chart
by writing a strategy to help you remember the meaning of each term. One has been done
for you.
Term
Definition
How I’m Going to Remember
the Meaning
Adaptive radiation
The process by which a species has
evolved over a relatively short time into
several forms that live in different ways
New species form when old
species adapt to live in new
ways.
Coevolution
The process in which two species
evolve in response to changes in each
other
The prefix co- is used to describe
things that happen together.
Coevolution is two species evolving
together.
Convergent
evolution
The process in which unrelated
organisms evolve into forms that
resemble one another
Gradualism
A pattern of evolution that is slow and
steady
Gradual means slow and steady,
so gradualism is a process
of evolution that is slow and
steady.
Macroevolutionary
patterns
Large changes made by the process of
evolution over a long period of time,
usually in clades larger than a single
species
The prefix macro- means
“large,” as in a large period of
time and across a large number
of organisms.
Mass extinction
Term used to describe when many
species become extinct at the same
time
Punctuated
equilibrium
A pattern of evolution in which long
stable periods are interrupted by short
periods of great change
A mass is a large group. In a
mass extinction, a large group
of species become extinct at the
same time.
Equilibrium means “balanced.”
Punctuated equilibrium is
when a period of balance is
interrupted by a period of
change.
Convergent means “to come
together from different points.”
LLesson 19
19.2
2•W
Workbook
kb k B • C
Copyright
i h ©b
by PPearson Ed
Education,
i
IInc., or iits affi
ffililiates. All rights
i h reserved.
d
287
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BUILD Understanding
Concept Map A concept map can help you organize information and show how ideas
are connected.
As you read Lesson 2, complete the concept map below.
Sample answers:
Macroevolutionary
patterns
Punctuated
Equilibrium and
Grandualism
Adaptive
Radiation
refer to
the changes made by evolution over long periods of
time and across a wide number of organisms
include
speciation and extinction
both describe
rates of evolution
is
process by which a single species evolves over
a short time into several different forms that
live in different ways
a part of a population moves to a
new place or when other organisms
become extinct
can occur when
Convergent
Evolution
Coevolution
is
the process by which unrelated organisms
evolve into forms that resemble each other
occurs when
the organisms face similar
environmental challenges
when two species evolve in response
to changes in each other
is
occurs when
the relationship between two organisms
is so specific that neither can live
without the other
flowers and pollinators, plants and
herbivorous insects
examples are
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Rate of Evolution
Evolution does not always occur at the same rate. It can happen slowly over a long period of
time. It can also happen quickly. Gradualism describes evolution that occurs slowly over time.
Punctuated equilibrium describes a pattern of long periods of stability interrupted by shorter
periods of rapid evolution.
Follow the directions.
1. Label the diagram below that shows gradualism.
2. Label the diagram below that shows punctuated equilibrium.
Gradualism
Time
Punctuated Equilibrium
Ancestor
Time
Ancestor
Genetic Change
Genetic Change
Answer the questions.
3. Look at the diagram you labeled gradualism. How do you know that this shows evolution
occurring over a long period of time? The evolution occurs slowly and in many small
steps. The original species changes very slowly.
4. Look at the diagram you labeled punctuated equilibrium. How do you know that this
diagram shows evolution occurring rapidly? There are not that many changes shown;
the species changes very quickly.
5. Give one reason a species could evolve quickly in a short time. Accept any one of the
following answers: A small population becomes isolated from a larger population, so
genetic changes spread more quickly over a few individuals. A small group of organisms migrates to a new environment. Mass extinctions open up ecological niches.
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Adaptive Radiation and Convergent Evolution
Adaptive Radiation One macroevolutionary process is adaptive radiation. In adaptive
radiation, a single species or small group of species evolves over a short time into many forms
that live in different ways. Adaptive radiation often happens when there is a dramatic change
in a species’ environment. The evolutionary changes that occur allow the organism to survive.
The diagram below shows part of the adaptive radiation of mammals.
Look closely at the diagram. Pay close attention to the relationships among mammal groups.
Artiodactyls
Cetaceans
Perissodactyls
Tubulidentates
Hyracoids
Sirenians
Proboscideans
Mammal ancestor
Answer the questions.
