Exploring LifeExploring LifeChapter 1Chapter 1

Advanced Placement BiologyAdvanced Placement Biology

LifeLife Defies a simple, one-line definition.Defies a simple, one-line definition. Lends itself to mysticism.Lends itself to mysticism.

Figure 1.1

What is biology?What is biology?

BiologyBiologyBios Bios = Greek for “life”= Greek for “life”LogosLogos = Greek for = Greek for “study” or “thought”“study” or “thought”

Biology Biology - the study of - the study of living thingsliving things

Concept 1.1: Biologists explore life from Concept 1.1: Biologists explore life from the microscopic to the global scale.the microscopic to the global scale.

The study of life:The study of life:Extends from the microscope scale of Extends from the microscope scale of molecules and cells to the global scale molecules and cells to the global scale of the entire living planet.of the entire living planet.

What does it mean What does it mean to be alive?to be alive?

What characteristics What characteristics define life?define life?

What are the criteria What are the criteria for something to be for something to be

alive?alive?

Figure 1.2

(c) Response to the environment

(a) Order

(d) Regulation

(g) Reproduction (f) Growth and development

(b) Evolutionary adaptation

(e) Energy processing

What does it mean to What does it mean to be “be “livingliving?”?”

Some Characteristics:Some Characteristics:1. 1. OrderOrder- have a - have a hierarchical organization hierarchical organization (Fig 1.3).(Fig 1.3).

A Hierarchy of Biological A Hierarchy of Biological OrganizationOrganization

The hierarchy of lifeThe hierarchy of lifeExtends through many levels Extends through many levels of biological organizationof biological organization

From the biosphere to organisms…From the biosphere to organisms…

Figure 1.3

1 The biosphere

2. Ecosystems

3. Communities4. Populations

5. Organisms

1.a. biome

From cells to atoms.From cells to atoms.Cell

8 Cells

6 Organs and organ systems

7 Tissues

10 Molecules

9 Organelles

50 µm

10 µm

1 µm

Atoms

Figure 1.3

Order Beyond the OrganismOrder Beyond the Organism

PopulationPopulation- a group of - a group of individuals of same species individuals of same species occupying a given area at the occupying a given area at the same time.same time.

Community-Community- a number of a number of interacting populations in a interacting populations in a common environment.common environment.

Order in BiologyOrder in Biology Ecosystem-Ecosystem- organisms (biotic) organisms (biotic)

interacting with their nonliving (abiotic) interacting with their nonliving (abiotic) environment.environment.

Biomes-Biomes- major groupings of plants, major groupings of plants, animals, and microorganisms that occur animals, and microorganisms that occur over a wide geography and have distinct over a wide geography and have distinct characteristics (ex. deserts, tropical characteristics (ex. deserts, tropical rainforests)rainforests)

The Emergent Properties of The Emergent Properties of SystemsSystems

Biological systems are much Biological systems are much more than the sum of their parts.more than the sum of their parts.

Due to Due to increasing complexityincreasing complexityNew properties emerge with New properties emerge with each step upward in the each step upward in the hierarchy of biological orderhierarchy of biological order

The Power and Limitations of The Power and Limitations of ReductionismReductionism

Reductionism-Reductionism-Involves reducing complex Involves reducing complex systems to simpler components systems to simpler components that are more manageable to that are more manageable to study.study.

The study of DNA structure, an The study of DNA structure, an example of reductionismexample of reductionism Has led to further study of heredity, Has led to further study of heredity,

such as the Human Genome Projectsuch as the Human Genome Project

Figure 1.9

A Closer Look at A Closer Look at EcosystemsEcosystems

Each organism…Each organism… Interacts with its environment.Interacts with its environment.

Both organism and Both organism and environment…environment…Are affected by the interactions Are affected by the interactions between them.between them.

Ecosystem DynamicsEcosystem Dynamics The dynamics of any ecosystem The dynamics of any ecosystem

include include two major processestwo major processesCycling of nutrientsCycling of nutrients, in which , in which materials acquired by plants materials acquired by plants eventually return to the soileventually return to the soil

The The flow of energyflow of energy from sunlight from sunlight to producers to consumersto producers to consumers

Energy ConversionEnergy Conversion Activities of life…Activities of life…

Require organisms to perform work, which depends on an Require organisms to perform work, which depends on an energy source.energy source.

