Transcript Organism classification and the scientific method 9/1

Organism classification and the
scientific method
9/1
From the last class-Themes in biology
1.Life is organized in a hierarchy from DNA
molecules to the biosphere
2.Living organisms interact with their
environments, exchanging matter and energy
3.Cells are the structural and functional units of
life
4.All life has common features
Three Domains of Life
Eukaryotes
•Single or multi-cellular
•Membrane-bound
nucleus
•Organelles
Prokaryotes
•Single-celled (mostly)
•No organelles
•No membrane-bound nucleus
Bacteria (multiple kingdoms)
Small in size!
Bacteria (multiple kingdoms)
The most diverse protists!
Archaea (multiple kingdoms)
Extreme environments!
Colony of archaea composed of many cells
100oC and pH of 0
Archaea (multiple kingdoms)
And not-so-extreme
environments…
Protists (multiple kingdoms)
Two major groups we will
look at in this course
Algae
Protozoans
Plants, Fungi and Animals can be
distinguished by how they get their
nutrients
Kingdom Plantae
Diverse, successful, produce their own food
and have cell walls made of cellulose
Molds, yeasts and mushrooms
Decomposers that
recycle nutrients
Kingdom Animalia
Ingest other organisms for food
900,000+ species of
insects may account for
~80% of all animal
diversity
1.6 Evolution explains the unity and
diversity of life
Evolution is a theory. So what does this mean?
Theory-an idea that has been rigorously tested,
supported and generally accepted to be true.
Theories are supported by hypothesis-driven
research and results.
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• In 1859, Charles Darwin published On the Origin
of Species by Means of Natural Selection
The book accomplished two things
1. Presented evidence to support the idea of
evolution
2. Proposed a mechanism for evolution
called natural selection
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Darwin proposed natural selection by connecting
two observations
1. Individuals within a population inherit different
characteristics and vary from other individuals
2. Populations tend to produce more offspring
than can survive to reproduce themselves
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Natural selection is an editing mechanism
Heritable variations in populations respond to
environmental factors  this favors some
individuals over others
Over (evolutionary) time this results in
evolution of new species adapted to
particular environments
Evolution is biology’s core theme and
explains unity and diversity of life
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Inferences
Observations
Individual
variation
Overproduction
of offspring
Natural selection:
unequal reproductive
success
Evolution
of adaptations
in a population
Common Evolutionary Misconceptions
1. Evolution occurs in a population, not in an
individual
Mutations happen in an individual
2. Organisms do not choose to adapt
Changes occur at random
Populations develop diverse characteristics as a
result of their response to the environment,
mutations and exchange with other populations
1
2
1 Population with varied inherited traits
2 Elimination of individuals with certain traits
3 Reproduction of survivors
Evolution can not occur if:
1. There are no differences between individuals
of a population.
2. Mortality is not selective.
3. There are no differences in reproduction
within a population.
Two examples of
adaptive evolution,
from a common
ancestor
Killer whale
Pangolin
Pangolin
Killer whale
THE PROCESS OF SCIENCE
1.7 Scientists use two main approaches to learn
about nature
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Two approaches are used to understand natural
causes for natural phenomena
1. Discovery science—uses verifiable observations and
measurements to describe science
2. Hypothesis-based science—uses the data from
discovery science to explain ideas
This requires proposing and testing of hypotheses
Inquiry is the heart of science
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Examples of Discovery Science
The Human Genome Project
Exploration to
discover new
species
Discovery Science: A lost cause?
Absolutely not!
Here, we make a distinction between
theory and hypothesis
A hypothesis is a proposed explanation for a set of
observations
A theory is supported by a large and usually growing
body of evidence and is accepted by most scientists
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There’s ‘more than one way to skin a cat’
Lab experiments- The most controlled.
Researchers can control most if not all variables.
Field experiment- One variable is changed, but the
natural environment determines the outcome.
Natural experiment- Evolution is a natural
experiment. We have very little control over the
outcome…or do we?
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1.8 With hypothesis-based science, we pose and test
hypotheses
We solve everyday problems by using hypotheses
An example would be the reasoning we use to answer
the question, “Why doesn’t the flashlight work?”
Using deductive reasoning we realize that the problem is
either the (1) bulb or (2) batteries.
The hypothesis must be testable (i.e. Can we design
an experiment to directly support our hypothesis?)
