Transcript Lesson 2

Chapter Introduction
Lesson 1 Inheritance
and Traits
Lesson 2 Adaptations
in Species
Chapter Wrap-Up
How do inherited traits
become adaptations?
What do you think?
Before you begin, decide if you agree or
disagree with each of these statements.
As you view this presentation, see if you
change your mind about any of the
statements.
Do you agree or disagree?
1. Genes are made of chromosomes.
2. A mutation is a permanent change
in a gene.
3. The environment cannot affect an
inherited trait.
Do you agree or disagree?
4. Mutations are a source of variation.
5. All species on Earth are uniquely
adapted to their environments.
6. Plants have adaptations for movement.
Inheritance and Traits
• What is inheritance?
• What is the role of genes in
inheritance?
• How do environmental factors
influence traits?
• How do mutations influence traits?
Inheritance and Traits
• trait
• phenotype
• inheritance
• mutation
• gene
• genotype
What is inheritance?
• A distinguishing characteristic of an
organism is a trait.
• The passing of traits from generation to
generation is inheritance.
What is inheritance? (cont.)
An acquired trait is a
trait that an organism
acquires or develops
during its lifetime.
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What is inheritance?
Inheritance and DNA
Asexual reproduction produces offspring
that are identical to the original organism.
Inheritance and DNA (cont.)
Sexual reproduction
produces offspring that
are similar—but not
identical—to the parent
or parents.
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Inheritance and DNA (cont.)
A gene is a section of DNA that has
genetic information for one trait.
Inheritance and DNA (cont.)
gene
from Greek genea, means
“generation”
Inheritance and DNA (cont.)
• A chromosome is a structure made of
long chains of DNA.
• Humans have 23 pairs of
chromosomes in each body cell.
• Along each of these chromosomes lies
hundreds or thousands of genes.
Inheritance and DNA (cont.)
How are traits and genes
related?
Combining Genes
• In sexual reproduction,
an egg cell and a sperm
cell each contribute one
gene for a trait.
• Meiosis is the process
during which sperm and
egg cells form.
Combining Genes (cont.)
During meiosis, four new reproductive cells
are formed, each with a single set of
chromosomes.
Combining Genes (cont.)
• During fertilization, the egg cell
chromosomes and the sperm cell
chromosomes combine to form an
offspring with a full set of paired
chromosomes.
• Because each sperm cell and egg cell is
unique, the resulting offspring is also
unique.
Influencing Traits
• An organism’s complete set of genes is
its genotype.
• The phenotype of a trait is how the trait
appears, or is expressed.
• Phenotypes result from the interaction of
an organism’s genes and its
environment.
Influencing Traits (cont.)
• Nutrients and other physical factors can
cause dramatic changes in the
phenotype of some organisms.
• An organism’s social group also can
affect color, body structure, or behavior.
Influencing Traits (cont.)
What are some environmental
factors that can influence
phenotype?
Influencing Traits (cont.)
• When an organism’s phenotype changes
in response to its environment, the
organism’s genes are not affected and
the change cannot be passed on to the
next generation.
• The only way that a trait can change so
that it can be passed to the next
generation is by mutation, or changing
an organism’s genes.
Influencing Traits (cont.)
• A mutation is a permanent change in
the sequence of DNA in a gene.
• Some mutations in egg or sperm cells
occur if an organism is exposed to harsh
chemicals or severe radiation, but most
mutations occur randomly.
Influencing Traits (cont.)
How can mutation influence
a trait?
Influencing Traits (cont.)
• Some mutations can affect an
organism’s ability to survive.
• Other mutations might help an organism
to survive.
• Beneficial mutations can spread through
an entire population.
Influencing Traits (cont.)
population
Science Use all the members of a
species living in a given area
Common Use the number of people
living in a country or other defined
area
• Traits are either inherited or acquired.
Inherited traits are passed from one
generation to the next.
• An organism’s phenotype can be
influenced by factors in the
environment, such as light, nutrients,
or social interactions.
• One result of a mutation could be a
change in appearance, such as a
change in feather color.
Which term describes a structure
made of long chains of DNA?
A. chromosome
B. gene
C. genotype
D. phenotype
Which describes how a trait
appears or is expressed?
A. genotype
B. inheritance
C. mutation
D. phenotype
Which results from the interaction
of an organism’s genes and its
environment?
A. gene
B. genotype
C. phenotype
D. trait
Do you agree or disagree?
1. Genes are made of chromosomes.
2. A mutation is a permanent change in a
gene.
3. The environment cannot affect an
inherited trait.
Adaptations in Species
• How do mutations cause variations?
• How does natural selection lead to
adaptations in species?
• What are some ways adaptations help
species survive their own
environments?
Adaptations in Species
• variation
• camouflage
• adaptation
• mimicry
• natural selection
• selective
breeding
What is adaptation?
• Slight differences in inherited traits
among individual members of a species
are variations.