The exchange of energy between an organism and its The exchange of energy between an organism and its surroundings involves the surroundings involves the transformationtransformation from one form from one form of energy to another.of energy to another.

Energy flows Energy flows throughthrough an an ecosystemecosystem Usually entering as sunlight and Usually entering as sunlight and

exiting as heatexiting as heat

Producers(plants and other photosynthetic

organisms)

Consumers(including animals)

Sunlight

Chemical energy

Heat

Heat

Ecosystem

Figure 1.4

What does it mean to be What does it mean to be ““livingliving?”?”

2. 2. ResponsivenessResponsiveness or or SensitivitySensitivity- have a response to - have a response to stimuli.stimuli.

ChemotacticChemotactic PhototacticPhototactic ThigmotropicThigmotropic GravitropicGravitropic

Is fire alive?Is fire alive?

A Closer Look at CellsA Closer Look at Cells The cellThe cell

Is the lowest level of organization that Is the lowest level of organization that can perform can perform allall activities required for activities required for lifelife

25 µmFigure 1.5

The Cell’s Heritable InformationThe Cell’s Heritable Information Cells contain chromosomes made Cells contain chromosomes made

partly of DNA, the substance of genespartly of DNA, the substance of genes Which program the cells’ production Which program the cells’ production

of proteins and transmit information of proteins and transmit information from parents to offspringfrom parents to offspring

Egg cell

Sperm cell

NucleicontainingDNA

Fertilized eggwith DNA fromboth parents

Embyro’s cells with copies of inherited DNA Offspring with traits

inherited fromboth parentsFigure 1.6

The molecular structure of DNAThe molecular structure of DNA Accounts for it information-rich nature.Accounts for it information-rich nature.

DNA

Cell

Nucleotide

A

CTA

T

A

C

C

G

G

T

A

T

A

(b) Single strand of DNA. . (a) DNA double helix. Figure 1.7

Nucleus

What does it mean to be What does it mean to be ““livingliving?”?”

3. 3. Growth, Growth, Development, and Development, and ReproductionReproduction- all use - all use hereditary molecules to hereditary molecules to pass genetic pass genetic information to offspring.information to offspring.

Two Main Forms of CellsTwo Main Forms of Cells All cells share certain characteristicsAll cells share certain characteristics

They are all enclosed by a They are all enclosed by a membranemembrane

They all use DNA as genetic They all use DNA as genetic informationinformation

There are There are two main formstwo main forms of cells: of cells:EukaryoticEukaryoticProkaryoticProkaryotic

Prokaryotic cellsProkaryotic cells Lack the kinds of membrane-enclosed Lack the kinds of membrane-enclosed

organelles found in eukaryotic cells.organelles found in eukaryotic cells.EUKARYOTIC CELL

Membrane

Cytoplasm

OrganellesNucleus (contains DNA) 1 µm

PROKARYOTIC CELLDNA (no nucleus)

Membrane

Figure 1.8

What does it mean to be What does it mean to be ““livingliving?”?”

4.4. Regulation Regulation- have - have regulatory mechanisms to regulatory mechanisms to coordinate functions coordinate functions (transportation of nutrients, (transportation of nutrients, wastes, etc.); wastes, etc.); maintainmaintain homeostasishomeostasis..

Feedback Regulation in Feedback Regulation in Biological SystemsBiological Systems

A kind of supply-and-demand economy:A kind of supply-and-demand economy:Applies to some of the dynamics of biological Applies to some of the dynamics of biological systems.systems.

The output, or product, of a process regulates that The output, or product, of a process regulates that very process -very process -feedback regulation.feedback regulation.

In In negative feedback:negative feedback: An accumulation of an end product slows An accumulation of an end product slows

the process that produces that product.the process that produces that product.

B

A

C

D

Enzyme 1Enzyme 1

Enzyme 2

Enzyme 3

DD D D

D

D

DDDD

C

B

A Negative feedback

Figure 1.11

In In positive feedback:positive feedback:The end product speeds up production.The end product speeds up production.

WW

X

Y

Z

ZZ

ZZ

Z

Z Z Z

Z Z Z Z

Z

ZZ Z

ZZ

Y

X

Enzyme 4

Enzyme 5

Enzyme 6

Enzyme 4

Enzyme 5

Enzyme 6

Positivefeedback

Figure 1.12

Question:Question: Are viruses Are viruses alive?alive?