1. Which group is most closely related to the sirenians?
proboscideans
2. Which group is most closely related to artiodactyls?
cetaceans
3. Which group(s) had a mammalian ancestor?
A. Artiodactyls
B. Cetaceans
C. Hyracoids
D. All of the above
4. Adaptive radiation is the process by which
A. species evolve together.
B. unrelated species evolve to look alike.
C. one species evolves into many forms that live in different ways.
D. one species evolves into a single new species.
5. Which two animals are believed to be more closely related?
sirenians and hyracoids
sirenians and tubulidentates
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19.3 Earth’s Early History
Lesson Objectives
Identify some of the hypotheses about early Earth and the origin of life.
Explain the endosymbiotic theory.
Explain the significance of sexual reproduction in evolution.
BUILD Vocabulary
A. The chart below shows the key term in this lesson with its definition. Complete the chart
by writing a strategy to help you remember the meaning of the term.
Word
Definition
How I’m Going to Remember
the Meaning
Endosymbiotic
(en doh sim by
AHT ik) theory
A theory that says that
eukaryotic cells formed from
a symbiosis among several
different prokaryotic organisms
The prefix endo- means “within,” so I can
remember that eukaryotic cells formed
from prokaryotic cells that were in a symbiotic relationship.
B. As you work through this lesson, you may find this term in the activities. When you need
to write the key term or its definition, highlight the term or the definition.
BUILD Understanding
Flowchart A flowchart is a way to show a sequence of events. You can make a flowchart by
writing the steps in a series of connected boxes.
As you read Lesson 3, complete the flowchart to show the major steps from the origin of
Earth to the evolution of eukaryotic cells.
Earth forms.
Oceans form.
Organic
molecules
form.
Free oxygen
is produced.
Prokaryotes
form.
Microspheres
form.
RNA
and DNA
evolve.
Eukaryotes
evolve from
prokaryotes.
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The Mysteries of Life’s Origins
Scientists have as many questions as answers about the origins of life on Earth. The study of
life’s origins is a branch of scientific research that is always changing. Scientists do know that
early Earth was a very different place than today’s Earth.
Follow the directions.
1. Fill in the chart with information about early Earth and today’s Earth. Use terms from
the box.
brown oceans
blue skies
pinkish-orange skies
blue oceans
no life
many different life forms
about 20% oxygen
little to no oxygen
Early Earth
Today’s Earth
Oceans
brown oceans
blue oceans
Skies
pinkish-orange skies
blue skies
Atmosphere
little to no oxygen
about 20% oxygen
Life
no life
many different life forms
Each of the following statements is false. Rewrite the statements to make them true.
2. Oceans on early Earth were blue because they contained lots of dissolved iron. Oceans on
early Earth were brown because they contained lots of dissolved iron.
3. The atmosphere on early Earth could support human life because there was no oxygen.
The atmosphere on early Earth could not support human life because there was no
oxygen.
4. For millions of years, asteroids shook Earth’s crust. For millions of years, violent volcanic
activity shook Earth’s crust.
5. Microspheres evolved from living cells.
Living cells evolved from microspheres.
6. The first cells on Earth were eukaryotic.
The first cells on Earth were prokaryotic.
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The Mysteries of Life’s Origins
Production of Free Oxygen Early Earth’s atmosphere was mostly a mixture of carbon
dioxide, water vapor, and nitrogen. There was little to no oxygen. Life as we know it today
developed because of the production of free oxygen.
A cause-and-effect chart is similar to a flowchart. It shows what the impact of a certain
event is. The event is the cause. The impact of the event is the effect. Many causes can also be
effects.
Follow the directions.
1. Complete the cause-and-effect chart below. Use the sentences in the box.
Organisms that used oxygen for respiration evolved.
The first cells became extinct.
The oceans changed color from brown to blue.
The ozone layer formed and skies turned blue.
The iron oxide sank to the ocean floor.
Cause: Photosynthetic bacteria began
producing oxygen.
Cause/Effect:
Oxygen combined with iron in the oceans
to form iron oxide.
Cause/Effect:
Oxygen accumulated in the atmoshpere.
Cause/Effect:
Cause/Effect:
The iron oxide sank to the ocean
floor.
The ozone layer formed and the
skies turned blue.
Effect:
Cause/Effect:
The oceans changed color from
brown to blue.
The first cells became extinct.
Effect:
Organisms that used oxygen for
respiration evolved.
Answer the questions.
