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Biology Semester Review
Fall 2009
The Nature of Science
Scientific MethodScientific MethodPROBLEM / QUESTIONPROBLEM / QUESTION
OBSERVATIONOBSERVATION
HYPOTHESISHYPOTHESIS
EXPERIMENTEXPERIMENT
COLLECT DATACOLLECT DATA
ANALYSISANALYSIS
CONCLUSIONCONCLUSION
REFINE, RETESTREFINE, RETEST
Observation vs. InferenceObservation vs. Inference
ObservationObservation
– Used to Used to collect datacollect data
– States a factStates a fact
InferenceInference
– Used to Used to interpret datainterpret data
– States a States a conclusionconclusion
Variables in an experimentVariables in an experiment
• Independent variable:Independent variable:- variable - variable being changed by youbeing changed by you
• Dependent variable:Dependent variable:- variable that is measured/observed- variable that is measured/observed- responds to the independent - responds to the independent
variablevariable• Constant: Constant:
anything in the experiment that remains anything in the experiment that remains unchanged. unchanged.
Include a ControlInclude a Control
• Something to compare your experimental Something to compare your experimental results to. results to.
• Helps us determine that the results were Helps us determine that the results were caused by the variables in our experiment.caused by the variables in our experiment.
• May be considered the “normal” conditions.May be considered the “normal” conditions.
Testing a HypothesisTesting a Hypothesis
• What are you “What are you “testingtesting” in the ” in the experiment?experiment?– This is the This is the INDEPENDENTINDEPENDENT variable variable– (Same as (Same as MANIPULATEDMANIPULATED variable) variable)
• What effect will you be What effect will you be measuringmeasuring in in your experiment?your experiment?– This is the This is the DEPENDENTDEPENDENT variable variable– (Same as (Same as RESPONDINGRESPONDING variable) variable)
Hypothesis vs. TheoryHypothesis vs. Theory• A A THEORYTHEORY is: is:
– a a well-testedwell-tested explanation that unifies a explanation that unifies a broad range of observationsbroad range of observations
– supported by supported by muchmuch data collected from data collected from manymany experiments and observations. experiments and observations.
• A A HYPOTHESISHYPOTHESIS is: is:– an prediction about the outcome of a an prediction about the outcome of a singlesingle
experiment.experiment.– supported or not supported based on one supported or not supported based on one
experiment.experiment.– must be must be testabletestable– not an opinionnot an opinion
AccuracyAccuracy
• How close the measured value is How close the measured value is to the true or accepted value.to the true or accepted value.
• ExampleExample : If an object has a real mass of 2 grams and the balance used gives a reading of 2 grams, the measurement is accurate. If the balance reads 1.8 grams it is inaccurate.
PrecisionPrecision
• How close together a group of measurements actually are to each other.
• Example: If an object has a mass of 2 grams and a person masses it as 5 g three time in a row. The person shows precision (but not accuracy)
Which ruler is more Which ruler is more precise?precise?
Data CollectionsData Collections
QuantitativeQuantitative
– A measurement A measurement that uses that uses numbersnumbers
– Ex. The plant Ex. The plant grew 12 cm.grew 12 cm.
QualitativeQualitative
– Descriptive Descriptive observationobservation
– Ex. The leaves on Ex. The leaves on the plant turned the plant turned brown.brown.
Graphing in Science
• Title the graphTitle the graph• Label and number your axesLabel and number your axes• Scale the graph so it fills up the Scale the graph so it fills up the
spacespace• Include unitsInclude units• Make a keyMake a key
Always……Always……
DRY MIXDRY MIX• DDependent ependent RResponding esponding yy-axis-axis
• MManipulated anipulated IIndependent ndependent xx-axis-axis
EXAMPLE:EXAMPLE:
ProblemProblem: : You have a massive headacheYou have a massive headache
QuestionQuestion: : Which pill works best?Which pill works best?
