AP BiologyAP Biology

Intro Notes: Themes in the Intro Notes: Themes in the Study of LifeStudy of Life

Life’s Hierarchical OrderLife’s Hierarchical Order

Each level of biological structure builds Each level of biological structure builds on the level below iton the level below it

AtomsAtomscomplex biological complex biological moleculesmolecules subcellular subcellular organellesorganellescellscellstissuestissues organsorgansorgan systemsorgan systems

Organism

Groups ofCells

Cells

Molecules

Individual livingthing

Tissues, organs,and organ systems

Smallest functionalunit of life

Groups of atoms;smallest unit of most chemicalcompounds

Bison

Nervous tissue Nervous systemBrain

Nerve cell

Water DNA

Levels of Organization

Organism in a

There are levels of organization beyond the There are levels of organization beyond the individual organism:individual organism:

PopulationPopulation-localized group of organisms -localized group of organisms belonging to the same speciesbelonging to the same species

CommunityCommunity- populations of species living in - populations of species living in the same areathe same area

EcosystemEcosystem-energy processing system of -energy processing system of community interactions that include the community interactions that include the abiotic factors in the environmentabiotic factors in the environment

BiomesBiomes- large scale communities - large scale communities classified by predominant vegetation classified by predominant vegetation type and distinctive combinations of type and distinctive combinations of plants and animalsplants and animals

BiosphereBiosphere- the sum of all the - the sum of all the planet’s ecosystemsplanet’s ecosystems

Biosphere

Ecosystem

Community

Population

The part of Earththat contains allecosystems

Community and its nonliving surroundings

Populations thatlive together in a defined area

Group of organisms of onetype that live in the same area

Biosphere

Hawk, snake, bison, prairie dog, grass, stream, rocks, air

Hawk, snake, bison, prairie dog, grass

Bison herd

Levels of Organization, cont.

Emergent properties Emergent properties (pg. 5)(pg. 5)

Each level of biological organization Each level of biological organization has has emergent propertiesemergent properties

These are properties that emerge as These are properties that emerge as a result of interactions between a result of interactions between componentscomponents

Some emergent properties and processes Some emergent properties and processes associated with life are the following:associated with life are the following:

OrderOrder-organisms are highly ordered. -organisms are highly ordered. Characteristics of life emerge from this Characteristics of life emerge from this complex organization.complex organization.

ReproductionReproduction- organisms reproduce - organisms reproduce their own kind; Life comes only from life their own kind; Life comes only from life (biogenesis)(biogenesis)

Growth and development-Growth and development-InheritedInherited information in DNA directs species- specific information in DNA directs species- specific patterns of growth and developmentpatterns of growth and development

EnergyEnergy UtilizationUtilization-Organisms take in -Organisms take in energy and transform it to do work, including energy and transform it to do work, including maintaining their ordered statemaintaining their ordered state

Response to the environment-Response to the environment- Organisms Organisms respond to environmental stimulirespond to environmental stimuli

HomeostasisHomeostasis- Regulatory mechanisms - Regulatory mechanisms maintain an organism’s internal maintain an organism’s internal environment within tolerable limits, even environment within tolerable limits, even though the external surroundings may though the external surroundings may change.change.

Evolutionary adaptations-Evolutionary adaptations- Life evolves Life evolves as a result of the interaction between as a result of the interaction between organisms and their environments.organisms and their environments.

Cells are an organism’s Cells are an organism’s basic unit of structure and basic unit of structure and functionfunction

All organisms are composed of cellsAll organisms are composed of cells Cells exist as unicellular organisms, Cells exist as unicellular organisms,

or as subunits of multicellular or as subunits of multicellular organismsorganisms

Cells are the lowest level of structure Cells are the lowest level of structure capable of performing all life capable of performing all life activities.activities.

Based on structural organization, Based on structural organization, there are two kinds of cells: there are two kinds of cells: prokaryotes and eukaryotesprokaryotes and eukaryotes

Prokaryotes: Lack membrane-bound organelles and nucleus Found only in archaebacteria and bacteria Generally smaller than eukaryotic cells Almost all have tough external walls

Eukaryotes:Eukaryotes: Found in protists, plants, fungi, and

animals Subdivided by internal membranes,

forming organelles Contains DNA separated from the rest of

the cell; organized into chromosomes found in the nucleus

Plant cells have a cell wall; animal cells do not.

The continuity of life is based on The continuity of life is based on inheritable information in the form inheritable information in the form of DNAof DNA

Biological instructions for an organism’s Biological instructions for an organism’s complex structure and function are coded complex structure and function are coded in DNAin DNA

Each DNA molecule is made of 4 Each DNA molecule is made of 4 nucleotides: adenine, thymine, guanine, nucleotides: adenine, thymine, guanine, and cytosineand cytosine

The linear sequence of these 4 The linear sequence of these 4 nucleotides encode the information in a nucleotides encode the information in a genegene

Hydrogen bonds

Nucleotide

Sugar-phosphate backbone

Key

Adenine (A)

Thymine (T)

Cytosine (C)

Guanine (G)

Structure of DNAStructure of DNASection 12-1

InheritanceInheritance

Inheritance is based on a complex Inheritance is based on a complex mechanism for copying DNA and passing mechanism for copying DNA and passing the information on to offspring.the information on to offspring.

All forms of life use essentially the same All forms of life use essentially the same genetic code.genetic code.

Differences among organisms reflect Differences among organisms reflect differences in nucleotide sequence.differences in nucleotide sequence.

Structure and function are Structure and function are correlated at all levels of biological correlated at all levels of biological organization.organization.

