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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
Response to
the environment
Evolutionary adaptation
Reproduction
Regulation
Energy processing
Growth and
development
Exploring Levels of Biological Organization
1 The biosphere
2 Ecosystems
3 Communities
4 Populations
5 Organisms
9 Organelles
1 µm
Cell
8 Cells
Atoms
10 µm
7 Tissues
50 µm
6 Organs and organ systems
10 Molecules
Basic scheme for energy flow through an ecosystem
Sunlight
Figure 1.5
Leaves absorb
light energy from
the sun.
CO2
Leaves take in
carbon dioxide
from the air
and release
oxygen.
O2
Cycling
of
chemical
nutrients
Leaves fall to
the ground and
are decomposed
by organisms
that return
minerals to the
soil.
Water and
minerals in
the soil are
taken up by
the tree
through
its roots.
Animals eat
leaves and fruit
from the tree.
Inherited DNA directs development
of an organism
Figure 1.10
Sperm cell
Nuclei
containing
DNA
Egg cell
Fertilized egg
with DNA from
both parents
Embyro’s cells
with copies of
inherited DNA
Offspring with traits
inherited from
both parents
DNA: The genetic material
Nucleus
DNA
Cell
A
C
Nucleotide
T
A
T
A
C
C
G
T
A
G
T
A
(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.
(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).
Contrasting eukaryotic and prokaryotic cells in
size and complexity
Prokaryotic cell
Eukaryotic cell
Membrane
Figure 1.8
Cytoplasm
Membraneenclosed organelles
DNA
(no nucleus)
Membrane
Nucleus
(membraneenclosed)
DNA (throughout
1 m
nucleus)
Modern biology as an information science
Figure 1.13
Negative
feedback
A
Enzyme 1
B
Excess D
blocks a step.
D
D
Enzyme 2
D
C
Enzyme 3
D
(a) Negative feedback
W
Enzyme 4
Positive
feedback 
X
Enzyme 5
Excess Z
stimulates a
step.
Z
Y
Z
Z
Enzyme 6
Z
(b) Positive feedback
Drawers of diversity
Classifying life
Species Genus Family
Order
Class
Phylum
Ursus
americanus
(American
black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Eukarya
Kingdom
Domain
Exploring Life’s Three Domains
2 m
(b) Domain Archaea
2 m
(a) Domain Bacteria
(c) Domain Eukarya
Kingdom Animalia
100 m
Kingdom Plantae
Protists
Kingdom Fungi
An example of unity underlying the diversity of life: the
architecture of cilia in eukaryotes
15 µm
1.0 µm
Cilia of Paramecium.
The cilia of Paramecium
propel the cell through
pond water.
5 µm
Cross section of cilium, as viewed
with an electron microscope
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.
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
Population
of organisms
Hereditary
variations
Overproduction
and struggle for
existence
Differences in
reproductive success
Evolution of adaptations
in the population
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
Insect-eaters
Gray warbler finch
Certhidea fusca
Bud-eater
Seed-eater
Warbler finches
COMMON
ANCESTOR
Green warbler finch
Certhidea olivacea
Sharp-beaked
ground finch
Geospiza difficilis
Vegetarian finch
Platyspiza crassirostris
Mangrove finch
Cactospiza heliobates
Insect-eaters
Tree finches
Woodpecker finch
Cactospiza pallida
Medium tree finch
Camarhynchus pauper
Large tree finch
Camarhynchus psittacula
Figure 1.22
Small tree finch
Camarhynchus parvulus
Cactus-flowereaters
Seed-eaters
Ground finches
Large cactus
ground finch
Geospiza conirostris
Cactus ground finch
Geospiza scandens
Small ground finch
Geospiza fuliginosa
Medium ground finch
Geospiza fortis
Large ground finch
Geospiza
magnirostris
A campground example of hypothesis-based
inquiry
Observations
Questions
Hypothesis # 1:
Dead batteries
Hypothesis # 2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test falsifies hypothesis
Test prediction
Test does not falsify 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