UNIT 5 – CHANGE THROUGH TIME
Guiding Questions
 Where did life come from?
 What types of evidence support the theory of change over time?
 What are the theories of evolution?
 How do environmental pressures cause variations in populations?
What Students Should Know
 In order to develop an understanding of biology as an experimental science, there
must be knowledge of how scientific discoveries are made and how these
discoveries have led to the accumulation of knowledge that is presented in
textbooks. A historical perspective encourages the examination of concrete
examples in the context from which they were developed.
 Although there is not a complete record of ancient life for the past 3.5 billion
years, a great deal of modern knowledge about the history of life comes from the
fossil record.
 A fossil is any evidence of an organism that lived long ago.
 Information about relationships among living organisms and those that inhabited
Earth in the past is gained by comparing developmental stages of organisms and
by examining and interpreting the fossil record. This information is continually
being gathered and used to modify and clarify existing classification systems.
 Genetic mutations and variety produced by sexual reproduction allow for
diversity within a given population.
 Many factors can cause a change in the frequency of a gene over time.
 Depending on the rate of adaptation, the rate of reproduction of an organism, and
the environmental factors present, structural adaptations may take millions of
years to develop.
 Similarities among organisms on the structural and metabolic levels are reflected
in the large degree of similarity in proteins and nucleic acids of different
organisms. Diversity is the product of variations in these molecules.
 Scientists have developed hypotheses about conditions on early Earth that could
have led to the formation of the first organic molecules, early self-replicating
molecules, the source of free oxygen in Earth’s atmosphere, and the appearance of
prokaryotic and later eukaryotic cells.
 Natural selection is a process by which organisms with traits well suited to an
environment survive and reproduce at a greater rate than organisms less suited to
that environment.
 Populations are groups of interbreeding individuals that live in the same place at
the same time, and compete with each other for food, water, shelter, and mates.
 Populations produce more offspring than the environment can support.
 Organisms with certain genetic variations will be favored to survive and pass their
variations on to the next generation.
 The unequal ability of individuals to survive and reproduce leads to the gradual
change in a population, generation after generation.
 Through his observations made in the Galapagos Islands, Charles Darwin
formulated a theory of how species change over time called natural selection.
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Natural selection is governed by the principles of genetics. The change frequency
of a gene in a given population leads to a change in a population and may result in
the emergence of a new species.
Natural selection operates on populations over many generations.
Mutations are important in how populations change over time because they result
in genetic changes to the gene pool.
Adaptations sometimes arise in response to environmental pressures, for example,
the development of antibiotic resistance in bacterial populations, morphological
changes in the peppered moth population, and the development of pesticide
resistance in insect populations.
Stephen Jay Gould’s idea of punctuated equilibrium proposes that organisms may
undergo rapid (in geologic time) bursts of speciation followed by long periods of
time unchanged. This view is in contrast to the traditional evolutionary view of
gradual and continuous change.
Evolution Review
History of Life
 Earth’s first cells were prokaryotes.
 Prokaryotic cells exist in two major forms: eubacteria and archaebacteria.
 Prokaryotes are the Earth’s most abundant inhabitants. They can survive in a wide
range of environments and obtain energy in a variety of ways.
 Eukaryotes arose from prokaryotes and developed into larger more complex
organisms, from single-celled protists to multi-cellular fungi, plants, and animals.
 Several differences between eukaryotes and prokaryotes include size, genetic
material surrounded by a nuclear membrane, and the addition of mitochondria and
chloroplasts.
 Although there is not a complete record of ancient life for the past 3.5 billion
years, a great deal of modern knowledge about the history of life comes from the
fossil record.
o A fossil is any evidence of an organism that lived long ago.
o Scientists have used the fossil record to construct a history of life on Earth.

Information about relationships among living organisms and those that inhabited
Earth in the past is gained by comparing developmental stages of organisms
(embryological development) and by examining and interpreting the fossil
record. This information is continually being gathered and used to modify and
clarify existing classification systems.

Similarities among organisms on the structural and metabolic levels are reflected
in the large degree of similarity in proteins and nucleic acids of different
organisms. Diversity is the product of variations in these molecules.

Genetic mutations and variety produced by sexual reproduction allow for
diversity within a given population.
o Many factors can cause a change in a gene over time.

Depending on the rate of adaptation, the rate of reproduction, and the
environmental factors present, structural adaptations may take millions of years to
develop.

Populations are groups of interbreeding individuals that live in the same place at
the same time and compete with each other for food, water, shelter, and mates.
o Populations produce more offspring than the environment can support.

Organisms with certain genetic variations will be favored to survive and pass their
variations on to the next generation. The ability to survive and reproduce is
described at fitness.

The unequal ability of individuals to survive and reproduce leads to the
gradual change in a population, generation after generation over many
generations (GRADUALISM)

Through his observations made in the Galapagos Islands, Charles Darwin
formulated a theory of how species change over time, called natural selection
(survival of the fittest).

