Eldra Solomon
Linda Berg
Diana W. Martin
www.cengage.com/biology/solomon
Chapter 1
A View of Life
Albia Dugger • Miami Dade College
A View of Life: H1N1
H1N1
• H1N1 influenza attracted global attention in April 2009, when
more than 200 countries around the world reported confirmed
cases within a few months
• Pandemics such as H1N1 affect many aspects of life,
including global economy, travel, tourism, and education
Biology
• Biologists are making new discoveries that affect every
aspect of our lives, including health, food, safety, relationships
with humans and other organisms, and the environment of
our planet
• biology
• The science of life
1.1 THREE BASIC THEMES
LEARNING OBJECTIVE:
• Describe three basic themes of biology
Three Basic Themes of Biology
• Evolution
• Evolution results in populations changing over time
• Explains how the ancestry of organisms can be traced
back to earlier forms of life
• Information transfer
• Information must be transmitted within cells, among cells,
among organisms, and from one generation to the next
• Energy transfer
• Life requires continuous input of energy from the sun
KEY CONCEPTS 1.1
• Basic themes of biology include evolution, information
transfer, and energy transfer
1.2 CHARACTERISTICS OF LIFE
LEARNING OBJECTIVE:
• Distinguish between living and nonliving things by
describing the features that characterize living organisms
Organisms are Composed of Cells
• cell theory
• A fundamental unifying concept of biology
• Every living organism is composed of one or more cells
• New cells are formed only by division of previously
existing cells
• Simple, unicellular life-forms consist of a single cell
• Complex, multicellular organisms depend on coordinated
functions of cells that are organized to form tissues, organs,
and organ systems
Unicellular and Multicellular Life-Forms
• Paramecium
(a) Unicellular organisms consist of one intricate
cell that performs all the functions essential to
life. Ciliates, such as this Paramecium , move
about by beating their hairlike cilia.
• African buffalo, plants
(b) Multicellular organisms, such as this African
buffalo (Syncerus caffer) and the plants on
which it grazes, may consist of billions of cells
specialized to perform specific functions.
Cell Structure
• A plasma membrane protects the cell and regulates passage
of materials between the cell and its environment
• Specialized molecules – usually deoxyribonucleic acid (DNA)
– contain genetic instructions and transmit genetic information
• Internal structures (organelles) are specialized to perform
specific functions
Two Types of Cells
• prokaryotic cells
• Exclusive to bacteria and archaea
• Structurally simple; they do not have a nucleus or other
membrane-enclosed organelles
• eukaryotic cells
• Typically contain a variety of organelles enclosed by
membranes, including a nucleus, which houses DNA
Organisms Grow and Develop
• Biological growth involves an increase in size of individual
cells of an organism, in number of cells, or in both
• Some organisms (e.g. trees) grow throughout their lives
• Many animals have a growth period that ends at adult size
• Development includes all changes during an organism’s life
• Example: A human develops from a fertilized egg into a
multicellular organism with structures and body form
adapted to specific functions
Organisms Regulate
Their Metabolic Processes
• Metabolism includes all chemical activities that take place in
an organism, including chemical reactions essential to
nutrition, growth and repair, and conversion of energy
• Homeostatic mechanisms carefully regulate metabolic
processes to maintain an appropriate, balanced internal
environment (homeostasis)
• Example: Regulation of blood sugar (glucose)
Organisms Respond to Stimuli
• Organisms respond to physical or chemical changes in their
external or internal environment (stimuli)
• Responses typically involve movement
• Unicellular organisms may move by slow oozing of the cell
(amoeboid movement), by beating tiny, hairlike extensions of
the cell (cilia) or longer structures (flagella)
Flagella
• Bacteria equipped
with flagella for
locomotion
• Helicobacter pylori
have been linked to
stomach ulcers
Organisms Respond to Stimuli (cont.)
