Concepts & Concepts & Methods in Methods in

BiologyBiologyChapter 1Chapter 1

Biology Biology

Scientific study of lifeScientific study of life

Lays the foundation Lays the foundation for asking basic questions about life for asking basic questions about life

and the natural worldand the natural world

Why Study Biology?Why Study Biology?

To learn how organisms are To learn how organisms are constructed, how they function, constructed, how they function, where they live, and what they do where they live, and what they do

To help develop, modify, and refine To help develop, modify, and refine ideas about lifeideas about life

Molecules of LifeMolecules of Life

All things are made up of the same All things are made up of the same units of matterunits of matter

Living things are made up of a Living things are made up of a certain subset of molecules:certain subset of molecules: Nucleic acidsNucleic acids ProteinsProteins CarbohydratesCarbohydrates Lipids Lipids

DNA (deoxyribonucleic DNA (deoxyribonucleic acid)acid)

Signature molecule of lifeSignature molecule of life

Molecule of inheritanceMolecule of inheritance

Directs assembly of amino acidsDirects assembly of amino acids

DNA and InheritanceDNA and Inheritance

InheritanceInheritance Acquisition of traits by way of Acquisition of traits by way of

transmission of DNA from parent transmission of DNA from parent to offspringto offspring

Reproduction Reproduction Mechanism by which an organism Mechanism by which an organism

produces offspring produces offspring Governed by instructions in DNAGoverned by instructions in DNA

DNA Guides DNA Guides DevelopmentDevelopment

Multicelled organisms develop Multicelled organisms develop

Series of stagesSeries of stages

Instructions for each stage in DNAInstructions for each stage in DNA

Nothing Lives without Nothing Lives without EnergyEnergy

Energy = Capacity to do workEnergy = Capacity to do work

Metabolism = Reactions by which Metabolism = Reactions by which cells acquire and use energy to cells acquire and use energy to grow, survive, and reproducegrow, survive, and reproduce

Sensing and RespondingSensing and Responding

Organisms sense changes in their Organisms sense changes in their

environment and make responses to environment and make responses to

themthem

Receptors detect specific forms of Receptors detect specific forms of

energy (stimuli)energy (stimuli)

Allows maintenance of homeostasisAllows maintenance of homeostasis

Levels of OrganizationLevels of OrganizationCellCell

Multicelled OrganismMulticelled Organism

PopulationPopulation

CommunityCommunity

EcosystemEcosystem

BiosphereBiosphere

Interdependencies Interdependencies among Organismsamong Organisms

ProducersProducersMake their own foodMake their own food

ConsumersConsumersDepend on energy stored in Depend on energy stored in

tissues tissues of producersof producers

DecomposersDecomposersBreak down remains and wastesBreak down remains and wastes

Energy Flow Energy Flow

Usually starts with energy from Usually starts with energy from

sunsun

Transfer from one organism to Transfer from one organism to

anotheranother

Energy flows in one directionEnergy flows in one direction

Eventually, all energy flows back Eventually, all energy flows back

to the environmentto the environment

Producers

Consumers, Decomposers

NUTRIENT CYCLING

ONE-WAY FLOW OF ENERGY

In time, all energy flows back to the environment.

ENERGY FROM SUN

Unity of LifeUnity of Life

All organisms: All organisms:

Are composed of the same substancesAre composed of the same substances

Engage in metabolismEngage in metabolism

Sense and respond to the environmentSense and respond to the environment

Have the capacity to reproduce based Have the capacity to reproduce based

on instructions in DNAon instructions in DNA

Diversity of LifeDiversity of Life

Millions of living speciesMillions of living species

Millions more now extinctMillions more now extinct

Classification schemes Classification schemes

attempt to organize diversityattempt to organize diversity

Scientific NamesScientific Names

Devised by Carolus LinnaeusDevised by Carolus Linnaeus

First name is genus (plural, genera)First name is genus (plural, genera)

Homo sapiensHomo sapiens - genus is - genus is HomoHomo

Second name is species within genusSecond name is species within genus

Eubacteria(Bacteria)

Archaebacteria(Archaea)

Eukaryota(Eukaryotes)

