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Six Criteria of Science
Consistency : The results of
observations and/or experiments are
reasonably the same when repeated.
1.
2.
Green plants will grow towards a light source.
Walking under a ladder will cause bad luck.
Observability : The event or evidence
of the event, can be observed and
explained. The observations are limited
to the basic human senses or to
extensions of the senses.
1.
2.
Some plants eat meat.
Extraterrestrial beings have visited Earth.
Natural : A natural cause (mechanism)
must be used to explain why or how
the event happens.
1. Green plants convert sunlight into energy.
2. With a rod, Moses parted the sea so his
people could cross to the other side..
Predictability : Specific predictions
can be used to foretell an event.
Each prediction can be tested to
determine if the prediction is true or
false.
1.
2.
Without sunlight (or artificial light), green plants will
die.
If you are a "Scorpio", your horoscope for today is
“Lunar position highlights back pay, refunds and
money!!!!!"
Testability : the event must be
testable through the processes of
science, and controlled
experimentation.
1.
2.
The Bermuda Triangle causes ships and
planes to sink and disappear.
Life comes from life and cannot come from
non-life.
Tentativeness : Scientific theories are
changeable and correctable, even to
the point of the theory being proven
wrong. Scientific theories have been
modified and will continue to be
modified
1.
2.
The number of human chromosomes was
once "known" to be 48, but is now considered
to be 46.
We know that the world began about 6000
years ago, and nothing will change that.
Scientific
Method
1.
2.
3.
4.
5.
Observation
Gather Information
Hypothesis
Experiment
Conclusion
Observation
Using senses to gather information
 Observations lead to questions

“what is the effect
of …on …?”
Two types of Observations
Qualitative:
 Uses senses to
describe
 Ex: Mrs. Peddie has
Brown Hair
Quantitative:
 Uses tools to take a
numerical
measurement
 Ex: Mrs. Peddie is
5 ft 2 in.
Hypothesis
 Predicts
the answer to a question
BASED ON:
 Past
experience
 Observations
 Research
The format for writing a hypothesis
“IF . . . THEN . . .because….”
Example : If we increase the temperature
of the fish’s water, then the breathing
rate will increase because breathing
rate is dependent upon temperature.
Experiment
A Test of your hypothesis
 Experiments tests a VARIABLE (factor that changes)
Example: Variable = change in breathing rate
Experiments need a CONTROL GROUP (to compare)
Control Group =breathing rate at room temp

Types of Variables

Dependent Variable:
Is the data collected through observation and
measurement
Ex: Breathing Rate


Independent Variable:
Variable that is manipulated (changed) during
the experiment.
Ex: Water Temp

Conclusion
4 parts:
1.
Did the experiment support the hypothesis?
2.
If you did the experiment again, what would you
do differently?
3.
What did you learn?
4.
Possible Errors
Experimental Design
Activity
Theory
theory = hypothesis supported by
many experiments over time
Examples of theories:
Gravity
Jean Baptiste Lamarck
Evolution occurs as
structures develop
through use, or
disappear because of
disuse, and these
“acquired
EXAMPLE:
characteristics” Over a Giraffes Lifetime it
are passed to offspring
can stretch it’s neck and
it’s offspring will be born
with long necks….
Valid?
Darwin and The Monkey!
THIS IS NOT
WHAT HIS
THEORY
SAYS
Who was Charles Darwin
 Studied
Medicine
 Hated
the sight of
blood
 Received
a BA in
Theology
 Had 10 children
Theory of Evolution


Darwin was an Naturalist on the HMS
Beagle
In The Galapagos Islands, Darwin
collected species of finches (13)
 Each had a specialized diet and way
of obtaining food.
 These finches all closely resembled a
South American finch species
 Hypothesized that the differences
were do to gradual change
Darwin’s Finches
 Darwin
Theory of Evolution
referred to such change as
“descent with modification” –
evolution;
 Wrote Origin of Species
 He still wondered
“How does evolution occur?”
After his voyage, Darwin made
following inferences:
1.
2.
3.
4.
5.
There is variation within populations
Some variations are favorable (better)
Not all young each generation can
survive
Individuals that survive and reproduce
are those with favorable variations
And then those traits will increase in a
population and population will slowly
change
Darwin called this process by which
populations change in response to
their environment
Natural Selection
Evolution happens because
of natural selection
Selection acts on individuals, populations evolve
Change creates advantages
for some species &
disadvantages for others
Fossils reveal changes in species over
millions of years
Adaptation
Adaptations are inherited traits that
increase a group’s chance of
survival & reproduction
This type of finch has a
thick beak  adaptation
for cracking open seeds
Variation
Within a species, there is variation
1.
2.
Variation = differences between
members of a population
Species = group that can breed &
produce healthy offspring
Evidence for Evolution
1. Fossils show change over time


–
scientists can date fossils & use them to
support the theory of evolution
common ancestors reveal whether
species are related
Anatomy of living species also
shows relatedness
How Anatomy supports Evolution
2.
Homologous Structures


Traits similar in different species
because they share a common ancestor
Ex: human arm, dog front limb, horse
leg, whale fin
“ Look the Same”
3. Analogous structures
 Distantly
related species have structures that
have the same function but are different in
structure
 Ex: wing of butterfly & bird
“ Work the Same”
4. Vestigial structures



Structures reduced in size & often
unused
Remains of functional structures
inherited from an ancestor
Ex: leg & hip bones in pythons &
whales
5. Molecular Evidence
Also called biochemical evidence
 Compares biomolecules such as DNA or
amino acid sequences between organisms
 Related organisms have more of the same
molecules in common

How Do New
Species Form?
How do new species form?
1.
Geographic Isolation


When members of a population are
separated
Ex: polar, grizzly, & black bears
2. Reproductive Isolation
 When
members of a population can’t
breed even though they live nearby
 Ex: different mating seasons or different
mating calls
Different Types of Evolution
1.
2.
3.
4.
Divergent evolution
Convergent evolution
Coevolution
Adaptive radiation
Divergent Evolution
Isolated populations
evolve independently
Ex: polar & grizzly bears
changed independently
due to different habitats
Convergent Evolution
Unrelated species become more
alike because they live in similar
environments
Ex: shark & dolphin
Coevolution
Species that interact closely adapt to one
another
Ex: flowers & hummingbirds
Adaptive Radiation
Evolution of many diverse species from
one common ancestor
Ex: famous Galapagos finches discovered
by Darwin
How fast does evolution
occur?
Gradualism
One species
changes slowly &
eventually
becomes two
species
This idea is
supported by
fossil evidence
Punctuated
Equilibrium
Stable with short
periods
of change during which
a new species forms