Download Lesson 1: How are traits inherited?

How are traits inherited?
A. From Parent to Offspring
1. The passing of traits from parents to offspring is called
.
2. The study of how traits pass from parents to offspring is
called
.
a. All organisms have
, which determine everything
from an organism’s shape to its life functions.
b. For most organisms, genes are sections of
that
contain information about a specific trait of that organism.
c. A(n)
is a gene with different information for a trait.
d. Coiled strands of DNA are called
.
B. How are traits inherited?
1. An organism passes its
to its offspring in one of two
ways—through asexual reproduction or through sexual reproduction.
a. In
reproduction, one organism makes a copy of its
genes and itself.
b. In
reproduction, offspring receive half of their genes
from an egg cell and the other half from a sperm cell.
2. An individual organism
the traits in the genes it inherited.
3. Inherited traits differ from
, or learned, traits.
C. Why do scientists study genetics?
1. Scientists began studying genetics to understand how traits
are
.
2. Genetics has helped scientists learn that genes control how organisms
; for example, genes control limb development, body
segmentation, and the formation of , such as eyes and ears.
3. By studying the genetics of development, scientists have learned about
in humans.
4. By studying genetics, scientists can determine how organisms are
and how recently they shared a
common
10
.
Heredity and How Traits Change
Name
Date
Class
Lesson Outline continued
D. Heredity—the History and the Basics
1. The selection and breeding of organisms for desired traits is
called
.
2. Over time, people have successfully used selective breeding to slowly improve
and farm animals.
3. Gregor
began experimenting to answer the question
of how
are inherited in 1856.
a. To test his ideas, Mendel carefully selected
plants
with specific traits and
them.
b. Mendel’s crosses between
for each trait he tested
produced a 3:1 ratio of different traits.
4. Mendel proposed that instead of
, some traits of
organisms are
, and others
are
.
a. A genetic factor that blocks another genetic factor is called a(n)
trait.
b. A genetic factor that is blocked by the presence of a dominant factor is called a(n)
trait.
c. When an individual has one dominant allele and one recessive allele for a trait,
the
5. Which
trait is expressed.
are present on a pair of
determines whether an individual has the dominant
or the recessive trait.
a. The alleles of all the genes on an organism’s chromosomes make up the
organism’s
b. An organism’s
.
is how an organism’s traits appear, or
are expressed.
c. A(n)
d. A(n)
Heredity and How Traits Change
organism has two different alleles for a trait.
organism has two identical alleles for a trait.
11
Lesson 1: How are traits inherited?
A. From Parent to Offspring
1. The passing of traits from parents to offspring is called heredity.
2. The study of how traits pass from parents to offspring is called genetics.
a. All organisms have genes, which determine everything from an organism’s shape
to its life functions.
b. For most organisms, genes are sections of DNA that contain information about a
specific trait of that organism.
c. A(n) allele is a gene with different information for a trait.
d. Coiled strands of DNA are called chromosomes.
B. How are traits inherited?
1. An organism passes its traits to its offspring in one of two ways—through asexual
reproduction or through sexual reproduction.
a. In asexual reproduction, one organism makes a copy of its genes and itself.
b. In sexual reproduction, offspring receive half of their genes from an egg cell and
the other half from a sperm cell.
2. An individual organism expresses the traits in the genes it inherited.
3. Inherited traits differ from acquired, or learned, traits.
C. Why do scientists study genetics?
1. Scientists began studying genetics to understand how traits are inherited.
2. Genetics has helped scientists learn that genes control how organisms develop; for
example, genes control limb development, body segmentation, and the formation
of organs, such as eyes and ears.
3. By studying the genetics of development, scientists have learned about diseases in
humans.
4. By studying genetics, scientists can determine how organisms are related and how
recently they shared a common ancestor.
D. Heredity—the History and the Basics
1. The selection and breeding of organisms for desired traits is called selective breeding.
2. Over time, people have successfully used selective breeding to slowly improve crops
and farm animals.