Grouping Species: The Basic IdeaGrouping Species: The Basic Idea

Diversity is a hallmark of life.Diversity is a hallmark of life. TaxonomyTaxonomy::

is the branch of biology that names is the branch of biology that names and classifies species according to a and classifies species according to a system of broader and broader groupssystem of broader and broader groups

Classifying lifeClassifying lifeSpecies Genus Family Order Class Phylum Kingdom Domain

Mammalia

Ursusameri-canus(Americanblack bear)

Ursus

Ursidae

Carnivora

Chordata

Animalia

EukaryaFigure 1.14

The Three Domains of LifeThe Three Domains of Life At the highest level, life is classified into At the highest level, life is classified into three three

domains:domains: BacteriaBacteria ArchaeaArchaea EukaryaEukarya

Domain Bacteria and domain ArchaeaDomain Bacteria and domain Archaea Consist of prokaryotesConsist of prokaryotes

Domain Eukarya, the eukaryotesDomain Eukarya, the eukaryotes Includes the various protist kingdoms and the Includes the various protist kingdoms and the

kingdoms Plantae, Fungi, and Animaliakingdoms Plantae, Fungi, and Animalia

Life’s three domainsLife’s three domains

Figure 1.15

100 µm

0.5 µm

4 µmBacteria are the most diverse and widespread prokaryotes and are now divided among multiple kingdoms. Each of the rod-shapedstructures in this photo is a bacterial cell.

Protists (multiple kingdoms)are unicellular eukaryotes and their relatively simple multicellular relatives.Pictured here is an assortment of protists inhabiting pond water. Scientists are currently debating how to split the protistsinto several kingdoms that better represent evolution and diversity.

Kingdom Plantae consists of multicellula eukaryotes that carry out photosynthesis, the conversion of light energy to food.

Many of the prokaryotes known as archaea live in Earth‘s extreme environments, such as salty lakes and boiling hot springs. Domain Archaea includes multiple kingdoms. The photoshows a colony composed of many cells.

Kindom Fungi is defined in part by thenutritional mode of its members, suchas this mushroom, which absorb nutrientsafter decomposing organic material.

Kindom Animalia consists of multicellular eukaryotes thatingest other organisms.

DOMAIN ARCHAEA

Unity in the Diversity of LifeUnity in the Diversity of Life As diverse as life isAs diverse as life is

There is also evidence of remarkable There is also evidence of remarkable unityunity

Cilia of Paramecium.The cilia of Parameciumpropel the cell throughpond water.

Cross section of cilium, as viewedwith an electron microscope

15 µm

1.0 µm

5 µm

Cilia of windpipe cells. The cells that line the human windpipe are equipped with cilia that help keep the lungs clean by moving a film of debris-trapping mucus upward.Figure 1.16

Concept 1.4: Evolution accounts Concept 1.4: Evolution accounts for life’s unity and diversityfor life’s unity and diversity

The history of lifeThe history of life Is a saga of a changing Earth billions of years oldIs a saga of a changing Earth billions of years old

Figure 1.17

The evolutionary view of The evolutionary view of life…life… Came into sharp focus in 1859 when Came into sharp focus in 1859 when

Charles Darwin published Charles Darwin published On the On the Origin of Species by Natural SelectionOrigin of Species by Natural Selection

Figure 1.18

The Origin of SpeciesThe Origin of Species articulated articulated two main points…two main points… Descent with modificationDescent with modification Natural selectionNatural selection

Figure 1.19

Natural SelectionNatural Selection Darwin proposed natural selectionDarwin proposed natural selection

As the mechanism for As the mechanism for evolutionary adaptation of evolutionary adaptation of populations to their environmentspopulations to their environments

Populationof organisms

Hereditaryvariations

Differences in reproductive success

Evolution of adaptationsin the population

Overproductionand struggle for

existence

Figure 1.20

Natural selection is the evolutionary process that Natural selection is the evolutionary process that occurs…occurs… When a population’s When a population’s heritable heritable

variationsvariations are exposed to environmental are exposed to environmental factors that favor the factors that favor the reproductive reproductive successsuccess of some individuals over others. of some individuals over others.

