Introduction to Biological Concepts and Research

Chapter 1

1.1 What Is Life? Characteristics of Living Systems

Organized in a hierarchy• Each level with its own emergent properties

Contain chemical instructions• Govern structure and function

Engage in metabolic activities

1.1 (cont.)

Energy flows through; matter cycles

Compensate for changes in external environment

Reproduce and undergo development

Populations change from one generation to the next

Living Organisms

Fig. 1-1, p. 2

Hierarchy of Living Systems (1)

Cells• Lowest level of organization that is alive

Organisms• Unicellular or multicellular

Populations• Groups of organisms of the same kind, living

together in the same area

Hierarchy of Living Systems (2)

Community• All populations living in an area

Ecosystems • Include communities that interact through their

shared physical environment

Biosphere• The highest level

• Includes all Earth’s ecosystems

Hierarchy of Life

Fig. 1-2, p. 3

BiosphereAll regions of Earth’s crust, waters, andatmosphere that sustain life

Fig. 1-2, p. 3

Stepped Art

EcosystemGroup of communities interacting with their shared physical environment

CommunityPopulations of all species that occupy the same area

PopulationGroup of individuals of the same kind (that is, the same species) that occupy the same area

Multicellular OrganismIndividual consisting of interdependent cells

CellSmallest unit with the capacity to live and reproduce, independently or as part of a multi-cellular organism

Fig. 1-2a, p. 3

Cell

Smallest unit with thecapacity to live andreproduce, independentlyor as part of a multi-cellular organism

Fig. 1-2b, p. 3

Multicellular organism

Individual consisting ofinterdependent cells

Fig. 1-2c, p. 3

Population

Group of individuals ofthe same kind (that is,the same species) thatoccupy the same area

Fig. 1-2d, p. 3

Community

Populations of allspecies that occupythe same area

Fig. 1-2e, p. 3

Ecosystem

Group of communitiesinteracting with theirshared physicalenvironment

Fig. 1-2f, p. 3

Biosphere

All regions of Earth’scrust, waters, andatmosphere thatsustain life

Animation: Life’s levels of organization

Information Flow

Living organisms have complex structures• Established by instructions coded in DNA

Information in DNA is copied into RNA• Guides production of protein molecules

Proteins carry out most activities of life

Deoxyribonucleic Acid (DNA)

Fig. 1-3, p. 3

Information Flow

Fig. 1-4, p. 4

Fig. 1-4, p. 4

Information isstored in DNA.

ProteinRNADNA

The information inRNA guides theproduction of proteins.

The informationin DNA is copiedinto RNA.

Metabolism

The activity of obtaining and using energy• Maintenance

• Growth

• Reproduction

Two primary metabolic processes• Photosynthesis

• Cellular respiration

Energy and Matter

Energy• Flows through the hierarchy of life

• Eventually released as heat, which cannot be used by living systems

Matter• Recycled within the biosphere

Metabolism

Fig. 1-5, p. 4

Fig. 1-5, p. 4

Electromagneticenergy in sunlight

Energy is stored aschemical energy.

Sugar Oxygen

Cellular respirationreleases chemical energy from sugar

molecules.

Released chemicalenergy is madeavailable for othermetabolic processes.

Carbon dioxide

Waterand

Photosynthesis captures

electromagnetic energyfrom sunlight.

Oxygen

Oxygen

Cellular respirationreleases chemical energy

from sugar molecules.

Electromagneticenergy in sunlight

Photosynthesis captureselectromagnetic energy

from sunlight.

Energy is stored aschemical energy.

Sugar

Carbon dioxide

Water

and

Oxygen

Fig. 1-5, p. 4

Released chemicalenergy is madeavailable for othermetabolic processes.

Stepped Art

Compensation for Change

Cells and organisms use receptors to detect changes in environment

Triggers a compensating reaction that allows the organism to survive

Reproduction and Development

Organisms reproduce

Offspring develop into mature, reproductive adults

Evolution

Populations undergo biological evolution as generations replace one another over time

Energy Flow and Nutrient Recycling

Fig. 1-6, p. 5

Fig. 1-6, p. 5

Secondary Consumers

Heat Heat

Heat

Heat Heat

Decomposers Primary consumers

NutrientsrecycledSun

Primary Producers

Energy ultimatelylost as heatEnergy transfer

KEY

1.2 Biological Evolution

Darwin and Wallace explained how populations of organisms change through time

Mutations in DNA allow evolutionary change

Adaptations enable organisms to survive and reproduce in their environments

Populations Change With Time (1)

Changes occur in structure, function, types of organisms

Theory of evolution by natural selection• Certain characteristics allow some organisms to

survive better and reproduce more than others in their population

Populations Change With Time (2)

Instructions for characteristics are coded in DNA• Successful characteristics become more common

in later generations

Average characteristics of offspring generation differ from those of parent generation

Life Cycle: Silkworm Moth

Fig. 1-7, p. 6

Fig. 1-7, p. 6

e. Adulta. Egg b. Larva c. Pupa

d. Recentlyemerged adult

Animation: One-way energy flow and materials cycling

Heredity (1)

Genes• Segments of DNA

• Code instructions for many characteristics

• Passed through reproduction from parents to offspring

Heredity (2)

Mutations• Changes in structure, number, or arrangement of

DNA molecules

• Create variability among individuals

Variability• Natural selection and other processes cause

biological evolution

Adaptations

Accumulation of favorable characteristics over many generations may produce adaptations

Enable individuals to survive longer or reproduce more

Artificial Selection

Fig. 1-8, p. 7

Animation: Insect development

Camouflage in Rock Pocket Mice

Fig. 1-9, p. 8

Distributions of Rock Pocket Mice

Fig. 1-10, p. 9

Fig. 1-10, p. 9

New MexicoArizona

Mouse colorArmendarisPinacate

N = 8N = 12N = 5N = 15N = 11N = 18

Rock colorMost mice captured on pale rockshad sandy-colored fur.