• Most animals move by contracting muscles
• Complex animals have highly specialized cells that respond to
specific types of stimuli, such as light
• Plants respond to light, gravity, water, touch, and other stimuli
Plants Respond to Stimuli
Fig. 1-3a, p. 4
Organisms Reproduce
• asexual reproduction
• Offspring have the same genes as the single parent
• Variation occurs only by mutations
• sexual reproduction
• Offspring are produced by fusion of egg and sperm
• Genes are typically contributed by two parents
Asexual and Sexual Reproduction
Fig. 1-4, p. 5
Populations Evolve and Become
Adapted to the Environment
• As populations evolve, they become adapted to their
environment
• Adaptations may be structural, physiological, biochemical,
behavioral, or a combination of all four
• adaptations
• Inherited characteristics that enhance an organism’s ability
to survive in a particular environment
Adaptations
• Burchell’s zebras (1) are behaviorally adapted to watch for
predators, (2) have stripes for visual protection against
predators, (3) have stomachs adapted to coarse grass
(enlarged cecum)
Fig. 1-5, p. 5
KEY CONCEPTS 1.2
• Characteristics of life include:
• cellular structure
• growth and development
• self-regulated metabolism
• response to stimuli
• reproduction
1.3 LEVELS OF
BIOLOGICAL ORGANIZATION
LEARNING OBJECTIVE:
• Construct a hierarchy of biological organization,
including levels characteristic of individual organisms
and levels characteristic of ecological systems
Organisms Have Several
Levels of Organization
• Atoms and molecules form cells
• Cells associate to form tissues
• Tissues organize into functional structures (organs)
• In animals, major biological functions are performed by a
coordinated group of tissues and organs (organ system)
• Organ systems function together to make up a complex,
multicellular organism
Several Levels of Ecological
Organization Can Be Identified
• population
• All members of one species living in the same geographic
area at the same time
• community
• Populations of various types of organisms living and
interacting with one another in a particular area
• ecosystem
• A community together with its nonliving environment
Levels of Organization (cont.)
• All of Earth’s ecosystems together are known as the
biosphere
• The study of how organisms relate to one another and to their
physical environment is called ecology
Hierarchy of Biological Organization
Organism
Organ systems work
together in a
functional organism.
Organ system
(e.g., skeletal system)
Tissues and organs make
up organ systems.
Population
A population consists
of organisms of the
same species.
Organism
Population
Organ
system
Organ
(e. g., bone) Tissues
form organs.
Community
The populations of
different species that
populate the same area
make up a community.
Organ
Tissue
(e.g., bone tissue) Cells
associate to form tissues.
Cellular level
Atoms and molecules make
up the cytoplasm and form
organelles, such as the
nucleus and mitochondria
(the site of many energy
transformations). Organelles
perform various functions
of the cell.
Chemical level
Atoms join to form
molecules. Macromolecules
are large molecules such
as proteins and DNA.
Community
Tissue
Bone cells
Nucleus
Cell
Organelle
Ecosystem
Macromolecule
Biosphere
Molecule
Oxygen atom
Hydrogen atoms
Water
Ecosystem
A community together
with the nonliving
environment forms
an ecosystem.
Biosphere
Earth and all of its
communities constitute
the biosphere.
Stepped Art
Fig. 1-6, p. 7
KEY CONCEPTS 1.3
• Biological organization includes chemical, cell, tissue, organ,
organ system, and organism levels
• Ecological organization includes population, community,
ecosystem, and biosphere levels
1.4 INFORMATION TRANSFER
LEARNING OBJECTIVE:
• Summarize the importance of information transfer within
and between living systems, giving specific examples
DNA Transmits Information from
One Generation to the Next
• A DNA molecule consists of two chains of atoms twisted into
a helix
• Each chain is made up of a sequence of chemical subunits
called nucleotides
DNA
• DNA is the hereditary
material that transmits
information from one
generation to the next
• The sequence of
nucleotides makes up
the genetic code
Fig. 1-7, p. 8
Information is Transmitted by
Chemical and Electrical Signals
• Genes control development and function of every organism
• The DNA that makes up genes contains instructions for
making all the proteins required by the organism
• proteins
• Large molecules important in determining the structure
and function of cells and tissues
Communication Between Cells
• Cells use proteins and other molecules to communicate with
one another
• Hormones and other chemical messengers signal cells in
distant organs to secrete a required substance or change a
metabolic activity
• Animals’ nervous systems transmit information by electrical
impulses and chemical compounds (neurotransmitters)
KEY CONCEPTS 1.4
• Information transfer includes:
• DNA transfer of information from one generation to the
next
• Chemical and electrical signals within and among the cells
of every organism
• Chemicals, visual displays, and sounds that allow
organisms to communicate with one another and to
interact with their environment
1.5 THE ENERGY OF LIFE
LEARNING OBJECTIVE:
• Summarize the flow of energy through ecosystems and
contrast the roles of producers, consumers, and
decomposers
Energy and Metabolism
• Life depends on continuous input of energy from the sun
• Whenever energy is used to perform biological work, some is
converted to heat and dispersed into the environment
• All energy transformations and chemical processes within an
organism are referred to as its metabolism
Cellular Respiration
• All cells require nutrients that contain energy