2. What life process put oxygen into the atmosphere?
photosynthesis
3. Why do you think the first cells became extinct? They had evolved without oxygen, so to
them, oxygen was a deadly gas.
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Origin of Eukaryotic Cells
Endosymbiotic Theory The endosymbiotic theory explains the evolution of eukaryotic
cells. According to the theory, ancient prokaryotes developed a symbiotic relationship with
smaller prokaryotes that lived inside them. Some of these smaller prokaryotes could use
oxygen to make ATP. These aerobic prokaryotes evolved into mitochondria. Others could
perform photosynthesis. These evolved into chloroplasts. The diagram below shows the
stages in the endosymbiotic theory.
Follow the directions to finish the diagram.
1. Draw the final step in the endosymbiotic theory. Your drawing should show a primitive
eukaryotic cell that performed photosynthesis.
2. Label the chloroplast in your drawing.
Ancient Anaerobic
Prokaryote
Ancient Aerobic
Prokaryote
Nuclear envelope
evolving
Mitochondrion
Primitive Aerobic
Eukaryote
Ancient Photosynthetic
Prokaryote
Animals, fungi, and
non-plantlike protists
chloroplast
Plants and
plantlike protists
Primitive Photosynthetic Eukaryote
Answer the questions.
3. Animals evolved from primitive eukaryotic cells with which structure?
chloroplast
mitochondria
nucleus
4. What evidence shows that bacteria and organelles of living cells share a common ancestry?
Mitochondria and chloroplasts share many features of bacteria.
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CHAPTER
Murder in the Permian More than 250 million years ago, during the Permian
Period, life on Earth was almost completely wiped out. Scientists think it could have been
a combination of many factors including a volcanic eruption that caused global climate
changes and the impact of a giant asteroid.
Draw a picture to show what scientists think happened. Give your drawing the title
“Extinction in the Permian.” Write a caption for your drawing to explain how scientists
think each factor could have contributed to the mass extinction.
Students’ drawings should show both
volcanic activity and a large asteroid
hitting Earth. Captions should explain
how each could have contributed to the
mass extinction.
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Chapter Review
Draw lines to match the vocabulary terms from the chapter with their definitions.
pattern in which evolution occurs slowly and
steadily over time
someone who studies fossils and ancient life
the theory that eukaryotic cells developed
from prokaryotic cells in a symbiotic
relationship
term used to describe a species that has
died out
a pattern of evolution in which two species
evolve in response to changes in each other
1. extinct
2. paleontologist
3. gradualism
4. coevolution
5. endosymbiotic theory
Answer the questions.
6. Scientists learn more about ancient life from the
fossil record
.
7. What do scientists use to determine the age of fossils?
A. relative dating
C. geologic time scale
B. radiometric dating
D. both A and B
8. Which of the following organelles is not a part of the endosymbiotic theory?
chloroplast
mitochondrion
vacuole
9. Make a flowchart to show the steps Miller and Urey used to show how the first organic
molecules were formed. Use the sentences from the box.
Cold water cools the chamber, causing droplets to form.
Circulating gases are jolted with electricity.
Water is heated, and water vapor forms.
A mixture of gases found in early Earth’s atmosphere is added to the water vapor.
Liquid containing amino acids is collected.
Water is
heated, and
water vapor
forms.
A mixture of
gases found
in early
Earth‘s
atmosphere
is added to
the water
vapor.
Circulating
gases are
jolted with
electricity.
Cold water
cools the
chamber,
causing
droplets to
form.
Liquid
containing
amino acids
is collected.
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Taking a Standardized Test
Test-Taking Tip: All of the Above
Sometimes more than one answer can be correct. When “all of above” is a choice, choose it if
you know all the answer choices are correct.
Read the following question and answer choices.
Which is an environmental process that has shaped the history of life on Earth?
A. plate tectonics
B. astronomical events
C. global climate changes
D. all of the above
Step 1 Read the question and answer choices carefully. Be sure you understand the
question.
Step 2 Ask yourself if every choice would correctly answer the question. As you read
each answer choice, ask yourself if it correctly answers the question. Remember, if you choose
“all of the above,” every answer choice must be correct. In the example above, you could ask
yourself, “Is plate tectonics an environmental process that shaped the history of Earth? Yes, it
is.” Make a mark next to the answer choices that correctly answer the question.
