Chapter 1:

Exploring Life

History is a vital tool in learning about science.

Louis Pastuer Charles Darwin

Figure 1.1

Biology is the science that focuses on life

Figure 1.3

Order

Evolutionary adaptation

Response tothe environment

Reproduction

Growth anddevelopment

Energy processing

Regulation

Exploring Levels of Biological Organization1 The biosphere

2 Ecosystems

3 Communities

4 Populations

5 Organisms

8 Cells

6 Organs and organ systems

7 Tissues

10 Molecules

9 Organelles

50 µm

10 µm

1 µmCell

Atoms

Basic scheme for energy flow through an ecosystem

Figure 1.5Leaves take incarbon dioxide

from the airand release

oxygen.

Animals eatleaves and fruitfrom the tree.

Sunlight

CO2

O2

Cyclingof

chemicalnutrients

Leaves fall tothe ground and

are decomposedby organisms

that returnminerals to the

soil.

Water andminerals inthe soil aretaken up by

the treethroughits roots.

Leaves absorblight energy from

the sun.

Inherited DNA directs development of an organism

Sperm cell

NucleicontainingDNA

Egg cell

Fertilized eggwith DNA fromboth parents

Embyro’s cells with copies of inherited DNA

Offspring with traitsinherited fromboth parents

Figure 1.10

DNA: The genetic materialNucleus

DNA

Cell

Nucleotide

A

C

T

A

T

A

C

C

G

G

T

A

T

A

(b) Single strand of DNA. These geometric shapes and letters are simple symbols for the nucleotides in a small section of one chain of a DNA molecule. Genetic information is encoded in specific sequences of the four types of nucleotides (their names are abbreviated here as A, T, C, and G).

(a) DNA double helix. This model shows each atom in a segment of DNA. Made up of two long chains of building blocks called nucleotides, a DNA molecule takes the three-dimensional form of a double helix.

Contrasting eukaryotic and prokaryotic cells in size and complexity

Figure 1.8

Eukaryotic cellProkaryotic cell

Cytoplasm

DNA(no nucleus)

Membrane

Nucleus(membrane-enclosed)

Membrane

Membrane-enclosed organelles

DNA (throughoutnucleus) 1 m

Modern biology as an information science

Figure 1.13

Negativefeedback

A

B

C

D

C

Enzyme 1

Enzyme 2

Enzyme 3

D

W

Enzyme 4

X

DD

Excess Dblocks a step.

(a) Negative feedback

Positive feedback

Excess Zstimulates a step.

Y

Z

Z

Z

Z

(b) Positive feedback

Enzyme 5

Enzyme 6

Drawers of diversity

Classifying lifeSpecies Genus Family Order Class Phylum Kingdom Domain

Mammalia

Ursusameri-canus(Americanblack bear)

Ursus

Ursidae

Carnivora

Chordata

Animalia

Eukarya

Exploring Life’s Three Domains

(a) Domain Bacteria (b) Domain Archaea

(c) Domain Eukarya

2 m

2 m

100 m

Kingdom Plantae

Kingdom Fungi

Protists

Kingdom Animalia

An example of unity underlying the diversity of life: the architecture of cilia in eukaryotes

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 afilm of debris-trapping mucus upward.

Digging into the past

Charles Darwin in 1859, the year he published The Origin of Species

Unity and diversity in the orchid family

Summary of natural selection

Populationof organisms

Hereditaryvariations

Differences in reproductive success

Evolution of adaptationsin the population

Overproductionand struggle forexistence

Natural selection

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.

Form fits function

Descent with modification: adaptive radiation of finches on the Galápagos Islands

Figure 1.22

COMMONANCESTOR

Green warbler finchCerthidea olivacea

Gray warbler finchCerthidea fusca

Sharp-beakedground finch

Geospiza difficilisVegetarian finch

Platyspiza crassirostris

Mangrove finchCactospiza heliobates

Woodpecker finchCactospiza pallida

Medium tree finchCamarhynchus pauper

Large tree finchCamarhynchus psittacula

Small tree finchCamarhynchus parvulus

Large cactusground finch

Geospiza conirostrisCactus ground finchGeospiza scandens

Small ground finchGeospiza fuliginosa

Medium ground finchGeospiza fortis

Large ground finchGeospiza

magnirostris

Inse

ct-e

aters

See

d-e

ater

Bu

d-e

ate

r

Inse

ct-e

aters

Tree

finc

he

sG

rou

nd

finch

es

See

d-e

aters

Cac

tus

-flow

er-

ea

ters

Warb

ler fin

ch

es

A campground example of hypothesis-based inquiry

Observations

Questions

Hypothesis # 1:Dead batteries

Hypothesis # 2:Burnt-out bulb

Prediction:Replacing batterieswill fix problem

Prediction:Replacing bulbwill fix problem

Test prediction

Test does not falsify hypothesis

Test prediction

Test falsifies hypothesis

Figure 1.23

A stinging honeybee and its nonstinging mimic, a flower fly

Flower fly(non-stinging)

Honeybee (stinging)

Science as a social process

Eleven Themes that Unify Biology