UNIFYING THEMES OF BIOLOGYCell. Nerve cell. Tissue. Nervous tissue. Organ. Brain. Organelle. Nucleus. Molecule. DNA. Atom. Organism . Brown pelican. Organ system. Nervous system. Brain.
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UNIFYING THEMES OF BIOLOGY
Copyright © 2009 Pearson Education, Inc.
Cells are the structural and functional units of life
Two distinct groups of cells exist– Prokaryotic cells
– Simple and small
– Bacteria are prokaryotic
– Eukaryotic cells– Possess organelles separated by membranes
– Plants, animals, and fungi are eukaryotic
Copyright © 2009 Pearson Education, Inc.
DNA(no nucleus)
Prokaryotic cell
Membrane
Eukaryotic cell
Nucleus(contains DNA)
Organelles
Cells are the structural and functional units of life (continued)
Unicellular organisms
Multicellular organisms
Copyright © 2009 Pearson Education, Inc.
Cells are the structural and functional units of life (continued)
Form generally fits function– By studying a biological structure, you can determine
what it does and how it works (from molecules to organisms!)
– Life emerges from interactions of structures
– Combinations of structures (components) provide organization called a system
Copyright © 2009 Pearson Education, Inc.
In life’s hierarchy of organization, new properties emerge at each level
Life’s levels of organization define the scope of biology Life emerges through organization of various levels With addition of each new level, novel properties
emerge—called emergent properties
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Biosphere
EcosystemFlorida coast
CommunityAll organisms onthe Florida coast
PopulationGroup of brown
pelicans
Nucleus
Nerve
Spinal cord
CellNerve cell
TissueNervous tissue
OrganBrain
OrganelleNucleus Molecule
DNA
Atom
Organism Brown pelican
Organ systemNervous system
Brain
Reproduction and Inheritance
Organisms pass their traits from one generation to the next generation via reproduction.
DNA is the molecular basis of life (ALL life on Earth)
DNARNAProtein
The inheritance of genetic material through reproduction explains the continuity of life
Copyright © 2009 Pearson Education, Inc.
Reproduction and Inheritance (continued)
Continuity of life is based on heritable information in the form of DNA DNA–the genetic
material–carries biological information from one generation to the next
EVOLUTION--THE CORE THEME OF BIOLOGY
Copyright © 2009 Pearson Education, Inc.
“Nothing in biology makes sense except in the light of evolution.”
--Theodosius Dobzhansky
Evolution
Evolution explains the unity and diversity of life.
UnityWhat do organisms have in common?
Why do similarities exist?
DiversityAre there differences between organisms of the same
species?
Unity Shared genetic code
Evolutionary relationships
Connected through a common ancestor
Diversity Differences in DNA structure among organisms
Natural selection: selection of some DNA structures over others
Adaptations: naturally selected traits
Natural selection was inferred by connecting two observations Individuals within a population inherit different
characteristics and vary from other individuals
A particular population of individuals produces more offspring than will survive to produce offspring of their own
(Lamarckian evolution and giraffes)
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Population with varied inherited traits1
Elimination of individuals with certain traits2
Reproduction of survivors3
In this example: • Dark-colored
beetles are selected for
• Light-colored beetles are selected against
• Predation is the selective agent
• Dark coloration becomes an adaptation for this population of beetles
Natural selection is an editing mechanism– It results from exposure of heritable variations to
environmental factors that favor some individuals over others
– Over time this results in evolution of new species adapted to particular conditions/environments
– Evolution is biology’s core theme and explains unity and diversity of life
Copyright © 2009 Pearson Education, Inc.
The Three-Domain System
ProtistsPlantsFungiAnimals
Domain Eukarya
Kingdom AnimaliaKingdom Fungi
Archaea (multiple kingdoms)
Domain Archaea
Domain Bacteria
Bacteria (multiple kingdoms)
Protists (multiple kingdoms) Kingdom Plantae
Dr. R.M. Moody
YOU ARE HERE
THE PROCESS OF SCIENCE
Copyright © 2009 Pearson Education, Inc.
Scientists use two main approaches to learn about nature
Two approaches are used to understand natural causes for natural phenomena– Discovery science—uses verifiable observations and
measurements to describe science
– Hypothesis-based science—uses the data from discovery science to explain science
– This requires proposing and testing of hypotheses
Copyright © 2009 Pearson Education, Inc.
Scientists use two main approaches to learn about nature
There is a difference between a theory and a 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
Copyright © 2009 Pearson Education, Inc.
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
– The hypothesis must be falsifiable
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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
BIOLOGY AND EVERYDAY LIFE
Copyright © 2009 Pearson Education, Inc.
CONNECTION: 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 phenomena
– Technology applies science for a specific purpose
Copyright © 2009 Pearson Education, Inc.
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
Copyright © 2009 Pearson Education, Inc.
Individualvariation
Observations
Overproductionof offspring
Natural selection:unequal reproductive
success
Inferences
Evolutionof adaptationsin a population
Types of Inference (Reasoning)
INDUCTIVE INFERENCE: Arriving at a conclusion based on repeated observation. Repeated observation of the phenomenon supports
my hypothesis.
The sun came up yesterday and today, so I predict it will come up tomorrow.
Can only say that our conclusion is probablytrue.
Types of Inference (Reasoning)
DEDUCTIVE INFERENCE: Logical process of using accepted facts to draw conclusions. Expressed using syllogisms:
If A then B (Premise)A (Premise)
therefore, B (Conclusion)
Problem: If the premises are not true, then the conclusions might be wrong.
1. All men are mortal. Socrates is a man, therefore Socrates is mortal.
2. All mammals are warm-blooded. All dogs are warm-blooded. Therefore, all dogs are mammals.
3. All people sweat profusely after running a marathon. You are sweating a lot. Therefore, you must have just run a marathon.