The hypothesis must be falsifiable (i.e. If it truly is
false, can we test it in a way that demonstrates
this?)
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Observations
Question
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burned-out bulb
Observations
Question
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burned-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test prediction
Observations
Question
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burned-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test falsifies hypothesis
Test prediction
Test does not falsify hypothesis
Observations
Question
Hypothesis #1:
Dead batteries
Hypothesis #2:
Burned-out bulb
Hypothesis #1:
Dead batteries
Prediction:
Replacing batteries
will fix problem
Test prediction
Test falsifies hypothesis
Hypothesis #2:
Burned-out bulb
Prediction:
Replacing bulb
will fix problem
Test prediction
Test does not falsify hypothesis
Important! Each
hypothesis involved only
one factor, or variable.
Why wouldn’t we test
both hypotheses together
by changing the batteries
AND light bulb at the same
time?
1.8 Case Study
Another hypothesis: Mimicry helps protect nonpoisonous
king snakes from predators where poisonous coral
snakes also live
The hypothesis predicts that predators learn to avoid
the warning coloration of coral snakes
Mimicry – a resemblance of one organism to another,
usually in an attempt to evade predators.
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1.8 With hypothesis-based science, we pose and test
hypotheses
• Experimentation supports the prediction of the
mimicry hypothesis—nonpoisonous snakes that
mimic coloration of coral snakes are attacked
less frequently
– The experiment has a control group using brown
artificial snakes for comparison
– The experimental group is artificial snakes with the
red, black, and yellow ring pattern of king snakes
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Eastern Coral Snake (poisonous)
Scarlet king snake (non-poisonous)
Red on yellow, kill a fellow
Red on black, friend of Jack.
Coral snake range-blue
Eastern king snake range-red
Predators here do not
interact with coral
snakes (poisonous)
Predators here see
both snakes
Coral snake range-blue
Eastern king snake range-red
1.8 With hypothesis-based science, we pose and test
hypotheses
Non-poisonous snakes that mimic coloration of
coral snakes are attacked less frequently
Control group- brown snake (non-threatening)
Experimental group- artificial snakes with the red,
black, and yellow ring pattern of king snakes
Copyright © 2009 Pearson Education, Inc.
Scientific testing can include assumptions:
What might some assumptions of this
study be?
1. Predators cannot tell a scarlet from a king snake
2. Predators would be interested in the brown snake
100
Percent of total attacks
on artificial snakes
83%
80
Y-axis (dependent variable)
Artificial
(i.e. The data
on snakes
what
84% depends king
the experimental variables are)
Artificial
brown snakes
60
40
20
X-axis (independent variable)
(i.e. What the researcher chooses to
17%test; the
16%experimental variables)
0
Coral snakes
absent
Coral snakes
present
100
84%
Percent of total attacks
on artificial snakes
83%
Artificial
king snakes
80
Artificial
brown snakes
60
40
20
17%
16%
0
Coral snakes
absent
Coral snakes
present
BIOLOGY AND EVERYDAY LIFE
1.9 Biology, technology, and society are connected in
important ways
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• Many of today’s global issues relate to biology
(science)
Many of these issues resulted from applications of
technology
Science and technology are interdependent, but their
goals differ
Science wants to understand natural phenomena
Technology applies science for a specific purpose
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1.10 EVOLUTION CONNECTION: Evolution is connected
to our everyday lives
• How is evolution connected to our everyday
lives?
It explains how all living species descended from
ancestral species
– Differences between DNA of individuals, species, and
populations reflect evolutionary change
The environment matters because it is a selective
force that drives evolution
An understanding of evolution helps us fight disease
and develop conservation efforts
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You should now be able to
1.
2.
3.
4.
Describe life’s hierarchy of organization
Describe living organisms’ interactions with their environments
Describe the structural and functional aspects of cells
Explain how the theory of evolution accounts for the unity and
diversity of life
5. Distinguish between discovery science and hypothesis-based
science
6. Describe ways in which biology, technology, and society are
connected
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Biology
is the study of
(a)
has changed
through the process of
(b)
mechanism is
accounts
for
(c)
leads to
depends on
DNA
(genetic code)
codes for
accounts
for
is evidence of
diversity of life
seen in
(e)
(d)
seen in
variations in
cells as basic
units of life
seen in
common properties
of living organisms
25
Average time to
complete maze (min)
20
15
10
No reward
Food reward
5
0
0
1
2
3
4
5
6
Day
In this experiment, mice learn to run through a maze. Based on the
graph, what is the hypothesis the researchers were testing?