Step 3 Choose the correct answer. Look at the marks you made as you were answering the
questions. Did you put a mark next to each answer choice? If the answer is yes, then you can
circle D. In this case, the correct answer is “all of the above.”
Self-Test
Practice what you have learned by answering the following questions. Circle the correct
answer. Remember to choose “all of the above” only when all of the answer choices
are correct.
1. Which of the following is a possible cause of a mass extinction?
A. An asteroid hits Earth.
B. A volcano erupts.
C. Oxygen levels in the ocean suddenly drop.
D. all of the above
2. Which of the following is true of gradualism?
A. It takes place over a short period of time.
B. It takes place over a long period of time.
C. It takes place after a period of equilibrium.
D. all of the above
3. Which of the following is a division on the geologic time scale?
A. eon
B. era
C. period
D. all of the above
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Use the geologic time scale to answer Questions 4 and 5.
Geologic Time Scale
Era
Paleozoic
Phanerozoic
Mesozoic
Cenozoic
Eon
Precambrian
Time
Time (millions
of years ago)
Period
Quaternary
1.8–present
Neogene
23–1.8
Paleogene
65.5–23
Cretaceous
146–65.5
Jurassic
200–146
Triassic
251–200
Permian
299–251
Carboniferous
359–299
Devonian
416–359
Silurian
444–416
Ordovician
488–444
Cambrian
542–488
Proterozoic
2500–542
Archean
4000–2500
Hadean
About 4600–4000
4. Which of the following is a period in the Cenozoic Era?
A. Neogene
C. Quaternary
B. Paleogene
D. all of the above
5. The Mesozoic Era includes the
A. Silurian Period.
C. Jurassic Period.
B. Permian Period.
D. all of the above
6. Which relationship is an example of coevolution?
A. flowers and pollinators
C. humans and dogs
B. mammals and dinosaurs
D. all of the above
Short-Response Question
Answer the following question in two or three sentences.
7. Are the similar body shapes of water animals like sharks and dolphins an example of
convergent evolution or adaptive radiation? Explain your answer.
Sample answer: It is an example of convergent evolution. Dolphins and sharks are
not closely related organisms. They have similar body shapes because both animals
live in the ocean and experience similar selection pressures. Their similarities are the
result of natural selection molding different structures to perform similar functions.
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Viruses and Prokaryotes
Cellular Basis of Life
Q: Are all microbes that make us sick made of living cells?
Chapter Summary
The diagram below shows what you will read about in this chapter and how the chapter is
organized. Study the diagram. Then answer the questions that follow.
20.1 Viruses
The discovery of viruses
Viral infections
Classifying prokaryotes
20.2 Prokaryotes
Structure and function
The importance of prokaryotes
Bacterial diseases
20.3 Diseases
Caused by
Bacteria and
Viruses
Viral diseases
Emerging diseases
1. What do you think you will learn about in this chapter? viruses, prokaryotes, and the
diseases they cause
2. In which lesson do you expect to learn more about how viruses cause disease? Lesson 3
3. What do you think is meant by “emerging diseases”? Sample answer: diseases that are new
4. Predict two things you will learn about in Lesson 3. Sample answer: bacterial diseases
and viral diseases
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20.1 Viruses
Lesson Objectives
Explain how viruses reproduce.
Explain how viruses cause infection.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the
chart by writing a strategy to help you remember the meaning of each term. One has been
done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Bacteriophage
A virus that infects bacteria
Phage sounds like “fight”;
bacteriophages fight bacteria.
Capsid
The protein coat surrounding a virus
A capsid is like a cap that
covers your head.
Lysogenic
infection
Infection in which a virus inserts its nucleic
acid into the DNA of the host cell and is
duplicated with the cell’s DNA
Think lyso = lie-so. The virus
lies to the cell so it can
regenerate itself for
generations.
Lytic infection
An infection in which a virus enters a
bacterial cell, makes copies of itself, and
causes the cell to burst, or lyse
A lytic infection is like a
ticking time bomb that causes
the cell to “blow up.”
Prophage
Bacteriophage DNA that is inserted into
the bacterial host’s DNA
The prophage virus is a real
pro ; it gets into the cell and
takes over everything.