Critical Thinking and Science
Critical thinking is the deliberate process of judging the quality of information before accepting it.
Critical thinking should be a part of your everyday life: When listening to the media
Surfing the internet
Listening to me, reading textbooks, etc.
HOWEVER: YOU MUST BE KNOWLEDGEABLE ABOUT A SUBJECT BEFORE YOU CAN EFFECTIVELY ARGUE OR DISCUSS IT!
Scientists use two main approaches to learn about nature:
Two approaches are used to understand natural causes for natural phenomena:– Discovery/observational science—uses verifiable
observations and measurements to describe natural phenomena (e.g., fossil record, astronomy, etc.)
– Hypothesis-based /Experimental science—uses the data from discovery science to explain natural phenomena.
– This requires proposing and testing hypotheses
Hypotheses
A HYPOTHESIS is a testable explanation for a natural phenomenon.
Hypotheses are:
Formed based on observation and current theory.
“Rejected” or “Not rejected”, never “Proven”
*Hypotheses guide the design of experiments*
Often stated as an “If…then…” statement
Example: Effects of fertilizer and light on plant growth
The Scientific Method: Testing Hypotheses Explore a phenomenon & make observations Construct a question to investigate based on your observations Construct a hypothesis State a prediction based on the evidence Plan and test the hypothesis with an experiment Analyze the data and evidence Form a conclusion based on your results and construct new knowledge
Was the hypothesis rejected or supported? Form an explanation (model) based on your conclusions and
supporting evidence Connect your new knowledge to your prior knowledge and the
knowledge of others (existing theories) Consider follow-up questions for investigations
Theories and Laws
LAWS describe how a system behaves (e.g., the law of gravity).
Biological Rules are Biological laws
Help describe patterns and relationships but not explain how they work.
THEORIES explain those laws.
Explains how laws work.
In our everyday use of the word, it often means “imperfect fact” or “speculation.”
Used similarly to a hypothesis
This is not accurate
In science, a theory is something VERY SPECIFIC!!!
Theories and Laws
A SCIENTIFIC THEORY is something that has been tested many different times, in many different ways, and has not yet been refuted. Theories are supported or rejected by
testing hypotheses. Theories can change!
HOWEVER, theories are rejected ONLY when they: Are replaced by new theories that explain predictions
of the old theory AND make new predictions!
Societal Conflicts
Society’s traditional views of nature sometimes differ with scientific findings (e.g., Capernicus’ heliocentric model and Galileo).
You have to remember that science can only describe and attempt to explain the physical world.
Science vs Pseudoscience
“Pseudo” = false
The only way to spot a fake is to know as much as possible about the real thing!
Science vs PseudoscienceScience…
Results are verifiable and can be reproduced Clear what methods were used to reach conclusions Focus on failed predictions of a theory Progresses; more and more is learned about the process under study Convinces by appeal to evidence No conflicts of interest; no personal financial stake in results of scientific studies
Pseudoscience… Results are not verifiable and cannot be reproduced
Methods are often unknown
Failed predictions are ignored, excused, or even hidden and lied about
No progress is made; nothing concrete is learned
Convinces by appeal to belief or faith
Pseudoscientists often earn some or all of their living selling their “services”
Scientific Experiments
Used to test hypotheses
Conducted under carefully controlled conditions. where experimental variables can be controlled.
Ideally, conditions should be the same for all groups; only change the variable you are interested in.
Scientific Experiments
The INDEPENDENT VARIABLE is the variable the scientist changes in the experiment The DEPENDENT VARIABLE is what the scientist observes/measures in the experiment (the result) A CONTROL group is a group in which no changes are made. It used as a standard for comparison. A TREATMENT (experimental) group is subjected to the same conditions as the control group except for the variable(s) being studied.
Qualitative vs Quantitative Data QUALITATIVE DATA Deals with descriptions (qualitative = quality)
Data that can be observed but not measured
E.g.) colors, textures, smells, tastes, appearance, relative size, etc.
QUANTITATIVE DATA Deals with numerical descriptions (quantitative =
quantity)
Data that can be measured
E.g.) length, height, area, volume, mass, temperature, time, velocity, etc.
Fertilizer Experiment
1) State a hypothesis
2) State a prediction
3) Identify the experimental groups
4) What could be used as a control group?
5) Identify the dependent variable
6) Identify the independent variable
Sampling Error and Replication
It is important to conduct multiple trials with each independent variable. This is called replication.
Why replicate? What do you do with data from multiple trials/observations?
Researchers cannot measure every individual in a population; data collected from a sample of the population.
Sampling errors occur when conclusions inferred from the collected sample differ from the whole population.
Occurs when sample sizes are small. Sampling error can be reduced by using a larger sample size
Vitamin C and Cancer in Mice
It has been suggested that vitamin C supplements lower the risk of cancer in mammals. You are given 100 mice that have been bred to have an identical genetic make-up. You are asked to design an experiment to address the question of whether vitamin C lowers the risk of cancer in mice.
1)Form a hypothesis2)State a prediction3)Design an experiment to test your hypothesis4) Identify the following:
a) Control group; b) Treatment group, c) Independent variable, and d) Dependent variable
Graphs
Graphs help you interpret and communicate your results.
Graphs show the relationship between your dependent and independent variables. Independent variable (X-axis): What you change
Dependent variable (Y-axis): What is measured
Type of graph used depends on the type of data being presented: Continuous Data
Discrete (categorical) Data
Graphs
Include: Descriptive title
Axes labels
Appropriate scales
Change appearance of points/lines if plotting more than one data set on the same graph Use different colors
Solid vs dashed lines
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