-Use 4 different types of pills-Use 4 different types of pills
-Record the speed of time when your -Record the speed of time when your headache is over headache is over
-Concentration of the pills remains the same-Concentration of the pills remains the same
Types of GraphsTypes of Graphs• LINE GRAPH: :
see one variable see one variable over over timetime
• BAR GRAPH: : compares objectscompares objects
• PIE GRAPH: : parts of a whole/ parts of a whole/ percentagepercentage
What are the Characteristics of Living Things? What are the Characteristics of Living Things? Pg. 16Pg. 16
Composed of one or more cells
Reproduction
Universal Genetic Code
Growth & development
Energy use and metabolism
Response to stimuli
Maintenance of homeostasis
Capacity for change (adaptation)
CellsCells
Smallest unit capable of all life functions
Unicellular Organisms - Unicellular Organisms - Entire Entire organism is made up of one single organism is made up of one single cellcell
EX. Bacteria and protistsEX. Bacteria and protists
Multicellular Organisms - Multicellular Organisms - The The organism is made up of many cellsorganism is made up of many cells
Cells have specialized functions Cells have specialized functions within the organismwithin the organism
EX. Trees, Humans, Mushrooms EX. Trees, Humans, Mushrooms
OrganizationOrganization•Atom
•Molecule
•Organelle
•Cell
•Tissue
•Organ
•Organ System
•Multicellular Organism
ReproductionReproduction
All organisms reproduce in order for their species to continue life
Asexual reproduction- involves only a single parent; the offspring would then be genetically identical to its parent
Sexual reproduction- involves 2 parents; this produces genetically diverse offspring
Universal Gentic CodeUniversal Gentic Code
• Genes carry hereditary information
• Genes are composed of DNA
• Determines the inherited traits of every organism on earth
• Heredity is the reason children resemble their parents
Growth & DevelopmentGrowth & Development
Single Celled Organisms – Grow to larger size
Multicellular Organisms – Differentiation for specialized functions
Energy Use & MetabolismEnergy Use & Metabolism
Metabolism- the sum of all chemical processes that occur within a living organism in order to maintain lifeOrganisms use energy to carry out every day functionsAll organisms MUST acquire energy somehow
• Ex. Plants require Sunlight Humans require food
Organisms react to Organisms react to stimuli:stimuli:
LightLight
TemperatureTemperature
OdorOdor
Sound Sound
GravityGravity
HeatHeat
WaterWater
PressurePressure
An example is a An example is a plant’s leaves and plant’s leaves and
stems growing stems growing toward lighttoward light
A stable state of conditions in A stable state of conditions in the body that are necessary for the body that are necessary for
lifelife
Body Body temperaturetemperature
Blood volumeBlood volume
pH balancepH balance
Water balanceWater balance
AdaptatioAdaptationnA process that enables A process that enables
organisms to become better organisms to become better suited to their environmentsuited to their environment
Species obtain adaptations Species obtain adaptations through through evolutionevolution over great over great
periods of timeperiods of time
Evolution- organisms change over time through natural
processes that select individuals with the best
adaptations
What is Geologic Time?What is Geologic Time?•“Eons” – Largest• -“eras”• -“periods”• -“epochs”•Usually the oldest sections are shown on the bottom and the most recent sections are shown on the top
How is Time Divided?How is Time Divided?•Major changes in Earth’s history mark the boundaries between the sections•Most sections have been divided because a major organism developed or went extinct.
Precambrian TimePrecambrian Time
Precambrian TimePrecambrian Time•Time from the formation of the Earth (~4.6 billion years ago) to 542 million years ago
•The Earth was very different then
•-there was no oxygen or living things
•The first organisms appeared
•in the oceans 3.6 billion years ago
•-They were called Prokaryotes
Paleozoic EraPaleozoic Era•Began 542 million years ago and ended 251 million years ago
•Divided into 6 periods
•Many new life forms appeared during the 1st period, the Cambrian Period = “Cambrian Explosion”
•For the first time on Earth, organisms had hard parts (shells, exoskeletons)
•Some organisms that were alive during this period still exist today (ferns and salamanders) but they were giants!
Mesozoic EraMesozoic Era
Mesozoic EraMesozoic Era•Began 251 million years ago•Surviving reptiles and amphibians evolved into many other species (like dinosaurs) = “Age of Reptiles”
Cenozoic EraCenozoic Era
Cenozoic EraCenozoic Era•Began 65 million years ago and continues today
•Scientists know the most about this Era because the fossils are in the top rock layers and are easier to find
•Land & climate has changed a lot
•What big change will happen that will end this era & start the next?
Determining How Old Things AreDetermining How Old Things Are
Fossil RecordFossil Record
When comparing fossils found in rock layers, When comparing fossils found in rock layers, the deeper the layer, the older the fossil.the deeper the layer, the older the fossil.
Water carries small rock particles to lakes and seas
Dead organisms are buried by
layers of sediment, which forms new rock.
The preserved
remains may later be
discovered and studied.
Radiocarbon DatingRadiocarbon Dating
Method of Radiocarbon DatingMethod of Radiocarbon Dating
Radiometric Dating: HistoryRadiometric Dating: History
dinosaurs
humans
first life
origin of Earth
en.wikipedia.org/wiki/Image:Eopraptor_sketch5.png© World Health Org.
© NASA
first complex cells
Geologic Geologic Time and Time and
Earth Earth History History
Ecology
Levels of Organization
Energy Pyramid• Shows the amount of energy available
at each trophic level
100%
10%
1%
0.1%
Primary Consumer
Secondary Consumer
Tertiary Consumer
Producer
L4
L3
L2
L1
• Niche - the total role of a species in an ecosystem – All the physical and biological conditions a
species needs to live & reproduce in an ecosystem
Interactions in an Ecosystem
• Predation – one organism captures and feeds on another
Interactions in an Ecosystem Relationships
Predator – Prey Cycle
SOURCE: Isle Royale Wolf/Moose Study | GRAPHIC: By Patterson Clark, The Washington Post - July 21, 2008
Interactions in an Ecosystem Relationships
• Competition – organisms of the same or different species attempt to use the same resources at the same time
Interactions in an Ecosystem Relationships
• Symbiosis – any relationship in which 2 species live closely together
– Mutualism– Commensalism– Parasitism
Mutualism: Win-Win Relationship
• Both of them benefit
Pollination of flowers by insects Oxpeckers and black rhinoceros
Commensalism: Using without harming
• One is helped and has little or no effect on the other
Burrs are carried by animals. This helps scatter the seeds for the parent plant.
Parasitism: Sponging Off of Others
• One benefits and the other is harmed
MosquitosTapeworms
Limiting Factors
• Biotic or abiotic resource that limits the size of a population
What is the carrying capacity?
• Populations can grow until competition for resources increases & the carrying capacity is reached
Biomagnification
• Concentration of toxin at higher trophic levels