• During cellular respiration, cells capture energy released by
nutrient molecules through a series of carefully regulated
chemical reactions
• Cells use this energy to do work, including synthesis of new
cell components
Energy in Ecosystems
• Ecosystems also depend on continuous energy input
• Ecosystems include three types of organisms (producers,
consumers, decomposers) and their physical environment
• There is a one-way flow of energy through ecosystems
• Organisms can neither create energy nor use it with
complete efficiency
• During every energy transaction, some energy disperses
into the environment as heat
The Producers
• Plants, algae, and some bacteria are producers (autotrophs)
that produce their own food from simple raw materials
• Most producers use sunlight as energy for photosynthesis,
which transforms light energy into chemical energy stored in
chemical bonds of food molecules
• Photosynthesis synthesizes food molecules such as glucose
(sugar) from carbon dioxide and water, and releases oxygen:
carbon dioxide + water + light → glucose + oxygen
The Consumers
• Animals are consumers (heterotrophs) that obtain energy
by breaking down food molecules produced in photosynthesis
• Primary consumers eat producers; secondary consumers
eat primary consumers
• Chemical bonds are broken in the process of cellular
respiration, and stored energy is made available:
glucose + oxygen → carbon dioxide + water + energy
The Decomposers
• Most bacteria and fungi are decomposers, heterotrophs that
obtain nutrients by breaking down nonliving organic material
such as wastes, dead leaves and branches, and bodies of
dead organisms
• In the process of obtaining energy, decomposers make the
components of these materials available for reuse
Energy Flow Within
and Among Organisms
Light
energy
Photosynthesis
captures light
energy
Oxygen
Energy stored in
glucose and other
nutrients
Carbon
dioxide and
water
Oxygen
Energy
Cellular respiration
releases energy
stored in glucose
molecules
Synthesis of Other Life Activities
needed
• Homeostasis
• Growth and
molecules
and structures development
• Reproduction
• Movement of materials
in and out of cells
• Movement of body
Fig. 1-8, p. 9
Energy Flow Through the Biosphere
• During every energy
transaction, some
energy is lost to
biological systems,
dispersing into the
environment as heat
Light
energy
Heat
Heat
Food
Heat
Primary
consumer
(caterpillar)
Secondary
consumer
(robin)
Heat
Producer
(plant)
Plant litter,
wastes
Soil
Dead
bodies
Decomposers
(bacteria, fungi)
Fig. 1-9, p. 10
1.6 THE BASIC CONCEPTS OF BIOLOGY
LEARNING OBJECTIVES:
• Demonstrate the binomial system of nomenclature using
specific examples, and classify an organism in its domain,
kingdom, phylum, class, order, family, genus, and species
• Identify the three domains and the kingdoms of living
organisms, and give examples of organisms in each group
• Give a brief overview of the scientific theory of evolution and
explain why it is the principal unifying concept in biology
• Apply the theory of natural selection to any given adaptation
and suggest a logical explanation of how it may have evolved
Evolution
• evolution
• Process by which populations of organisms change over
time
• Involves passing genes for new traits from one generation
to another, leading to differences in populations
Biologists Use a Binomial System
for Naming Organisms
• Systematics is the field of biology that studies the diversity of
organisms and their relationships
• Taxonomy, is the science of naming and classifying
organisms
Binomial System
• The binomial system of nomenclature is used to name
each species, it is called such because each species has a
two-part name
• The first part of the name is the genus
• The second part, the specific epithet, designates a particular
species in that genus
• Example: The domestic dog, Canis familiaris (or C. familiaris),
and timber wolf, Canis lupus (C. lupus), are in the same
genus
Species and Genus
• A species is a group of organisms with similar structure,
function, and behavior
• Closely related species are grouped into a genus (genera)
Taxonomic Classification
is Hierarchical
• Related genera are grouped in a family
• Families are grouped into orders, orders into classes, and
classes into phyla (phylum)
• Phyla are assigned to kingdoms, and kingdoms are grouped
in domains
• Each level is a taxon (taxa)
Classification of the Cat, Human,
and White Oak Tree
Table 1-1, p. 11
DOMAIN
Eukarya
KINGDOM
Animalia
PHYLUM
Chordata
CLASS
Mammalia
ORDER
Primates
FAMILY
Pongidae
GENUS
Pan
SPECIES
Pan troglodytes
Fig. 1-10, p. 12
Three Domains
• Most biologists assign organisms to three domains and
several kingdoms
• There are two domains of organisms with prokaryotic cells
(prokaryotes): Bacteria and Archaea
• Kingdom Archaea corresponds to domain Archaea
• Kingdom Bacteria corresponds to domain Bacteria
• All other organisms belong to the domain Eukarya
Domain Eukarya
• Organisms with eukaryotic cells (eukaryotes) are classified in
domain Eukarya
• Protists (including five “supergroups”) are unicellular,
colonial, or simple multicellular eukaryotic organisms
• Kingdom Plantae (plants) are complex multicellular
organisms adapted for photosynthesis
• Kingdom Fungi (yeasts, mildews, molds, and mushrooms)
do not photosynthesize – they obtain nutrients by
secreting digestive enzymes into food and absorbing it
• Kingdom Animalia includes complex multicellular
organisms that obtain nutrition by eating other organisms
Three Domains of Life
Domain Bacteria
Domain Archaea
(a) The large,
rod-shaped
bacterium Bacillus
anthracis, a
member of domain
Bacteria, causes
anthrax, a disease
of cattle and sheep
that can infect
humans.