Retrovirus
A virus that contains RNA as its genetic
material and that copies its genetic
material from RNA to DNA
Retrovirus starts with R. A
retrovirus copies its genetic
material from RNA to DNA.
Virus
A nonliving particle made of proteins,
nucleic acids, and sometimes lipids, that
can only reproduce by infecting cells
Computer viruses can infect
your computer.
Note: Students should highlight terms and definitions used throughout the chapter.
B. As you work through this lesson, you may find these terms in the activities. When you need
to write a key term or a definition, highlight the term or the definition.
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The Discovery of Viruses
Viruses are particles made up of protein, genetic material, and sometimes lipids. The genetic
material in a virus can be RNA or DNA. The protein coat that surrounds the genetic material
is called the capsid.
Follow the directions.
1. Circle the genetic material in each virus.
2. Color the protein parts of each virus red.
T4 Bacteriophage
Tobacco
Mosaic
Virus
Tobacco Mosaic
Virus
Capsid
DNA
Head
(red)
Influenza Virus
(red)
Capsid
(red)
(red)
Answer the questions.
1. Where is the genetic material in a T4 bacteriophage located? The genetic material is
located in the head.
2. In general, is the genetic material in a virus inside or outside the protein parts?
inside
3. Why do you think the word virus, based on the Latin word for poison, was used for these
structures?
Sample answer: because many viruses cause disease
BUILD Understanding
Venn Diagram A Venn diagram is made up of overlapping circles. It is a useful tool for
comparing two or even three topics.
As you read Lesson 1, complete the Venn diagram below with information about viruses and
cells.
Viruses
Cells
• nonliving
Both
• cannot grow
•
can
reproduce
• does not obtain
•
change
over
energy
time
• can only reproduce
•
have
genetic
in host cell
code
•
•
•
•
living
can grow
can obtain energy
can reproduce
independently
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Viral Infections
A bacteriophage is a virus that can infect bacteria. A lytic infection is one kind of viral
infection. It results in lysis, or bursting of the host cell.
A lysogenic infection is another kind of viral infection. It occurs when viral DNA inserts
itself into the DNA of the host cell. The viral DNA is replicated along with the host cell DNA.
Eventually, the viral DNA separates from the host DNA. It then directs the construction of
new virus particles.
The diagram below compares lytic and lysogenic infections.
Use the sentences to complete the diagram.
The proteins and nucleic acids assemble into new viruses.
Viral genes are transcribed by the host cell.
The virus injects DNA into a bacterium.
The prophage may replicate with the bacterium for many generations.
Prophage
LYSOGENIC INFECTION
The viral DNA inserts
itself into the bacterial
chromosome, where it
is called a prophage.
The virus injects DNA
into a bacterium.
LYTIC INFECTION
Viral genes are
transcribed
by the host cell.
Viral enzymes lyse
the bacterium’s cell
wall. The new viruses
escape and infect
other bacterial cells.
The prophage may
replicate with the
bacterium for many
generations.
The prophage can
exit the bacterial
chromosome and
enter a lytic cycle.
The bacterium makes
new viral proteins and
nucleic acids.
The proteins
and nucleic acids
assemble into new viruses.
Answer the questions.
1. Which type of viral infection includes the formation of a prophage? a lysogenic infection
2. What happens after viral enzymes lyse the bacterium’s cell wall? The new viruses can
infect other bacterial cells.
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Viral Infections
Lytic Infections In a lytic infection, a virus enters a cell. It then copies itself and causes the
cell to burst. Lysing is another word for this type of cellular destruction.
The flowchart below summarizes what happens in a lytic infection.
Follow the directions.
1. Use the following terms to complete the flowchart.
bacterium
viral proteins
virus
virus
The bacterium
New viruses are
enters or injects
then makes
assembled and
its DNA into a
viral proteins
burst out of the
bacterium.
and DNA.
A
bacterium .
Answer the questions.
2. What is one result of a lytic infection? Circle the correct answer.
destruction of the virus
destruction of the host
3. What happens to the viruses after they lyse the cell wall?They infect other cells.
BUILD Connections
How a Lytic Virus Is Like an Outlaw An analogy compares two things that are
different and shows how they can be similar.
1. How does the analogy of the lytic virus to an outlaw help you
understand lytic viruses?