3. Gregor Mendel began experimenting to answer the question of how traits are
inherited in 1856.
a. To test his ideas, Mendel carefully selected pea plants with specific traits and bred
them.
b. Mendel’s crosses between hybrids for each trait he tested produced a 3:1 ratio of
different traits.
4. Mendel proposed that instead of blending, some traits of organisms are dominant,
and others are recessive.
a. A genetic factor that blocks another genetic factor is called a(n) dominant trait.
b. A genetic factor that is blocked by the presence of a dominant factor is called a(n)
recessive trait.
c. When an individual has one dominant allele and one recessive allele for a trait,
the dominant trait is expressed.
5. Which alleles are present on a pair of chromosomes determines whether an
individual has the dominant or the recessive trait.
a. The alleles of all the genes on an organism’s chromosomes make up the
organism’s genotype.
b. An organism’s phenotype is how an organism’s traits appear, or are expressed.
c. A(n) heterozygous organism has two different alleles for a trait.
d. A(n) homozygous organism has two identical alleles for a trait.
Discussion Question
How did Mendel test the blending hypothesis? What results did he get?
Mendel selected pea plants with specific traits and bred them. Mendel chose true-breeding
plants that produced only green pods and crossed them with true-breeding plants that
produced only yellow pods. All the offspring, called hybrids, produced only green pods.
The yellow-pod trait seemed to disappear and not blend with the green-pod trait.
Genetics After Mendel
A. Rediscovering Mendel’s Work
1. After
published his work, it was mostly forgotten until
it was rediscovered in 1900, when the field of
was
beginning to grow.
2. Scientists realized that genes were on
the
in
.
3. Scientists also confirmed that Mendel’s dominant and
factors were actually
.
B. Predicting Genetic Outcomes
1. The chance that a flipped coin will land heads-up is one-half, or
percent.
2. Probabilities are
; they do not
guarantee
.
3. A(n)
cross is a cross between two individuals that are
hybrids for one trait.
4. When Mendel crossed many sets of
plants that
produced green pods, the results were close to the 3:1 ratio he predicted.
5. A(n)
square shows the probability of all possible
genotypes and phenotypes of offspring.
C. Other Patterns of Inheritance
1. When an offspring’s phenotype is a combination of its parents’ phenotypes, it is
called
dominance.
2. In incomplete dominance, both
are expressed,
that looks like a combination, or blend,
producing a(n)
of the parental traits.
3. When both alleles can be independently observed in a phenotype, it is
called
.
4. Some human
5. Human blood type is also an example of
types show codominance.
alleles, or a
gene that has more than two alleles.
Heredity and How Traits Change
27
Name
Date
Class
Lesson Outline continued
chromosomes determine an organism’s
6.
, or sex.
7. A(n)
trait is a trait whose allele is on an X or Y
chromosome.
8. Some traits, such as human height, are controlled by many genes, and the genes
express a range of
9.
.
inheritance occurs when multiple genes determine the
phenotype of a trait.
D. Inheritance of Disease
1. For centuries, scientists have known that many
tend to
be more common in some families than in others.
a. A(n)
is a diagram that shows genetic traits that were
inherited by members of a family.
to help analyze a family’s
b. Doctors can use a(n)
history.
2. A permanent change in the sequence of DNA in a gene or a chromosome of a cell
is called a(n)
.
a. Diseases are often the result of a mutation in one or more
of an individual.
b. Mutations can produce a change in the appearance or the
of an organism.
c. If a mutation occurs in a(n)
cell, it can be passed
from parent to offspring.
d. Cancer,
, and birth defects can all result from
mutations in genes.
3. In genetic engineering, the genetic material of an organism is modified by inserting
from another organism.
a. The use of bacteria containing a human gene to make human insulin is an
example of
.
b. Scientists can use a gene called GFP to learn how plants respond to changes in
their
28
.
