Exploring Life
Chapter 1
Advanced Placement Biology
Liberty Senior High School
Mr. Knowles
Life
• Defies a simple, one-line definition.
• Lends itself to mysticism.
Figure 1.1
What is biology?
Biology
• Bios = Greek for “life”
• Logos = Greek for “study” or
“thought”
• Biology - the study of living
things
• Concept 1.1: Biologists explore life
from the microscopic to the global
scale.
• The study of life:
–Extends from the microscope
scale of molecules and cells to
the global scale of the entire
living planet.
What does it mean to be
alive?
What characteristics define
life?
What are the criteria for
something to be alive?
(b) Evolutionary
adaptation
(a) Order
(c) Response to the
environment
(d) Regulation
(e) Energy
processing
(f) Growth and
development
Figure 1.2
(g) Reproduction
What does it mean to be
“living?”
Some Characteristics:
1. Order- have a hierarchical
organization (Fig 1.3).
A Hierarchy of Biological
Organization
• The hierarchy of life
–Extends through many levels of
biological organization
• From
the
biosphere
to
organisms…
1 The biosphere
1.a. biome
2. Ecosystems
3. Communities
4. Populations
Figure
1.3
5. Organisms
• From cells to atoms.
9 Organelles
1 µm
Cell
8 Cells
Atoms
10 µm
7 Tissues
50 µm
6 Organs and organ systems
Figure 1.3
10 Molecules
Order Beyond the Organism
• Population- a group of individuals
of same species occupying a given
area at the same time.
• Community- a number of
interacting populations in a
common environment.
Order in Biology
• Ecosystem- organisms (biotic)
interacting with their nonliving
(abiotic) environment.
• Biomes- major groupings of plants,
animals, and microorganisms that
occur over a wide geography and
have distinct characteristics (ex.
deserts, tropical rainforests)
The Emergent Properties of
Systems
• Biological systems are much more
than the sum of their parts.
• Due to increasing complexity
–New properties emerge with each
step upward in the hierarchy of
biological order
What does it mean to be
“living?”
2. Responsiveness or Sensitivityhave a response to stimuli.
• Chemotactic
• Phototactic
• Thigmotropic
• Gravitropic
Is fire alive?
A Closer Look at Cells
• The cell
– Is the lowest level of organization that can
perform all activities required for life
Figure 1.5
25 µm
The Cell’s Heritable Information
• Cells contain chromosomes made partly of
DNA, the substance of genes
– Which program the cells’ production of
proteins and transmit information from parents
to offspring
Sperm cell
Nuclei
containing
DNA
Egg cell
Figure 1.6
Fertilized egg
with DNA from
both parents
Embyro’s cells
with copies of
inherited DNA
Offspring with traits
inherited from
both parents
• The molecular structure of DNA
– Accounts for it information-rich nature.
Nucleus
DNA
Cell
A
Nucleotide
C
T
A
T
A
C
C
G
T
A
G
T
A
Figure 1.7
(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).
What does it mean to be
“living?”
3. Growth, Development,
and Reproduction- all use
hereditary molecules to pass
genetic information to
offspring.
Two Main Forms of Cells
• All cells share certain characteristics
–They are all enclosed by a membrane
–They all use DNA as genetic
information
• There are two main forms of cells:
–Eukaryotic
–Prokaryotic
• Prokaryotic cells
– Lack the kinds of membrane-enclosed
organelles found in eukaryotic cells.
EUKARYOTIC CELL
PROKARYOTIC CELL
DNA
(no nucleus)
Membrane
Membrane
Cytoplasm
Organelles
Figure 1.8
Nucleus (contains DNA)
1 µm
What does it mean to be
“living?”
4. Regulation- have regulatory
mechanisms to coordinate
functions (transportation of
nutrients, wastes, etc.); maintain
homeostasis.
Feedback Regulation in Biological
Systems
• A kind of supply-and-demand
economy:
–Applies to some of the dynamics of
biological systems.