Concept Check
Darwin proposed the theory
of natural selection. For the
most part, natural selection
acts as a filtering agent at the
___________level of life’s
hierarchy.
– Community
– Population
– Individual
– Organ
Answer
Darwin proposed the theory of
natural selection. For the
most part, natural selection
acts as a filtering agent at the
___________level of life’s
hierarchy.
2) Population
Concept Check
Not all scientific discoveries are reached through the “scientific
method.” Which of the following would best be described as
discovery science?
– Looking for a live specimen of an organism found in the
fossil record.
– Describing a new bird species from the Philippines.
– A project to find preserved specimens of the probably
extinct Rocky Mountain locust frozen in glaciers .
– All of the above.
Answer
Not all scientific discoveries are reached through the
“scientific method.” Which of the following would best
be described as discovery science?
4) All of the above.
Interpreting Data
•These two snakes look remarkably similar to each other. The coral
snake (right) is very poisonous to vertebrates. Hypotheses:
•H1: The coral snake’s bright color pattern serves to warn off
potential predators.
•H2: The the king snake suffers less predation because it mimics or
looks like the coral snake.
•H3: The protection that king snakes receive by mimicking coral
snake will depend on the presence of coral snakes.
Interpreting Data
•A team of scientists designed an investigation that used artificial
snakes to test the previous hypotheses. Which of the previous
hypotheses are supported by the results displayed at the right?
1)
H1: The coral snake’s bright color pattern serves to warn off potential
predators.
2)
H2: The the king snake suffers less predation because it mimics or
looks like the coral snake.
3)
H3: The protection that king
snakes receive by mimicking
coral snake will depend on the
presence of coral snakes.
4)
Both 2 and 3
Answer
•A team of scientists designed an investigation that used artificial
snakes to test the previous hypotheses. Which of the previous
hypotheses are supported by the results displayed at the right?
4)
Both 2 and 3
Interpreting Data
Biologists placed artificial snake
mimics in two different localities
to test the hypothesis that looking
like a poisonous snake only works
where the poisonous snake is
found:
1. Outside of the coral snake
range—only king snakes present.
2. Inside the coral snake range—
both coral and king snakes are
present.
Interpreting Data
•The data graphed at the right
__________ the hypothesis that
the effectiveness of mimic
coloration depends upon the
presence of the poisonous model
is:
– supports
– does not support
– is irrelevant to
Answer
•The data graphed at the right
__________ the hypothesis that the
effectiveness of mimic coloration
depends upon the presence of the
poisonous model is:
– supports
Interpreting Data
Based on this data which of the
following is a logical hypothesis or
prediction?
–
–
–
King snakes outside of the range of
coral snakes will more closely
resemble coral snakes than
populations of king snake living within
the range of coral .
King snakes outside of the range of
coral snakes will not resemble coral
snakes as closely as populations of
king snakes that live within the range
coral snakes.
Neither prediction is valid.
Answer
Based on this data which of the following
is a logical hypothesis or prediction?
2)
King snakes outside of the range of
coral snakes will not resemble coral
snakes as closely as populations of
king snakes that live within the range
coral snakes.
Biology and Society
Even a cursory glance at the news media reveals that scientific progress is
an essential part of modern society. Still, many people are very skeptical of
science. Do you think that an informed citizen needs a firm foundation
of understanding of science to effectively participate in a representative
society?
Strongly
Disagree
A
B
C
D
E
Strongly
Agree
Biology and Society
Even a cursory glance at the news media reveals that scientific progress is
an essential part of modern society. Still, many people are very skeptical
of science. Do you think that scientists should take a more active role
in helping society to understand and apply their findings?
Strongly
Disagree
A
B
C
D
E
Strongly
Agree
Biology and Society
Religion and science are often at odds.
Some feel that religion and science are two
powerful but separate ways of human
understanding. Most importantly these
people do not feel that science and religion
are in conflict.
•Do you think that an individual can hold
devout religious beliefs, while at the same
time support scientific understanding?
Strongly
Disagree
A
B
C
D
E
Strongly
Agree
Isn’t evolution just a theory?
http://www.youtube.com/watch?v=85diEX
bJBIk
How does evolution really work?
http://www.youtube.com/watch?v=Pf9P0lr
pgLk