Heredity and How Traits Change
Lesson 2: Genetics After Mendel
A. Rediscovering Mendel’s Work
1. After Mendel published his work, it was mostly forgotten until it was rediscovered
in 1900, when the field of genetics was beginning to grow.
2. Scientists realized that genes were on chromosomes in the nucleus.
3. Scientists also confirmed that Mendel’s dominant and recessive factors were actually
genes.
B. Predicting Genetic Outcomes
1. The chance that a flipped coin will land heads-up is one-half, or 50 percent.
2. Probabilities are predictions; they do not guarantee outcomes.
3. A(n) monohybrid cross is a cross between two individuals that are hybrids for one trait.
4. When Mendel crossed many sets of heterozygous plants that produced green pods,
the results were close to the 3:1 ratio he predicted.
5. A(n) Punnett square shows the probability of all possible genotypes and phenotypes
of offspring.
C. Other Patterns of Inheritance
1. When an offspring’s phenotype is a combination of its parents’ phenotypes, it is
called incomplete dominance.
2. In incomplete dominance, both alleles are expressed, producing a(n) phenotype
that looks like a combination, or blend, of the parental traits.
3. When both alleles can be independently observed in a phenotype, it is called
codominance.
4. Some human blood types show codominance.
5. Human blood type is also an example of multiple alleles, or a gene that has more
than two alleles.
6. Sex chromosomes determine an organism’s gender, or sex.
7. A(n) sex-linked trait is a trait whose allele is on an X or Y chromosome.
8. Some traits, such as human height, are controlled by many genes, and the genes
express a range of outcomes.
9. Polygenic inheritance occurs when multiple genes determine the phenotype of a trait.
D. Inheritance of Disease
1. For centuries, scientists have known that many diseases tend to be more common
in some families than in others.
a. A(n) pedigree is a diagram that shows genetic traits that were inherited by
members of a family.
b. Doctors can use a(n) pedigree to help analyze a family’s history.
2. A permanent change in the sequence of DNA in a gene or a chromosome of a cell is
called a(n) mutation.
a. Diseases are often the result of a mutation in one or more genes of an individual.
b. Mutations can produce a change in the appearance or the function of an
organism.
c. If a mutation occurs in a(n) reproductive cell, it can be passed from parent to
offspring.
d. Cancer, diabetes, and birth defects can all result from mutations in genes.
3. In genetic engineering, the genetic material of an organism is modified by inserting
DNA from another organism.
a. The use of bacteria containing a human gene to make human insulin is an
example of genetic engineering.
b. Scientists can use a gene called GFP to learn how plants respond to changes in
their environments.
Discussion Question
How can bacteria be used to make human insulin?
Scientists discovered the insulin gene in chromosomes in human cells. They inserted the
gene into the DNA of bacteria. The bacteria use the information on the gene to make
human insulin.
Adaptation and Evolution
A. Mutations, Variation, and Natural Selection
1. Mutations can lead to changes in
, which means that
mutations can produce differences among individuals.
2. Slight differences in inherited traits among individuals in a population are
called
.
3. In the 1970s, scientists observed that the
size of a group
of finches changed as a result of changes in their food supply.
4.
is the process by which individuals with variations that
help them survive in their environment live longer, compete better, and reproduce
more than those individuals without these variations.
B. Adaptations
1. An inherited trait that increases an organism’s chance of surviving and reproducing
in a particular environment is called a(n)
.
2. Adaptations can be structural, functional, or
.
a. The flap of skin that enables a flying squirrel to glide through the air is an
example of a(n)
adaptation.
b. Structural adaptations involve
characteristics, such as
color or shape.
c. The smaller
of desert plants are an adaptation that
helps them reduce water loss in a dry environment.
d. Functional adaptations involve
systems that affect an
organism’s physiology or biochemistry.
e. To survive with a short
season, the alpine snowbell
produces flower buds at the end of the previous season.
f.
adaptations, such as migration, involve the ways an
organism behaves or acts.
g. Animal species that migrate to find adequate food and suitable temperatures
survive and
Heredity and How Traits Change
more successfully.