(b) These
archaea
(Methanosarcina
mazei), members
of the domain
Archaea, produce
methane.
Bacteria
Archaea
Domain Eukarya
(c) These
unicellular
protozoa
(Tetrahymena)
are classified in
one of the
protist groups.
Protists
Common ancestor
of all organisms
(d) Plants
include many
beautiful and
diverse forms,
such as the
lady’s slipper
(Phragmipedium
caricinum).
(e) Among the
fiercest animals,
lions (Panthera
leo) are also
among the
most sociable.
The largest of the
big cats, lions live
in prides (groups).
Plants Animals
(f) Mushrooms,
such as these
fly agaric
mushrooms
(Amanita
muscaria), are
fungi. The fly
agaric is
poisonous and
causes delirium,
raving, and
profuse sweating
when ingested.
Fungi
Stepped Art
Fig. 1-11, p. 13
Species Adapt in Response to
Changes in Their Environment
• Every organism is the product of numerous interactions
between environmental conditions and genes inherited from
its ancestors
• If all individuals of a species were exactly alike, any change in
the environment might be disastrous to all, and the species
would become extinct
• Adaptations to changes in the environment occur as a result
of evolutionary processes that take place over time and
involve many generations
Natural Selection:
An Important Evolutionary Mechanism
• Charles Darwin and Alfred Wallace proposed a theory of
evolution and suggested a mechanism: natural selection
• Darwin’s book, On the Origin of Species by Natural Selection
(1859), supported his hypothesis that present forms of life
descended, with modifications, from previously existing forms
Darwin’s Four Observations
• Darwin based his theory on four observations:
1. Individual members of a species vary from one another
2. Organisms produce many more offspring than will survive
to reproduce
3. More individuals are produced than the environment can
support, so organisms must compete for necessary, but
limited, resources; also, some are killed by predators,
disease organisms, or unfavorable natural conditions
4. Individuals with characteristics that enable them to
withstand prevailing environmental conditions and
challenges are more likely to survive and reproduce
Adaptation
• Survivors that reproduce pass their adaptations for survival on
to their offspring
• The best-adapted individuals leave, on average, more
offspring than other individuals (differential reproduction)
• The environment selects the best-adapted organisms of a
population for survival
• Adaptation involves changes in populations, not individuals
Mutation and Variation
• Most variations among individuals result from different
varieties of genes that code for each characteristic
• The ultimate source of these variations is random mutations
(chemical or physical changes in DNA that can be inherited)
• Mutations modify genes and provide the raw material for
evolution
Populations Evolve Due to Selective Pressures
from Environmental Changes
• All genes in a population make up its gene pool (a reservoir
of genetic variation)
• Natural selection acts on individuals within a population
• Selection favors individuals with genes for traits that allow
them to respond effectively to environmental pressure; these
individuals are most likely to survive and produce offspring
• Over time, members of a population become better adapted
to their environment and less like their ancestors – new
species may evolve
1.7 THE PROCESS OF SCIENCE
LEARNING OBJECTIVES:
• Design a study to test a given hypothesis, using the
procedure and terminology of the scientific method
• Compare the reductionist and systems approaches to
biological research
Process of Science
• Science is a way of thinking, and a method of investigating,
the natural world in a systematic manner
• The process of science is investigative, dynamic, and often
controversial – observations, questions, and experimental
design depend on the creativity of the individual scientist
• Science is influenced by cultural, social, historical, and
technological contexts, so the process changes over time
Scientific Method
• The scientific method involves a series of ordered steps:
• Make careful observations
• Ask critical questions and develop hypotheses
• Make predictions that can be tested by making further
observations or by performing experiments
• Gather information (data) that can be analyzed
• Interpret the results of experiments and draw conclusions
Careful Observations and Chance
• 1928: Alexander Fleming did not set out to discover penicillin
• When a blue mold invaded one of his bacterial cultures, he
noticed that the contaminated area was surrounded by a zone
where bacterial colonies did not grow
• Fleming benefited from chance, but his mind was prepared to
make observations and formulate critical questions
A Hypothesis is a Testable Statement
• A hypothesis is a tentative explanation for observations or
phenomena
• A good hypothesis has three characteristics:
1. It is reasonably consistent with well-established facts