–The output, or product, of a process
regulates that very process feedback regulation.
• In negative feedback:
– An accumulation of an end product slows
the process that produces that product.
A
Negative
feedback
Enzyme 1
B
A
Enzyme 1
B
Enzyme 2
C
C
Enzyme 3
D
D
Figure 1.11
D
D
D
D
D
D
D
D
D
• In positive feedback:
–The end product speeds up production.
W
W
Enzyme 4
Enzyme 4
X
Positive
feedback
X
Enzyme 5
Enzyme 5
Y
Y
Enzyme 6
Z
Z
Z
Z
Z
Z
Z
Z
Figure 1.12
Enzyme 6
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Question: Are viruses
alive?
Grouping Species: The Basic
Idea
• Diversity is a hallmark of life.
• Taxonomy:
–is the branch of biology that
names and classifies species
according to a system of broader
and broader groups
• Classifying life
Species
Genus
Family
Order
Class
Phylum
Ursus
americanus
(American
black bear)
Ursus
Ursidae
Carnivora
Mammalia
Chordata
Animalia
Figure 1.14
Eukarya
Kingdom
Domain
The Three Domains of Life
• At the highest level, life is classified into three
domains:
– Bacteria
– Archaea
– Eukarya
• Domain Bacteria and domain Archaea
– Consist of prokaryotes
• Domain Eukarya, the eukaryotes
– Includes the various protist kingdoms and the
kingdoms Plantae, Fungi, and Animalia
• Life’s three domains
4 µm
Bacteria are the most diverse
and widespread prokaryotes
and are now divided among multiple
kingdoms. Each of the rod-shaped
structures in this photo is a bacterial cell.
DOMAIN ARCHAEA
Figure 1.15
Many of the prokaryotes known
0.5 µm
as archaea live in Earth‘s
extreme environments, such as salty lakes
and boiling hot springs. Domain Archaea
includes multiple kingdoms. The photo
shows a colony composed of many cells.
Kingdom Plantae consists of
100 µm
Protists (multiple kingdoms)
multicellula eukaryotes that carry
are unicellular eukaryotes and
out photosynthesis, the conversion
their relatively simple multicellular relatives.Pictured
of light energy to food.
here is an assortment of protists inhabiting pond water.
Scientists are currently debating how to split the protists
into several kingdoms that better represent evolution
and diversity.
Kindom Fungi is defined in part by the
nutritional mode of its members, such
as this mushroom, which absorb
nutrientsafter decomposing organic
material.
Kindom Animalia consists of
multicellular eukaryotes that
ingest other organisms.
Unity in the Diversity of Life
• As diverse as life is
– There is also evidence of remarkable unity
15 µm
1.0 µm
Cilia of Paramecium.
The cilia of Paramecium
propel the cell through
pond water.
5 µm
Figure 1.16
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.
• Concept 1.4: Evolution accounts for life’s
unity and diversity
• The history of life
– Is a saga of a changing Earth billions of years old
Figure 1.17
Theodosius Dobzhansky
“Nothing in biology makes sense
except in the light of
evolution.”
The American Biology Teacher (1973)
• The evolutionary view of life…
– Came into sharp focus in 1859 when Charles
Darwin published On the Origin of Species by
Means of Natural Selection
Figure 1.18
• The Origin of Species articulated two
main points…
– Descent with modification
– Natural selection
Figure 1.19
Natural Selection
• Darwin proposed natural selection
– As the mechanism for evolutionary adaptation
of populations to their environments
Population
of organisms
Hereditary
variations
Overproduction
and struggle for
existence
Differences in reproductive
success
Figure 1.20
Evolution of adaptations
in the population
• Natural selection is the evolutionary process that
occurs…
– When a population’s heritable variations are exposed
to environmental factors that favor the reproductive
success of some individuals over others.