Sample answer: It helps me understand that a lytic virus
breaks in and takes over the host cell’s DNA. The virus then
uses the host cell to make viral DNA and viral proteins. The
host cell bursts, releasing hundreds of virus particles.
2. Find a partner. Using the analogy, explain how a lysogenic
infection is also like an outlaw.
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20.2 Prokaryotes
Lesson Objectives
Explain how the two groups of prokaryotes differ.
Describe how prokaryotes vary in structure and function.
Explain the role of bacteria in the living world.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the chart by
writing a strategy to help you remember the meaning of each term. One has been done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Bacillus
A rod-shaped prokaryote
Rods look like bars, and both bar and
bacillus start with the letter B.
Binary fission
A type of asexual reproduction
in which a prokaryote replicates
its DNA and divides into two
identical halves
Fission means to “split apart.” Bimeans “two.”
Coccus
A sphere-shaped prokaryote
Coccus and circle both start with C.
A circle is similar to a sphere.
Conjugation
The process by which prokaryotes
exchange genetic material
I can remember that in conjunction two
prokaryotes are combined to exchange DNA.
Endospore
A thick internal wall that encloses
the DNA and part of the
cytoplasm in a prokaryote
For endo- think indoors. An endospore
encloses DNA, keeping it away from the
rest of the cell.
Prokaryote
A unicellular organism that lacks
a nucleus
The prefix pro- rhymes with no, and the
root karyo means “nucleus”; no nucleus.
Spirillum
A spiral- or corkscrew-shaped
prokaryote
A spirillum is shaped like a spiral.
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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Classifying Prokaryotes
A prokaryote is a unicellular organism that lacks a nucleus. Prokaryotes are classified into two
groups. Most prokaryotes have a cell wall, a cell membrane, and cytoplasm. The bacterium
below is one example of a prokaryote.
Follow the directions.
1. Color the ribosomes yellow.
2. Color the cell membrane blue.
3. Color the flagellum red.
4. Color the pili orange.
5. Color the DNA green.
(blue)
(yellow)
(green)
(orange)
(red)
Answer the questions.
6. What does the bacterium use to move? Circle the correct answer.
ribosome
flagellum
peptidoglycan
7. Circle the correct answer. Which structure is closest to the environment of the bacterial cell?
outer membrane
cell membrane
cell wall
8. What is the function of the cell wall? It protects the bacterium from injury and
determines its shape.
BUILD Understanding
Previewing Visuals The visuals in a lesson can provide useful information. Visuals
include photographs, maps, charts, graphs, and timelines. Preview the Prokaryotic Shapes
photographs.
In the chart below, describe the shape of each prokaryote.
Visual
Description
Prokaryotic Shapes
Sample answer: Bacilli look like bricks or tubes. Cocci look like
spheres or balls. Spirilla look like curly pasta or crazy straws.
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Structure and Function
Size, Shape, and Movement Prokaryotes come in a variety of shapes. Shape is one way
to tell different prokaryotes apart.
The diagram at the right shows
several kinds of bacteria.
(blue)
(red)
(yellow)
Follow the directions.
1. Color the bacilli blue.
2. Color the cocci red.
3. Color the spirilla yellow.
Answer the questions.
4. Describe the shape of bacilli.
Bacilli are rod-shaped.
5. Describe the shape of cocci.
Cocci are spheres.
6. Describe the shape of spirilla.
Spirilla are spiral- or corkscrew-shaped.
CHAPTER
The Mad Cows In 1986,
there was an outbreak of
“mad cow disease” in Great
Britain. The disease spread
to humans. They had eaten
beef from infected cows.
Look ahead to the “Prions”
text at the end of Section 3.
Then, create a poster that
tells ranchers how to keep
their cows safe. Make sure
the poster explains why it
is important to protect the
food supply.
Students’ work should show that only feed that
is free of cattle tissue should be fed to cows.
Also, a cow that exhibits signs of mad cow disease should be isolated. Posters should explain
that by protecting the food supply, ranchers
are protecting humans from mad cow disease.
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20.3 Diseases Caused by Bacteria
and Viruses
Lesson Objectives
Explain how bacteria cause disease.
Explain how viruses cause disease.
Define emerging disease, and explain why emerging diseases are a threat to human
health.
BUILD Vocabulary
A. The chart below shows key terms from the lesson with their definitions. Complete the chart by
writing a strategy to help you remember the meaning of each term. One has been done for you.