Natural selection is governed by the principles of genetics. The change
frequency of a gene in a given population leads to a change in a population and
may result in the emergence of a new species (speciation). Natural selection
operates on populations over many generations.

Mutations are important in how populations change over time because they result
in genetic changes to the gene pool.
 Adaptations sometimes arise in response to environmental pressures, for
example, the development of antibiotic resistance in bacterial populations,
morphological changes in the peppered moth population, the development of
pesticide resistance in insect populations.

Stephen Jay Gould’s idea of punctuated equilibrium proposes that organisms
may undergo rapid (in geologic time) bursts of speciation followed by long
periods of time unchanged. This view is in contrast to the traditional evolutionary
view of gradual and continuous change (gradualism).
The Theory of Evolution
In science, theories are statements or models that have been tested and confirmed
many times. The theory of evolution is considered a unifying theme in biology
because it explains the unity and diversity of life.
Lamarck's Theory of Acquired Characteristics - Some people
thought that you would gain or lose features if you overused or
didn't use them, and you could pass these new traits onto your
offspring. This was known as the Inheritance of Acquired
Characteristics.
discarded.
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Logically, this does not work and Lamarck’s
theory was
Darwin's Theory of Evolution by Natural Selection
Darwin was a naturalist who observed many species. He is famous for his trips to
the Galapagos Islands, his observations of the finches (and other animals) and the
book he wrote: "The Origin of Species:
1.
Variation
exists
among
individuals
in
a
species.
2. Individuals of species will compete for resources (food and space)
3. Some competition would lead to the death of some individuals while others
would
survive
4. Individuals that had advantageous variations are more likely to survive and
reproduce.
This process he describes came to be known as Natural Selection
The favorable variations are called Adaptations
Evidence of Evolution
1. Fossil Evidence
2. Evidence from Living Organisms
Evidence of Common Ancestry
Homologous Structures--structures that are embryologically similar, but have
different functions, the wing of a bird and the forearm of a human
Vestigial Organs--seemingly functionless parts, snakes have tiny pelvic and limb
bones, humans have a tail bone
Biochemistry and DNA
Embryological development--Embryos of different species develop almost
identically
Observation of species change (wolves/dogs, peppered moths)
UNDERSTANDING EVOLUTION WEB ACTIVITY
Understanding evolution web activity ANSWER KEY
http://evolution.berkeley.edu/evolibrary/article/similarity_hs_01
1. Define the following words:
 Homology - Traits that are inherited by two different organism from a common
ancestor
 Analogy - Traits that are similar due to convergent evolution, not common
ancestry.
2. What is meant by “common ancestor”? A shared ancestor
3. What are structures inherited from a common ancestor? Homologies
4. What are similar structures that evolved independently called? Analogies
5. Are sharks' and dolphins' similarities (body shape, fin, and flippers) homologies or
analogies? Analogies
UNIT 6 – WEB OF LIFE
Essential Questions
 How are organisms classified?
 How are viruses different from living things?
 What are some common characteristics of bacteria, protests, fungi, plants, and
animals?
 How do human and other organisms maintain homeostasis?
What Students Should Know
 Investigations of local flora and fauna provide opportunities to enhance
understanding and stimulate interest in local environmental issues by developing
and applying classification systems in the field.
 Binomial nomenclature is a standard way of identifying a species with a scientific
two-word name. The first word is the genus name and the second the species
name.
 A species is defined as a group of organisms that has the ability to interbreed and
produce fertile offspring.
 Information about relationships among living organisms and those that inhabited
Earth in the past is gained by comparing developmental stages of organisms and
by examining and interpreting the fossil record. This information is continually
being gathered and used to modify and clarify existing classification systems.
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Similarities among organisms on the structural and metabolic levels are reflected
in the large degree of similarity in proteins and nucleic acids of different
organisms. Diversity is the product of variations in these molecules.
The millions of different organisms that live on Earth today share many structural
and metabolic features, including cellular organization, common molecular
mechanisms for energy transformation and utilization and maintenance of
homeostasis, common genetic code, and mechanisms for the transmission of traits
from one generation to the next.
The diversity that is evident in the natural world can be studied in the local
environment in the context of variations on a common theme.
Viruses do not share many of the characteristics of living organisms.
Viruses are not cells. Basic viral structure consists of a nucleic acid core
surrounded by a protein coat.
Viruses can only reproduce inside another living cell, the host cell.
The viral reproductive process is includes the following steps:
- A virus must insert its genetic material into the host cell.
- The viral genetic material takes control of the host cell and uses it to produce
viruses.
- The newly formed viruses are released from the host cell.