1 Populations with varied inherited traits

2 Elimination of individuals with certain traits.

3 Reproduction of survivors.

4 Increasing frequency of traits that enhance survival and reproductive success. Figure 1.21

Darwin, 1835, GalapagosDarwin, 1835, Galapagos

Darwin’s Evidence of EvolutionDarwin’s Evidence of Evolution Fossil RecordFossil Record ( (Glyptodont --Glyptodont --

>>armadillo)armadillo) Geographical DistributionGeographical Distribution

(similar climates have unrelated (similar climates have unrelated plants and animals; climate not plants and animals; climate not causing diversity)causing diversity)

Oceanic IslandsOceanic Islands (Galapagos (Galapagos finches and Cape Verde Island finches and Cape Verde Island birds are not similar)birds are not similar)

Darwin’s FinchesDarwin’s Finches

The Galapagos ArchipelagoThe Galapagos Archipelago

Bartoloma IslandBartoloma Island

Isabela IslandIsabela Island

Darwin proposed that natural selectionDarwin proposed that natural selection Could enable an ancestral species to “split” Could enable an ancestral species to “split”

into two or more descendant species, into two or more descendant species, resulting in a “tree of life”resulting in a “tree of life”

Large ground finch Small

groundfinch

Geospizamagnirostris

Seed eater

Sharp-beakedground finch

Camarhynchuspsitacula

Greenwarbler finch

Large tree finchLarge cactus

ground finch

Ground finches Tree finches

Insect eaters Bud eater

Warbler finches

Common ancestor fromSouth American mainland

Graywarbler finch

Certhideaolivacea

Certhideafusca

Geospizadifficilis

Cactus flowereater

Geospizascandens

Seed eater

Geospizaconirostris

Geospizafortis

Mediumgroundfinch

Geospizafuliginosa

Mangrovefinch

Cactospizaheliobates

Cactospizapallida

Woodpeckerfinch

Mediumtree finch

Camarhynchuspauper

Small tree finch

Vegetarianfinch

Camarhynchusparvulus

Platyspizacrassirostris

Cactusground finch

Figure 1.23

Large ground finch Small

groundfinch

Geospizamagnirostris

Seed eater

Sharp-beakedground finch

Camarhynchuspsitacula

Greenwarbler finch

Large tree finch

Large cactusground finch

Ground finches Tree finches

Insect eaters Bud eater

Warbler finches

Common ancestor fromSouth American mainland

Graywarbler finch

Certhideaolivacea

Certhideafusca

Geospizadifficilis

Cactus flowereater

Geospizascandens

Seed eater

Geospizaconirostris

Geospizafortis

Mediumgroundfinch

Geospizafuliginosa

Mangrovefinch

Cactospizaheliobates

Cactospizapallida

Woodpeckerfinch

Mediumtree finch

Camarhynchuspauper

Small tree finch

Vegetarianfinch

Camarhynchusparvulus

Platyspizacrassirostris

Cactusground finch

Figure 1.23

New Evidence that Darwin New Evidence that Darwin Did Not HaveDid Not Have

Age of the EarthAge of the Earth- 4.5 billion year - 4.5 billion year old. Better dating techniques old. Better dating techniques than in Darwin’s time.than in Darwin’s time.

Fossil RecordFossil Record- beginning of life- - beginning of life- 3.5 billion; transitional forms 3.5 billion; transitional forms found. Ex. found. Ex. ArchaeopteryxArchaeopteryx, , feathered (150 million years ago).feathered (150 million years ago).

ArchaeopteryxArchaeopteryx

ArchaeopteryxArchaeopteryx

Transitional Examples?Transitional Examples?

Rodhocetus balochistanensis

Modern Whales

A Walking Whale?A Walking Whale?

Ambulocetus natans

Vestigial StructuresVestigial StructuresExisting structures that Existing structures that have no apparent function, have no apparent function, but resemble structures of but resemble structures of presumed ancestors.presumed ancestors.

Examples:Examples: human human appendix; muscle set in appendix; muscle set in humans for moving ears; humans for moving ears;

New Evidence that New Evidence that Darwin Did Not HaveDarwin Did Not Have

Mechanism of HeredityMechanism of Heredity- - traits through DNA.traits through DNA.

Comparative AnatomyComparative Anatomy (Fig. (Fig. 1.14) Homologous vs. 1.14) Homologous vs. Analogous Structures.Analogous Structures.