3 Domains3 Domains

Origin of life

EubacteriaArchaebacteria

Eukaryotes

Protistans Plants Fungi Animals

6 Kingdoms6 Kingdoms

Single cells Single cells

No nucleus or No nucleus or

organelles organelles

Smaller, less Smaller, less

complexcomplex

Prokaryotic Prokaryotic Organisms Organisms

Eukaryotic Eukaryotic Organisms Organisms

Single- or multi-Single- or multi-

celled celled

Nucleus and other Nucleus and other

organelles organelles

Larger, more Larger, more

complexcomplex

Mutation: Source of Mutation: Source of VariationVariation

Mutation = change in structure of DNAMutation = change in structure of DNA

Basis for the variation in heritable traitsBasis for the variation in heritable traits

Most are harmfulMost are harmful

Adaptive TraitAdaptive Trait

A trait that gives the individual an A trait that gives the individual an advantage in survival or advantage in survival or

reproduction, under a given set of reproduction, under a given set of circumstancescircumstances

EvolutionEvolution

Genetically based change in a line of Genetically based change in a line of descent over timedescent over time

Population changes, not individualsPopulation changes, not individuals

Artificial SelectionArtificial Selection

Breeders are selective agentsBreeders are selective agents

Individuals exhibiting favored traits Individuals exhibiting favored traits

are bredare bred

Favored traits become more Favored traits become more

common in populationcommon in population

Natural Selection Natural Selection

Individuals vary in some heritable Individuals vary in some heritable traitstraits

Some forms of heritable traits are Some forms of heritable traits are more adaptive more adaptive

Natural selection is differences in Natural selection is differences in survival and reproduction among survival and reproduction among individuals that vary in their traitsindividuals that vary in their traits

Adaptive forms of traits become more Adaptive forms of traits become more common than other formscommon than other forms

Antibiotic ResistanceAntibiotic Resistance

Antibiotics are used to kill bacteriaAntibiotics are used to kill bacteria Mutations for antibiotic resistance Mutations for antibiotic resistance

exist or arise exist or arise Antibiotic-resistant bacteria survive Antibiotic-resistant bacteria survive

and reproduce better than and reproduce better than nonresistantnonresistant

Over time, proportion of antibiotic-Over time, proportion of antibiotic-resistant bacteria increasesresistant bacteria increases

Scientific MethodScientific Method

Observe phenomenonObserve phenomenon

Develop hypotheses Develop hypotheses

Make predictionsMake predictions

Devise test of predictionsDevise test of predictions

Carry out test and analyze Carry out test and analyze

results results

Inductive LogicInductive Logic

Using observations and facts to arrive Using observations and facts to arrive

at generalizations or hypothesesat generalizations or hypotheses

ObservationObservation: Eagles, swallows, and : Eagles, swallows, and

robins have feathersrobins have feathers

HypothesisHypothesis: All birds have feathers: All birds have feathers

Deductive LogicDeductive Logic

Drawing a specific conclusion based Drawing a specific conclusion based

on a generalization on a generalization

GeneralizationGeneralization - Birds have feathers - Birds have feathers

ExampleExample - Eagles are birds - Eagles are birds

ConclusionConclusion - Eagles have feathers - Eagles have feathers

Role of ExperimentsRole of Experiments

Used to study a phenomenon under Used to study a phenomenon under known conditions known conditions

Allows you to predict what will Allows you to predict what will happen if a hypothesis is not wronghappen if a hypothesis is not wrong

Can never prove a hypothesis 100% Can never prove a hypothesis 100% correctcorrect

Experimental Design Experimental Design

Control group Control group A standard for comparisonA standard for comparison Identical to experimental group except Identical to experimental group except

for variable being studiedfor variable being studied

Sampling errorSampling error Nonrepresentative sample skews resultsNonrepresentative sample skews results Minimize by using large samplesMinimize by using large samples

Scientific TheoryScientific Theory

A hypothesis that has been tested for A hypothesis that has been tested for its predictive power many times and its predictive power many times and has not yet been found incorrecthas not yet been found incorrect

Has wide-ranging explanatory powerHas wide-ranging explanatory power Darwin’s theory of evolution by natural Darwin’s theory of evolution by natural

selectionselection

Limits of ScienceLimits of Science

Scientific approach cannot provide Scientific approach cannot provide answers to subjective questionsanswers to subjective questions

Cannot provide moral, aesthetic, or Cannot provide moral, aesthetic, or philosophical standardsphilosophical standards

Conflict with supernatural beliefs Conflict with supernatural beliefs CopernicusCopernicus DarwinDarwin

Scientists Raise Scientists Raise QuestionsQuestions

The external world, not internal The external world, not internal

conviction, must be the testing conviction, must be the testing

ground for scientific beliefsground for scientific beliefs