Like other organisms, human beings are composed of groups of cells (tissues,
organs, and organ systems) that are specialized to provide the human organism
with the basic requirements for life: obtaining food and deriving energy from it,
maintaining homeostasis, coordinating body functions, and reproducing.
Organ systems function and interact to maintain a stable internal environment that
can resist disturbance from within or without (homeostasis).
Understanding normal body functioning assists in understanding situations, both
hereditary and environmental, in which functioning is impaired.
For the body to use food for energy, the food must first be digested into molecules
that are absorbed and transported to cells, where the food is used for energy and
for repair and growth.
To burn food for the release of energy, oxygen must be supplied to cells and
carbon dioxide removed. The respiratory system responds to changing demands
by increasing or decreasing breathing rate in order to maintain homeostasis.
The circulatory system, which moves all of these substances to or from cells,
responds to changing demands by increasing or decreasing heart rate and blood
flow in order to maintain homeostasis.
The urinary system disposes of dissolved waste molecules; the intestinal tract
removes solid wastes; and the skin and lungs rid the body of heat energy.
Specialized cells of the immune system and the molecules they produce are
designed to protect against organisms and substances that enter from outside the
body and against some cancer cells that arise from within.
Communication between cells is required for coordination of body functions. The
nerves communicate with electrochemical signals, hormones circulate through the
blood, and some cells secrete substances that spread only to nearby cells.
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Environmental factors that impact human health include diet, exercise, sleep,
stress, toxic substances that enter the body, viruses, and other living organisms
that infect the body.
Genetic predisposition towards disease impacts human health. Awareness of
genetic predisposition allows individuals to make lifestyle changes that can
enhance quality of life
Classification review
Classification - the arrangement of organisms into orderly groups based on their
similarities and presumed evolutionary relationships.
Taxonomy is the branch of biology that names and groups organisms according
to their characteristics and evolutionary history.
•
•
Carolus Linnaeus
devised a system for grouping organisms based on their form and structure.
Scientific names
– Two words : Genus species
– Referred to as binomial nomenclature
Levels of Organization
 Domain (Archaebacteria, Eubacteria, Eukaryota)
 Kingdom (Archaebacteria, Eubacteria, Protista, Fungi, Plantae & Animalia)
 Phylum
 Class
 Order
 Family
 Genus
 Species
What is a species?
– a group of organisms that are closely related and can mate to produce
fertile offspring. Species is also the level of classification below genus
– Some organisms appear to be similar but are not closely related at all. This
is the result of convergent evolution (the process by which unrelated
species become similar as they adapt to similar environments)
– In contrast, divergent evolution is the process by which two or more
related species become more and more dissimilar.
•
How do Biologists Classify an Organism?
Cladistics
A
system
of
classification
based
on
shared
derived
traits.
A cladogram is a diagram based on patterns of shared, derived traits that shows
the evolutionary relationships among groups of organisms.
Virus Review
 smaller than bacteria with just a bit of DNA or RNA surrounded by a protein coat,
 are not alive (even though they have genetic material)
 obligate parasites (need a host)
 Replication cycles – lytic or lysogenic
 Examples : HIV, Common Cold, Influenza, Chicken Pox
Bacteria Review
BACTERIA
 Small and simple
 No nucleus or membrane bound organelles (prokaryotes)
 Can be classified by the following:
 Their shape (round, rod, or spiral)
 How they get energy/ niche in ecosystem (autotroph, chemoautotrophs,
consumer),
 How it stains with certain dyes (gram positive or gram negative)
 Can be pathogenic and antibiotics can help fight them.
 Can be beneficial – decomposers, nitrogen fixing, food producing ones.
 Reproduce by binary fission or conjugation
COMPARING VARIOUS ORGANISMS ACTIVITY
COMPARING VARIOUS ORGANISMS ANSWER KEY
The following activity is designed for you to use already acquired information and to use research
methods including the internet, your textbook, and other possible resources. It is a chart that
compares members of each of the 3 major domains and the 4 kingdoms. Some information is
already completed for you.
Biological
Process
unicellular
or
multicellula
r
nucleus
ecological
niche
(producer
or
consumer)
Domain
ARCHAEBACTR
IA
Domain
EUBACTERI
A
Domain EUKARYOTES (kingdoms listed below)
Protist
Fungi
Plant
Animal
ALGAE
MUSHROO OAK
HUMAN
M
TREE
multi and some
uni. multi
multi.
uni
but mostly
multi.
unicellular
Unicellular
no
No
yes
yes
yes
yes
some producers
most consumers
some
producers
some
consumers
some
producer
s
some
consume
rs
consumers
producer
s
consumer
Mobility
motile
or
nonmotile
Reproducti
on
sexual
or
asexual
Habitat
aquatic or
terrestrial
Adaptation
to specific
environmen
t
nonmobile
Nonmobile
both
nonmobile
nonmobi
le
mobile
asexual
mostly
asexual
both
both
sexual
sexual
aquatic
Aquatic
aquatic
terrestrial
terrestrial
both
enzymes
to
withstand extreme
heat
can multiple
quickly and
can
form
spores
protists
can
move
away
from
negative
stimuli
hard
cell
walls to help
protect
long
roots,
tough
layer on
leaves,
bark
various
systems
can change
with
environme
nt