1
Populations with varied inherited traits
2 Elimination of individuals with certain traits.
3 Reproduction of survivors.
Figure 1.21
4 Increasing frequency of traits that enhance
survival and reproductive success.
Darwin, 1835, Galapagos
• Darwin proposed that natural selection
– Could enable an ancestral species to “split”
into two or more descendant species,
resulting in a “tree of life”
Large
ground finch
Large cactus
ground finch
Small
ground
finch
Large
tree finch
Camarhynchus
Green
Geospiza
Gray
Geospiza
magnirostris
psitacula
warbler
warbler
Sharp-beaked
fuliginosa
Woodpecker Medium
Geospiza Medium
finch
finch
tree finch
ground finch
finch
conirostris ground
finch
Certhidea Certhidea
Geospiza Cactus
Cactospiza Camarhynchus olivacea fusca
difficilis ground finch
pauper
pallida
Geospiza Mangrove
Small tree finch
finch
fortis
Geospiza
Camarhynchus
Cactospiza
scandens
parvulus
heliobates
Vegetarian
Cactus flower
Seed eater
Seed eater
finch
eater
Platyspiza
crassirostris
Insect eaters
Ground finches
Figure 1.23
Tree finches
Bud eater
Warbler finches
Common ancestor from
South American mainland
Large
ground finch
Large cactus
ground finch
Geospiza
magnirostris
Geospiza
conirostris
Woodpecker
finch
Medium
ground
finch
Cactus
ground finch
Cactospiza
pallida
Geospiza
fortis
Geospiza
scandens
Seed eater
Camarhynchus
psitacula
Geospiza
fuliginosa
Sharp-beaked
ground finch
Geospiza
difficilis
Large
tree finch
Small
ground
finch
Cactus flower
eater
Green
warbler
finch
Medium
tree finch
Certhidea
olivacea
Camarhynchus
pauper
Mangrove
finch
Gray
warbler
finch
Certhidea
fusca
Small tree finch
Camarhynchus
parvulus
Cactospiza
heliobates
Vegetarian
finch
Seed eater
Platyspiza
crassirostris
Insect eaters
Ground finches
Figure 1.23
Tree finches
Bud eater
Warbler finches
Common ancestor from
South American mainland
Concept 1.5: Biologists use various
forms of inquiry to explore life
• At the heart of science is inquiry
–A search for information and
explanation, often focusing on specific
questions
• Biology blends two main processes of
scientific inquiry
–Discovery science
–Hypothesis-based science
Discovery Science
• Discovery Science:
–Describes natural structures
and processes as accurately as
possible through careful
observation and analysis of
data.
Types of Data
• Data:
–Are recorded observations.
–Can be quantitative or qualitative.
Figure 1.24
Induction in Discovery Science
• In inductive reasoning:
–Scientists derive generalizations
based on a large number of
specific observations. Ex. Cell
Theory- “All organisms are made
of cells”; specific observations
one generalization
Hypothesis-Based Science
• In science, inquiry that asks
specific questions:
–Usually involves the proposing
and testing of hypothetical
explanations, or hypotheses.
Deduction: The “If…then” Logic of
Hypothesis-Based Science
• In deductive reasoning:
–The logic flows from the general to
the specific. Ex. “If all organisms are
made of cells and humans are
organisms, then humans are
composed of cells.”
• Makes a deductive prediction; general
to the specific
The Scientific MethodAway of Looking at Life!
Click for the
Method
A Biological Example of a
Theory
How can living things
change over time?
Why do male and female
lions look different?
• Concept 1.6: A set of themes
connects the concepts of biology
Underlying themes
–Provide a framework for
understanding biology
Eleven themes that unify biology
Table 1.1
•
•
•
•
•
•
•
•
Common Themes in Biology
Science as a Process
Evolution
Energy Transfer
Continuity and Change
Relationship of Structure and Function
Regulation
Interdependence in Nature
Science, Technology, and Society
How many moths do you see?