There is a relationship between an There is a relationship between an organism’s structure and how it works.organism’s structure and how it works.

Knowing a structure’s function gives Knowing a structure’s function gives insight about its construction.insight about its construction.

Example: aerodynamic design of a bird’s Example: aerodynamic design of a bird’s wing, internal bone structure, and muscle wing, internal bone structure, and muscle arrangement suitable for flightarrangement suitable for flight

Organisms are open systems that Organisms are open systems that interact continually with their interact continually with their environmentenvironment

Both the organism and the Both the organism and the environment are affected by this environment are affected by this interaction.interaction.

Ecosystem dynamics include Ecosystem dynamics include nutrient cycling and energy flow (Fig. nutrient cycling and energy flow (Fig. 1.7)1.7)

Regulatory mechanisms ensure a Regulatory mechanisms ensure a dynamic balance in living systemsdynamic balance in living systems

Many biological processes are self-Many biological processes are self-regulating (feedback regulation)regulating (feedback regulation)

Positive feedback speeds a process Positive feedback speeds a process up up

Negative feedback slows a process Negative feedback slows a process downdown

Heating system turns on

Thermostat senses temperature change and switches on heating system

Thermostat senses temperature change and switches off heating system

Room temperature decreases

Examples of Feedback Inhibition

Evolution, Unity, and DiversityEvolution, Unity, and Diversity

Biological diversity is enormous. Biological diversity is enormous. Estimates range from 5 million to over 30 Estimates range from 5 million to over 30 million species.million species.

About 1.5 million species have been About 1.5 million species have been identified and named, including identified and named, including approximately 260,000 plants, 50,000 approximately 260,000 plants, 50,000 vertebrates, and 750,000 insects.vertebrates, and 750,000 insects.

TaxonomyTaxonomy

TaxonomyTaxonomy is the branch of biology is the branch of biology concerned with naming and classifying concerned with naming and classifying organisms.organisms.

Taxonomic groups are ranked in a Taxonomic groups are ranked in a hierarchy from the most to least inclusive hierarchy from the most to least inclusive category: category: Domain, Kingdom, Phylum, Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Class, Order, Family, Genus, and SpeciesSpecies

Five Kingdoms (traditional Five Kingdoms (traditional classification)classification)

MoneraMonera- prokaryotic organisms - prokaryotic organisms (Bacteria)(Bacteria)

ProtistaProtista- unicellular eukaryotes- unicellular eukaryotes PlantaePlantae-plants, photosynthetic -plants, photosynthetic

organismsorganisms FungiFungi-fungi, eukaryotic decomposers-fungi, eukaryotic decomposers AnimaliaAnimalia- animals, most obtain food by - animals, most obtain food by

ingestioningestion

Unity Unity

There is unity in the diversity of life There is unity in the diversity of life forms at the lower levels of forms at the lower levels of organization.organization.

Unity of life forms is evident in a Unity of life forms is evident in a universal genetic code, similar universal genetic code, similar metabolic pathways, and similarities metabolic pathways, and similarities of cell structure.of cell structure.

Evolution is the core theme of Evolution is the core theme of BiologyBiology

Life evolves as species change over time.Life evolves as species change over time. Species that are very similar share a common Species that are very similar share a common

ancestor at a recent branch point on the ancestor at a recent branch point on the phylogenetic tree.phylogenetic tree.

Less closely related organisms share a more Less closely related organisms share a more ancient common ancestor.ancient common ancestor.

Natural selectionNatural selection is the mechanism of is the mechanism of evolutionary change (survival of the fittest)evolutionary change (survival of the fittest)

Science as a ProcessScience as a Process

Testable hypotheses are the hallmarks of Testable hypotheses are the hallmarks of the scientific processthe scientific process

Scientific method is the process which Scientific method is the process which outlines a series of steps used to answer outlines a series of steps used to answer questions. (questions. (Controlled experimentsControlled experiments))

Science is based on the conviction that Science is based on the conviction that natural phenomena have natural causes.natural phenomena have natural causes.

Evidence is required to solve problemsEvidence is required to solve problems

Scientific HypothesesScientific Hypotheses

Are possible explanationsAre possible explanations Reflect past experienceReflect past experience Multiple hypotheses should be proposed Multiple hypotheses should be proposed

whenever possiblewhenever possible Hypotheses must be testable using the Hypotheses must be testable using the

hypothetico-deductive approachhypothetico-deductive approach Hypotheses can be eliminated but not Hypotheses can be eliminated but not

confirmed with absolute certaintyconfirmed with absolute certainty

Reznick and Elder research

Showed that selective predation resulted in evolution over a short time period

Science and technologyScience and technology

Science and technology are functions of Science and technology are functions of society, and are interdependent.society, and are interdependent.

Technology extends our ability to observe and Technology extends our ability to observe and measure so that scientists can work on new measure so that scientists can work on new questions. questions.

Science generates information to make Science generates information to make technological inventions possibletechnological inventions possible

Technology has improved our standard of Technology has improved our standard of living, but not without environmental and living, but not without environmental and ethical consequences.ethical consequences.

Biology is a muliti-disciplinary Biology is a muliti-disciplinary adventureadventure

Biology integrates concepts from Biology integrates concepts from chemistry, physics, and mathematics, chemistry, physics, and mathematics, with influences from humanities and with influences from humanities and social sciences.social sciences.

As a science, biology is an ongoing As a science, biology is an ongoing process. New research methods and process. New research methods and technologies have led to an “information technologies have led to an “information explosion”explosion”