47
Name
Date
Class
Lesson Outline continued
C. Evolution of Populations—Why Traits Change
1. When a(n)
trait has become more frequent in a
population, the population has adapted and evolved.
a. Another way to describe
is change over time.
b. Evolution by natural selection is a way that
change
over time.
c. Species can look and behave differently than their ancestors because the
frequency of
traits changes over time.
2. The evolution of antibiotic-resistant
is a modern
example of change over time.
a. Bacteria that survive when exposed to an antibiotic are
called
.
b. Antibiotic-resistant bacteria are of great concern to scientists because they can
cause deadly
.
D. Extinction and Conservation Biology
1. When a population lacks variation among its individuals and the environment
changes, the population might lose its ability to
successfully and fail to
a.
.
occurs when the last individual of a species dies.
b. New species introduced into many habitats make it difficult for some
species to survive and reproduce.
2. The branch of biology that studies why many species are in trouble and what can
be done to save them is called
biology.
3. Scientists introduced several female panthers from a population in Texas into the
Florida population to increase genetic
in the Florida
population.
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Heredity and How Traits Change
Lesson 3: Adaptation and Evolution
A. Mutations, Variation, and Natural Selection
1. Mutations can lead to changes in traits, which means that mutations can produce
differences among individuals.
2. Slight differences in inherited traits among individuals in a population are called
variations.
3. In the 1970s, scientists observed that the beak size of a group of finches changed as
a result of changes in their food supply.
4. Natural selection is the process by which individuals with variations that help them
survive in their environment live longer, compete better, and reproduce more than
those individuals without these variations.
B. Adaptations
1. An inherited trait that increases an organism’s chance of surviving and reproducing
in a particular environment is called a(n) adaptation.
2. Adaptations can be structural, functional, or behavioral.
a. The flap of skin that enables a flying squirrel to glide through the air is an
example of a(n) structural adaptation.
b. Structural adaptations involve physical characteristics, such as color or shape.
c. The smaller leaves of desert plants are an adaptation that helps them reduce
water loss in a dry environment.
d. Functional adaptations involve internal systems that affect an organism’s
physiology or biochemistry.
e. To survive with a short growing season, the alpine snowbell produces flower
buds at the end of the previous season.
f. Behavioral adaptations, such as migration, involve the ways an organism
behaves or acts.
g. Animal species that migrate to find adequate food and suitable temperatures
survive and reproduce more successfully.
C. Evolution of Populations—Why Traits Change
1. When a(n) inherited trait has become more frequent in a population, the population
has adapted and evolved.
a. Another way to describe evolution is change over time.
b. Evolution by natural selection is a way that populations change over time.
c. Species can look and behave differently than their ancestors because the
frequency of genetic traits changes over time.
2. The evolution of antibiotic-resistant bacteria is a modern example of change over
time.
a. Bacteria that survive when exposed to an antibiotic are called antibioticresistant.
b. Antibiotic-resistant bacteria are of great concern to scientists because they
can
cause deadly infections.
D. Extinction and Conservation Biology
1. When a population lacks variation among its individuals and the environment
changes, the population might lose its ability to reproduce successfully and fail to
survive.
a. Extinction occurs when the last individual of a species dies.
b. New species introduced into many habitats make it difficult for some native
species to survive and reproduce.
2. The branch of biology that studies why many species are in trouble and what can
be done to save them is called conservation biology.
3. Scientists introduced several female panthers from a population in Texas into the
Florida population to increase genetic diversity in the Florida population.
Discussion Question
How do antibiotic-resistant bacteria evolve?
Some bacteria in a population already might have a mutation that enables them to survive
when exposed to an antibiotic. When the surviving bacteria reproduce, that trait passes to
their offspring. Soon, most individuals in the population survive when they are exposed to
the antibiotic.