Term
Definition
How I’m Going to Remember
the Meaning
Antibiotic
A drug that blocks the growth
and reproduction of bacteria
Anti- means “against.” Antibiotics fight
against infection by bacteria.
Emerging
disease
An unknown disease that
appears for the first time or
a well-known disease that is
suddenly harder to control
Emerge means “to come into view.”
Pathogen
A microorganism or particle
that causes a disease
It’s pathetic being sick. Patho- means
“disease.”
Prion
An infectious particle made
up of protein only rather than
DNA or RNA
Prions are proteins that pry into a cell
and mess up normal proteins.
Vaccine
A preparation of weakened
or killed pathogens used to
prevent disease
My doctor suggests getting a flu vaccine, or “flu
shot.”
B. As you work through this lesson, you may find these terms in the activities. When you
need to write a key term or a definition, highlight the term or the definition.
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Bacterial Diseases
Bacteria cause disease in two ways. Some bacteria destroy living cells and the tissues of the
infected organisms. Other bacteria release chemicals that upset homeostasis in an organism.
Decide if the methods listed in the chart below control, prevent, or treat bacterial diseases.
Complete the chart.
Method
Control, Prevent, or Treat?
Vaccine
prevent
Physical Removal
control
Sterilization
control
Antibiotics
treat
Disinfection
control
Read the following scenarios. Decide which method of controlling bacteria is being used.
Circle the correct answer.
1. After cooking raw chicken, Miguel always makes sure to wash his hands.
physical removal
disinfection
food storage
2. Louise always uses a food thermometer to make sure her meat is well cooked.
food storage
food processing
sterilization
3. Andrew works in a lab. He always heats his equipment to a temperature of
100 degrees Celsius.
physical removal
sterilization
disinfection
4. Marco puts his lunch in the refrigerator at the office instead of leaving it at his desk.
physical removal
food processing
food storage
BUILD Understanding
Two-Column Chart As you read a lesson, it is helpful to take notes. One way to take notes
is to make a two-column chart. In the left column, write the key questions from the lesson.
In the right column, write answers to the questions. One question has been added for you.
Continue your chart on a separate sheet of paper.
Key Questions
How do bacteria cause disease?
Answers
Bacteria destroy living cells or release
chemicals that upset homeostasis in the
infected organism.
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Inquiry Into Scientific Thinking
MRSA on the Rise In the past, MRSA infection was common only in hospitals. There it
could spread quickly between patients. Scientists are now discovering many more MRSA
cases. The infected people were not hospitalized. They were otherwise healthy. They were,
however, in close contact with large groups of other people. These are called community
associated or CA-MRSA infections.
Look at the graphs below. The graph on the left shows the percent of CA-MRSA
infections in 2000. The graph on the right shows CA-MRSA infections in 2005.
MRSA Infections by Category
2% community
infections
17% community
infections
83% hospital
infections
98% hospital
infections
2005
2000
Analyze and Conclude
1. In 2000, what percentage of total MRSA infections were community-based?
2%
2. In 2005, what percentage of total MRSA infections were community-based?
17%
3. What statement is an accurate interpretation of the data shown on the graphs? Circle the
correct answer.
CA-MRSA infections are on the rise.
CA-MRSA infections are on the decline.
4. Why do you think scientists are concerned about CA-MRSA?
Sample answer: Scientists are concerned because infections are spreading in new
areas.
5. What types of communities might be affected the most by CA-MRSA?
Sample answer: Communities of people that live or work in close proximity and in
large groups. Examples include students, athletes, military personnel, and prisoners.
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309
Name
Class
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Chapter Review
Use the clues and words to help you write the vocabulary terms from the chapter in the
blanks. You may use a word once, more than once, or not at all.
retrovirus
spirillium
vaccine
antibiotic
spirillium
1. An example of a spiral-shaped bacterium is
retrovirus
2. A
bacteriophage
.
is a virus that copies its genetic material from RNA to DNA.
antibiotic
3. A drug that blocks the growth of a bacterial disease is an
.
Answer the following questions.
4. Unicellular organisms that have no nucleus are called
prokaryotes
.
