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 biosphere2.Living organisms interact with their environments, exchanging matter and energy3.Cells are the structural and functional units of life4.All life has common features
Three Domains of Life
Prokaryotes•Single-celled (mostly)•No organelles•No membrane-bound nucleus
Eukaryotes•Single or multi-cellular•Membrane-bound
nucleus•Organelles
Bacteria (multiple kingdoms)
Small in size!
Bacteria (multiple kingdoms)
The most diverse protists!
Extreme environments!Archaea (multiple kingdoms)
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
AlgaeProtozoans
Plants, Fungi and Animals can be distinguished by how they get their nutrients
Kingdom PlantaeDiverse, 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 SelectionThe book accomplished two things
1. Presented evidence to support the idea of evolution2. Proposed a mechanism for evolution called natural
selection
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Darwin proposed natural selection by connecting two observations1. Individuals within a population inherit different
characteristics and vary from other individuals2. Populations tend to produce more offspring
than can survive to reproduce themselves
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Natural selection is an editing mechanismHeritable variations in populations respond to
environmental factors this favors some individuals over othersOver (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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Individualvariation
Observations
Overproductionof offspring
Natural selection:unequal reproductive
success
Inferences
Evolutionof adaptationsin a population
Common Evolutionary Misconceptions
1. Evolution occurs in a population, not in an individual
Mutations happen in an individual2. Organisms do not choose to adapt
Changes occur at random
1
2
Populations develop diverse characteristics as a result of their response to the environment, mutations and exchange with other populations
Population with varied inherited traits1
Elimination of individuals with certain traits2
Reproduction of survivors3
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.
Pangolin
Killer whale
Two examples of adaptive evolution, from a common ancestor
Pangolin
Killer whale
THE PROCESS OF SCIENCE
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1.7 Scientists use two main approaches to learn about nature
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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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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There’s ‘more than one way to skin a cat’
1.8 With hypothesis-based science, we pose and test hypotheses
We solve everyday problems by using hypothesesAn 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?)
Copyright © 2009 Pearson Education, Inc.
Hypothesis #1:Dead batteries
Observations
Question
Hypothesis #2:Burned-out bulb
Hypothesis #1:Dead batteries
Observations
Question
Hypothesis #2:Burned-out bulb
Prediction:Replacing batterieswill fix problem
Prediction:Replacing bulbwill fix problem
Test prediction Test prediction
Hypothesis #1:Dead batteries
Observations
Question
Hypothesis #2:Burned-out bulb
Prediction:Replacing batterieswill fix problem
Prediction:Replacing bulbwill fix problem
Test prediction Test prediction
Test falsifies hypothesis Test does not falsify hypothesis
Hypothesis #1:Dead batteries
Observations
Question
Hypothesis #2:Burned-out bulb
Hypothesis #1:Dead batteries
Hypothesis #2:Burned-out bulb
Prediction:Replacing batterieswill fix problem
Prediction:Replacing bulbwill fix problem
Test prediction Test prediction
Test falsifies hypothesis 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.
Copyright © 2009 Pearson Education, Inc.
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 fellowRed on black, friend of Jack.
Coral snake range-blue Eastern king snake range-red
Coral snake range-blue Eastern king snake range-red
Predators here do not interact with coral snakes (poisonous)
Predators here see both snakes
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
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Scientific testing can include assumptions:What might some assumptions of this
study be?
1. Predators cannot tell a scarlet from a king snake2. Predators would be interested in the brown snake
Artificialking snakes
Artificialbrown snakes
100
Coral snakesabsent
Coral snakespresent
Perc
ent o
f tot
al a
ttac
kson
arti
ficia
l sna
kes
83%
20
40
84%
16%
0
17%
60
80
Y-axis (dependent variable)(i.e. The data depends on what the experimental variables are)
X-axis (independent variable)(i.e. What the researcher chooses to test; the experimental variables)
Artificialking snakes
Artificialbrown snakes
100
Coral snakesabsent
Coral snakespresent
Perc
ent o
f tot
al a
ttac
kson
arti
ficia
l sna
kes
83%
20
40
84%
16%
0
17%
60
80
BIOLOGY AND EVERYDAY LIFE
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1.9 Biology, technology, and society are connected in important ways
• 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 phenomenaTechnology 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 changeThe environment matters because it is a selective
force that drives evolutionAn understanding of evolution helps us fight disease
and develop conservation efforts
Copyright © 2009 Pearson Education, Inc.
You should now be able to
1. Describe life’s hierarchy of organization2. Describe living organisms’ interactions with their
environments3. Describe the structural and functional aspects of cells4. Explain how the theory of evolution accounts for the unity and
diversity of life 5. Distinguish between discovery science and hypothesis-based
science6. Describe ways in which biology, technology, and society are
connected
Copyright © 2009 Pearson Education, Inc.
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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
AnswerDarwin 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 CheckNot 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.
AnswerBased 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?
Disagree Agree
Strongly A B C D E Strongly
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?
Disagree Agree
Strongly A B C D E Strongly
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?
Disagree Agree
Strongly A B C D E Strongly
Isn’t evolution just a theory?http://www.youtube.com/watch?v=85diEXbJBIk
How does evolution really work?http://www.youtube.com/watch?v=Pf9P0lrpgLk