2. It is capable of being tested; and test results should be
repeatable by independent observers
3. It is falsifiable (can be proven false)
A Falsifiable Hypothesis Can Be Tested
• A well-stated hypothesis can be tested
• If no evidence is found to support it, the hypothesis is
rejected
• The hypothesis can be shown to be false
• A hypothesis can be supported by data, but it can’t really be
proven true
Models Are Important in
Developing and Testing Hypotheses
• Hypotheses may be derived from models that scientists
develop to provide a comprehensive explanation for a large
number of observations
• Examples: Model of the structure of DNA; model of the
structure of the plasma membrane
• The best design for an experiment can sometimes be
established by performing computer simulations
Many Predictions can
be Tested by Experiment
• Scientists make predictions (deductive, logical
consequences of a hypothesis) that can be tested by
experiments
• Some predictions can be tested by controlled experiments in
which an experimental group differs from a control group
only with respect to the variable being studied
Key Experiment
• Scientists observed that the nucleus was the most prominent
part of the cell, and predicted that cells would be adversely
affected if they lost their nuclei
• Experiment:
• Experimental group: Nucleus was removed
• Control group: A microloop was inserted into the cell to
simulate removal, but the nucleus was left inside
• Result: The control group lived; the experimental group died
Key Experiment (cont.)
Amoeba
dies
(a) Experimental group. When its nucleus is surgically
removed with a microloop, the amoeba dies.
Fig. 1-17a, p. 18
Amoeba
lives
(b) Control group. A control amoeba subjected to similar
surgical procedures (including insertion of a microloop),
but without actual removal of the nucleus, does not die.
Fig. 1-17b, p. 18
Researchers Must Avoid Bias
• In scientific studies, researchers must try to avoid bias or
preconceived ideas of what should happen
• In a double-blind study neither patient nor physician knows
who gets an experimental drug and who gets a placebo
• Not all experiments can be so neatly designed – it is often
difficult to establish appropriate controls
Scientists Interpret Results
and Make Conclusions
• Scientists gather data in an experiment, interpret results, and
draw conclusions from them
• In the amoeba experiment, investigators concluded that data
supported the hypothesis that the nucleus is essential for the
survival of the cell
• Results that falsify a hypothesis also may be valuable and
may lead to new hypotheses
Sampling Error and Repeatability
• One reason for inaccurate conclusions is sampling error
• Not all cases can be observed or tested
• If the sample is too small, it may not be representative
because of random factors
• Scientists try to state that any specific conclusion has a
certain statistical probability of being correct
• Experiments must be repeatable by other scientists
Statistical Probability
Fig. 1-19, p. 21
Curtain
Marbles
Single selection
produces
Assumption
100% blue
Actual ratio
20% blue
80% white
(a) Taking a single selection can result in sampling error. If the only marble
selected is blue, we might assume all the marbles are blue.
Fig. 1-19a, p. 21
Curtain
Marbles
Multiple selections
produce
Assumption
30% blue
Actual ratio
70% white
20% blue
80% white
(b) The greater the number of selections we take of an unknown,
the more likely we can make valid assumptions about it.
Fig. 1-19b, p. 21
A Theory is Supported
by Tested Hypotheses
• A scientific theory is an integrated explanation of some
aspect of the natural world, based on a number of
hypotheses, each supported by consistent results from many
observations or experiments
• By showing relationships among classes of facts, a scientific
theory clarifies our understanding of the natural world
Paradigm Shifts Allow New Discoveries
• A paradigm is a set of assumptions or concepts that
constitute a way of thinking about reality
• As new facts are discovered, biologists have to make
paradigm shifts – they change their view of reality to
accommodate new knowledge
• Systems biology is a field of biology that builds on
information provided and integrates the different levels of
information
Science Has Ethical Dimensions
• Honesty is particularly important in science – science tends to
correct itself through consistent use of the scientific process
• Scientists face many societal and political issues surrounding
areas such as genetic research, stem cell research, cloning,
and human and animal experimentation
• Human genome research raises ethical concerns about the
privacy of genetic information; and the ethical, legal, and
social implications of its findings
KEY CONCEPTS 1.7
• Biologists ask questions, develop hypotheses, make
predictions, and collect data by careful observation and
experiment
• Based on their results, they come to conclusions