5. Which of the following diseases could be treated with antibiotics?
A. common cold
C. influenza
B. meningitis
D. human papillomavirus (HPV)
6. Complete the compare/contrast table showing the differences between viruses and cells.
Characteristic
Virus
Cell
DNA or RNA in capsid
Cell membrane, cytoplasm;
eukaryotes have nuclei and
organelles.
Reproduction
Only in a host cell
Independent cell division
Genetic code
DNA or RNA
DNA
Responds to environment?
No
Yes
Changes over time?
Yes
Yes
Structure
A
Use the diagram above to answer Questions 7 and 8.
7. The structure shown in this diagram is a
bacterial cell
.
8. What are the structures labeled A in the diagram? Circle your answer.
A. flagella
C. cilia
B. pili
D. ribosomes
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Name
Class
Date
Taking a Standardized Test
Test-Taking Tip: Best Guess
Always guess instead of leaving hard questions unanswered. By guessing, you have a 25%
chance of answering the question correctly. By not answering the question you have a 100%
chance of getting the question wrong.
Read the following question and answer choices.
What is a lytic infection?
A. a bacterial infection in which the cell bursts
B. a viral infection in which the cell bursts
C. a bacterial infection in which the host cell copies the bacterium’s DNA when it reproduces
D. a viral infection in which the host cell copies the DNA of the virus when
it reproduces
Step 1 Read the question carefully. Look for any clues that will help you answer the
question. If there are none, mark the question so you can easily find it again after you finish
the rest of the test.
Step 2 Return to the marked questions. Once you have answered the questions you knew
the answers to, return to the questions you found difficult. Reread the questions.
Step 3 Try to eliminate any answer choices you know are wrong. In this case, you know
that a lytic infection has to do with viruses, and not bacteria. So you can eliminate choices A
and C.
Step 4 Use context clues to make your best guess at an answer. With only two answers
left, you have a 50% chance of getting the question correct. You know the answer is either B
or D. You think you remember that lytic comes from a Greek word that means “to burst.”
The correct answer is B.
Self-Test
Practice what you have learned by answering the following questions. If you find a question
difficult, mark it. Return to it when you have answered all the other questions. If you still
cannot answer it, make your best guess.
1. The common cold is an example of a(n)
A. DNA virus.
C. retrovirus.
B. RNA virus.
D. bacteriophage.
2. An organism that lives in the extreme conditions of a deep sea vent would most likely be
considered a(n)
A. archaea.
C. retrovirus.
B. bacterium.
D. bacteriophage.
3. A type of strep throat is caused by chains of round bacteria cells. This bacteria would be
classified as
A. bacilli.
C. cocci.
B. capsid.
D. spirillium.
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Name
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Date
Use the chart to answer Questions 4–7.
Energy Capture by Prokaryotes
Mode of Nutrition
Habitat
How Energy Is Captured
Example
Heterotroph
Take in organic molecules
from environment or other
organisms to use as both
energy and carbon supply
Wide range of environments
Clostridium
Photoheterotroph
Like basic heterotrophs, but
also use light energy
Where light is plentiful
Rhodobacter, Chloroflexus
Photoautotroph
Use light energy to convert
CO2 into carbon compounds
Where light is plentiful
Anabaena
Chemoautotroph
Use energy released by
In chemically harsh and/or
chemical reactions involving
dark environments: deep in
ammonia, hydrogen sulfide, etc. the ocean, in thick mud,
in digestive tracts of animals,
in boiling hot springs
Nitrosomonas
4. Which phrase would best describe a Clostridium?
A. other feeder
C. light self-feeder
B. light and other feeder
D. chemical self-feeder
5. Which phrase would best describe a chemoautrotrophic prokaryote?
A. other feeder
C. light self-feeder
B. light and other feeder
D. chemical self-feeder
6. In which type of habitat would you find a prokaryote that feeds on light and other energy?
A. deep in the ocean
C. in a chemically harsh environment
B. where light is plentiful
D. in a dark environment
7. Which type of feeder uses light energy to change carbon dioxide into carbon compounds?
A. other feeder
C. light self-feeder
B. light and other feeder
D. chemical self-feeder
Short-Response Question
Answer the following question in two or three sentences.
8. What are the pros and cons of using antibiotic products like hand cleanser and other
cleaning products?
Sample answer: Antibiotic products can help prevent the spread of disease. However,
overuse of these products has led to a process of natural selection that favors emergence of “superbugs” that are resistant to antibiotics.
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