The products of natural selectionThe products of natural selection Are often exquisite adaptations of Are often exquisite adaptations of

organisms to the special organisms to the special circumstances of their way of life circumstances of their way of life and their environmentand their environment

Figure 1.22

The Tree of LifeThe Tree of Life Many related organismsMany related organisms

Have very similar anatomical Have very similar anatomical features, adapted for their features, adapted for their specific ways of life.specific ways of life.

Such examples of kinshipSuch examples of kinshipConnect life’s “unity in Connect life’s “unity in diversity” to Darwin’s concept diversity” to Darwin’s concept of “descent with modification.”of “descent with modification.”

Show me an example of Show me an example of homologous structures!homologous structures!

Compare a human Compare a human hand and bat wing.hand and bat wing.

Natural SelectionNatural Selection Natural SelectionNatural Selection- conditions - conditions

in an environment that favor in an environment that favor certain traits of an organism; certain traits of an organism; these traits become more these traits become more common in succeeding common in succeeding generations; must be inheritable; generations; must be inheritable; population gradually changes.population gradually changes.

Darwin’s Theory of Darwin’s Theory of EvolutionEvolution

Natural selection is the Natural selection is the driving force of changes driving force of changes within species populations.within species populations.

Concept 1.5: Biologists use Concept 1.5: Biologists use various forms of inquiry to various forms of inquiry to

explore lifeexplore life At the heart of science is At the heart of science is inquiryinquiry

A search for information and A search for information and explanation, often focusing on explanation, often focusing on specific questionsspecific questions

Biology blends Biology blends two main two main processesprocesses of scientific inquiry of scientific inquiryDiscovery scienceDiscovery scienceHypothesis-based scienceHypothesis-based science

Discovery ScienceDiscovery Science Discovery Science:Discovery Science:

Describes natural structures and Describes natural structures and processes as accurately as processes as accurately as possible through careful possible through careful observation and analysis of data.observation and analysis of data.

Types of DataTypes of Data Data:Data:

Are recorded observations.Are recorded observations.Can be quantitative or qualitative.Can be quantitative or qualitative.

Figure 1.24

Induction in Discovery Induction in Discovery ScienceScience

In In inductive reasoning:inductive reasoning:Scientists derive generalizations Scientists derive generalizations based on a large number of based on a large number of specific observations.specific observations.

Hypothesis-Based Hypothesis-Based ScienceScience

In science, inquiry that asks specific questions:In science, inquiry that asks specific questions:Usually involves the Usually involves the proposing and testingproposing and testing of hypothetical explanations, or of hypothetical explanations, or hypotheses.hypotheses.

Deduction: The “If…then” Logic Deduction: The “If…then” Logic of Hypothesis-Based Scienceof Hypothesis-Based Science

In In deductive reasoning:deductive reasoning:The logic flows from the general The logic flows from the general to the specific.to the specific.

If a hypothesis is correct:If a hypothesis is correct:Then we can expect a particular Then we can expect a particular outcome.outcome.

Inductive vs. Deductive Inductive vs. Deductive ReasoningReasoning

DeductiveDeductive- general principles - general principles are tested and used to examine are tested and used to examine specific cases. Ex. Math and specific cases. Ex. Math and PhilosophyPhilosophy

InductiveInductive- use specific - use specific observations to construct general observations to construct general principles. Ex. Scienceprinciples. Ex. Science

A Biological Example of a A Biological Example of a TheoryTheory

How can living How can living things change things change

over time?over time?

Why do male and female Why do male and female lions look different?lions look different?

Concept 1.6: A set of Concept 1.6: A set of themes connects the themes connects the concepts of biologyconcepts of biology

Underlying themesUnderlying themesProvide a framework for Provide a framework for understanding biologyunderstanding biology

Eleven themes that unify biologyEleven themes that unify biology

Table 1.1

Common Themes in BiologyCommon Themes in Biology Science as a ProcessScience as a Process EvolutionEvolution Energy TransferEnergy Transfer Continuity and ChangeContinuity and Change Relationship of Structure and FunctionRelationship of Structure and Function RegulationRegulation Interdependence in NatureInterdependence in Nature Science, Technology, and SocietyScience, Technology, and Society

How many moths do you see?How many moths do you see?