• Variations occur through mutations.
• An adaptation is an inherited trait that
helps a species survive in its
environment.
What is adaptation? (cont.)
adaptation
from Latin adaptare, means
“to adjust”
What is adaptation? (cont.)
How are mutations related
to variations?
How Adaptations Occur
• Natural selection is the process by
which organisms with variations that help
them survive in their environment live
longer, compete better, and reproduce
more than those that do not have the
variation.
• An organism with a beneficial variation
lives longer and has more offspring.
How Adaptations Occur (cont.)
• Over many generations, more and more
offspring inherit the variation.
• Eventually, the variation becomes an
adaptation.
How Adaptations Occur (cont.)
How Adaptations Occur (cont.)
How does a variation
become an adaptation?
How Adaptations Occur (cont.)
• Humans breed organisms by selecting
variations that occur naturally in
populations.
Steven P. Lynch
• The selection
and breeding
of organisms
with desired
traits is
selective
breeding.
Brussel sprouts, cabbage, broccoli, and cauliflower all
have a single ancestor in the mustard family.
Types of Adaptations
• Adaptations enable species to maintain
homeostasis, avoid predators, find and
eat food, and move.
• There are three main categories of
adaptations:
• structural
• behavioral
• functional
Types of Adaptations (cont.)
• The ability of an organism to keep its
internal conditions within certain limits is
homeostasis.
• Sweating on a hot day is an adaptation
that helps you maintain your internal
body temperature.
• All species have adaptations to help
them survive temporary changes in their
environments.
Camouflage is an adaptation that enables
a species to blend in with its environment.
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The camouflaged Stonefish is a predator, snatching up anything
that happens to swim by.
Mimicry is an adaptation in which one
species looks like another species.
Stephen P. Lynch
This orchid mimics a specific female wasp, and is pollinated by
male wasps that attempt to mate with the flower.
Types of Adaptations (cont.)
Give an example of how
adaptations help species
survive.
• Variations in populations occur
because of mutations. Variations can
lead to adaptations.
• Through natural selection, a variation
that helps organisms survive and
reproduce eventually
is inherited by the
entire population.
• Adaptations may be structural,
behavioral, or functional. Structural
adaptations help organisms blend in
with their environments.
Royalty-Free/CORBIS
Which refers to the selection and
breeding of organisms with
desired traits?
A. mimicry
B. natural selection
C. selective breeding
D. variations
What process helps some
organisms survive longer in their
environment?
A. mutation
B. natural breeding
C. natural selection
D. selective breeding
What are slight differences in
inherited traits among individuals
of a species?
A. variations
B. selections
C. mimics
D. breeds
Do you agree or disagree?
4. Mutations are a source of variation.
5. All species on Earth are uniquely
adapted to their environments.
6. Plants have adaptations for movement.
Key Concept Summary
Interactive Concept Map
Chapter Review
Standardized Test Practice
Inherited mutations
can lead to variations,
which can become
adaptations through
natural selection over
many generations.
Lesson 1: Inheritance and Traits
• The passing of traits from generation to generation
is inheritance.
• Information about traits
is passed from parent
to offspring on genes.
• An organism’s
phenotype can be
influenced by environmental factors, such as
temperature, nutrients, and social interaction.
• Only traits affected by mutation can be passed to
offspring.
Lesson 2: Adaptations in Species
• Variations arise when mutations cause changes in
the sequence of an organism’s DNA.
• Natural selection explains how
variations that help organisms
survive are passed to offspring
and eventually become
adaptations.
• Adaptations help species
maintain homeostasis, protect
themselves from predators,
gather food, and move.
During which process do
chromosomes combine to form an
offspring with a full set of paired
chromosomes?
A. mutation
B. meiosis
C. inheritance
D. fertilization
Which refers to an organism’s
complete set of genes?
A. chromosome
B. genotype
C. mutation
D. phenotype
Which refers to reproduction that
produces offspring that are not
identical to the parents?
A. asexual
B. inherited
C. mutated
D. sexual
Which refers to an organism’s
ability to keep its internal
conditions within certain limits?
A. adaptation
B. camouflage
C. homeostasis
D. mimicry
Which enables species to
maintain homeostasis, avoid
predators, find food, and move?
A. selective breeding
B. phenotypes
C. mutations
D. adaptations
Which is the passing of traits
from generation to generation?
A. asexual reproduction
B. inheritance
C. mutation
D. trait
Which refers to a distinguishing
characteristic of an organism?
A. trait
B. phenotype
C. genotype
D. gene
Which is a section of DNA that has
genetic information for one trait?
A. gene
B. genotype
C. phenotype
D. variation
Which enables a species to blend
in with its environment?
A. behavioral adaptation
B. camouflage
C. natural selection
D. mimicry
With which adaptation does one
species look like another species?
A. camouflage
B. mimicry
C. natural selection
D. selective breeding