Most mice captured on dark rocks had black fur.

Diversity of Life on Earth

Produced by accumulation of adaptations and other genetic differences between populations over long spans of time

1.3 Biodiversity

Species • Closely related populations that can interbreed

Biologists classify organisms into three domains and several kingdoms

Hierarchy of Classification

Species Genus Family Order Class Phylum Kingdom

Classification

Fig. 1-11, p. 10

Fig. 1-11, p. 10

Domain: Eukarya

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Carnivora

Family: Canidae

Genus: Canis

Species: Canis familiaris

Phylum: Chordata

Class: Mammalia

Domain: Eukarya

Kingdom: Animalia

Order: Carnivora

Family: Canidae

Genus: Canis

Species: Canis familiaris

Fig. 1-11, p. 10

Stepped Art

Domains

Biologists organize kingdoms into 3 domains based on characteristics of cell structure • Bacteria

• Archaea

• Eukarya

3 Domains of Life

Fig. 1-13, p. 12

Fig. 1-13, p. 12

a. Domain Bacteria

b. Domain Archaea

c. Domain EukaryaKingdom Protoctista Kingdom Fungi

Kingdom AnimaliaKingdom Plantae

Kingdoms

Bacteria and Archaea each include one kingdom

Eukarya is divided into four kingdoms: • Protoctista

• Plantae

• Fungi

• Animalia

Prokaryotes and Eukaryotes

Fig. 1-12, p. 11

Fig. 1-12a, p. 11

DNA

a. Escherichia coli, a prokaryote

Fig. 1-12b, p. 11

Nucleus with DNA

b. Paramecium aurelia, a eukaryote

1.4 Biological Research

Biologists conduct basic and applied research using the scientific method

Research includes collecting observational and experimental data

Hypotheses may be tested with controlled experiments

Or, a null hypotheses may be used to evaluate observational data

1.4 (cont.)

Model organisms may be used to study fundamental biological processes

Molecular techniques have revolutionized biological research

Scientific theories are ideas that have withstood the test of time

Basic and Applied Research

Basic research advances our knowledge of living systems

Applied research solves practical problems

Data

Observational data describe biological organisms or the details of biological processes

Experimental data describe results of an experimental manipulation

Hypotheses

Working explanations developed by scientists about the relationships between variables

Scientific hypotheses must be falsifiable

Experiment

A well-designed experiment• Considers alternative hypotheses

• Includes control treatments and replicates

Experimental Research

Fig. 1-14, p. 15

Fig. 1-14a (1), p. 15

Fig. 1-14a (2), p. 15

Fig. 1-14b, p. 15

Animation: Life’s diversity

Null Hypotheses

Explanations of what scientists would see if their hypothesis was wrong

Used to evaluate observational or experimental data when experiments are unfeasible

Observational Research

Fig. 1-15de, p. 17

Fig. 1-15a, p. 17

Anolis gundlachi

Fig. 1-15b, p. 17

Anolis cristatellus

Fig. 1-15c, p. 17

Copper Anolis model

Fig. 1-15d, p. 17

Percentage of models and lizards perched in sun or shade

In the forest where A. gundlachi lives,nearly all models and nearly all lizards perched in shade.

Per

cen

tag

e in

su

n o

r sh

ade

LizardsModels LizardsModelsPer

cen

tag

e in

su

n o

r sh

ade

Perched in sun

Perched in shade

In the habitat where A. cristatellus lives,nearly all modelsperched in shade, but most lizards perched in sun.

Anolis gundlachi Anolis cristatellus

Fig. 1-15e, p. 17

Temperatures of models and lizards

Lizards

Models

Lizards

Models

Per

cen

tag

e o

f o

bse

rvat

ion

s

Per

cen

tag

e o

f o

bse

rvat

ion

sTemperature (°C) Temperature (°C)

Body temperaturesof A. gundlachi were not significantlydifferent from those of the randomly placed models.

Body temperaturesof A. cristatellus were significantly higher than those of the randomly placed models.

Anolis gundlachi Anolis cristatellus

Animation: Sample size and accuracy

Modern Techniques

Model organisms• Easy to maintain in the laboratory

• Subjects of much research

Molecular techniques• Manipulation of specific genes in the laboratory

• Allow detailed analysis of DNA of many species

A Scientific Theory

A set of broadly applicable hypotheses• Completely supported by repeated tests under

many conditions and different situations

Theory of evolution by natural selection• Explains how life evolved through natural

processes

• Central importance to biology

Animation: How do scientists use random samples to test hypotheses

Video: Bird flu