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Chapter 1 Outline
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Section 1.1 Outline
• 1.1 How Do Scientists Study Life?
– Life Can Be Studied at ______________
________________
– Scientific ________ Underlie All Scientific Inquiry
– The Scientific _______is the Basis for Scientific
Inquiry
– Communication Is Crucial to Science
– Science is a Human Endeavor
– Scientific Theories Have Been Thoroughly
Tested
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1.2
1.3
1.4
1.5
Biologists and Life
Evolution
“Living Things”
Life Diversity and Classification
Knowledge of Biology and Everyday Life
Levels of Organization
• The living and nonliving world is organized
at many levels
Levels of Organization
• All matter is formed of elements
• An atom is the smallest particle of an
element retaining the properties of an
element
• Atoms combine to form molecules
• Molecules provide the building blocks for
cells, the smallest unit of life
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Levels of Organization
• Some forms of life consist of single cells
• In multicellular forms cells combine to form
tissues
• Tissues combine to form organs, which
can be united as organ systems
• Multicellular organisms are composed of
multiple organ systems
Levels of Organization
• Organisms of the same type that are capable of
interbreeding are called a species
• A group of organisms of the same species living
in a given area is a population
• Interacting populations make up a community
• A community and its nonliving environment is an
ecosystem
• The entire surface of the Earth, including living
and nonliving components is the biosphere
Scientific Principles
• Biology is a scientific discipline
• All scientific inquiry is based on a small set
of assumptions or principles
– Natural causality
– Uniformity in space and time
– Similar perception
Natural Causality
•
Historical approaches to studying life
1. Belief that some events happen through
supernatural forces (e.g. the actions of
Greek gods)
2. Belief that all events can be traced to natural
causes that we can comprehend (natural
causality)
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Natural Laws Apply Everywhere
• Natural laws are uniform in space and time
• This principle is key understanding
biological events (e.g. evolution) that
occurred before humans recorded them
• Creationism is contrary to the principle of
uniformity-in-time and natural causality
– Creationists hold that different species were
created one at a time by the direct
intervention of a supernatural being, contrary
to events we see happening today
Corollary: Evidence gathered from nature has not
been deliberately distorted to fool us
Similar Perceptions
• Assumption that all human beings
perceive natural events in fundamentally
the same way
• Common perception allows us to accept
observations of other humans as reliable
• Common perception is usually not found in
appreciation of art, poetry, and music, nor
between cultures or religious beliefs
– Value systems are subjective
– Science requires objectively gathered data
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The Scientific Method
•
Scientific inquiry is a rigorous method for
making observations
• The Scientific Method for inquiry follows
4 steps…
1. Observation of a phenomenon
– Subsequent development of questions
2. Formulation of a hypothesis
– A supposition that explains an observed
phenomenon, leading to testable
predictions
The Scientific Method
3. Testing through
experimentation
– Additional
controlled
observations
4. Development of
a conclusion
– Evaluation of
hypothesis in light
of experimental
data
The Scientific Method
The Scientific Method
• Scientific experimentation tests the
assertion that a single variable causes a
particular observation
• The experiment must rule out the influence
of other possible variables on the recorded
observations
• Controls are incorporated into
experiments
• Controls keep untested variables constant
• Scientific method is illustrated by
Francesco Redi’s experiment
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Limitations of the Scientific Method
• Can never be sure all untested variables
are controlled
• Conclusions based on the experimental
data must remain tentative
• Results of experimentation must be
communicated thoroughly and accurately
to other scientists for repetition
• Repetition by other scientists add
verification that findings can be used as
the basis for further studies
Science Is a Human Endeavor
• Human personality traits are part of “real
science”
• Scientists, like other people may be driven
by _____, _______, __________
• Scientists __________ make mistakes
• Accidents, lucky guesses, intellectual
powers, and controversies with others
________ strongly to scientific advances
Science Is a Human Endeavor
Science is a Human Endeavor
1. In the 1920s, bacteriologist ________
_________ grew bacteria in cultures
2. One of the bacterial cultures became
contaminated with a _____
3. Fleming nearly destroyed the culture when
he noticed the ______________ inhibited
bacterial growth in the culture
4. Fleming hypothesized that the mold
produced an _________ substance
5. Further tests using broth from pure
Penicillium cultures lead to the discovery
of the first antibiotic, _________
6. Fleming continued beyond a lucky
“accident” with further scientific
investigation to a great discovery
7. “Chance favors the prepared mind”
_________________
Scientific Theory
Scientific Theory
• A scientific theory ______ in definition from
that of everyday usage
– Many people use the word theory to mean
hypothesis, and “educated guess”
• A scientific theory is a general explanation for
important natural phenomena
– It is extensively and reproducibly ________
– It is more like a __________________ (e.g. the
atomic, gravitational, and cell theories)
– If compelling evidence arises, a theory may be
________
• New scientific evidence may prompt
radical revision of existing theory
• Example: the discovery of prions…
• Before 1980, all known infectious diseases
contained DNA or RNA
• In 1982, Stanley Prusiner showed that the
infectious sheep disease scrapie is caused
by a ____________________________
____________________________
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Scientific Theory
• Prions have since been shown to cause
“mad cow disease” and diseases in
humans
• The willingness of scientists to revise
accepted belief in light of new data was
critical to understanding and expanding
the study of prions
Science Is Based on Reasoning
• Inductive Reasoning
– Used in the development of scientific theories
– A _______________ is created from many
observations
– e.g., the cell theory (all living things are made
of one or more cells) arises from many
observations that all indicate a cellular basis
for life
Unifying Theory of Biology
Science Is Based on Reasoning
• Deductive Reasoning
– Generating hypotheses based on a wellsupported generalization (such as a theory)
– e.g., based on the cell theory, any newly
discovered organism would be expected to be
composed of cells
• Abundant evidence has been found to
support evolutionary theory since Darwin
and Wallace proposed it in the mid-1800s
• Those who see evolution as “just a theory”
don’t understand the scientific definition of a
theory
Unifying Theory of Biology
• Evolution explains how diverse forms of life
originated through changes in their genetic
makeup
– Modern organisms descended with
__________ from pre-existing life forms
– “Nothing in biology makes sense, except in the
light of evolution” ______________________
Three Natural Processes Underlie
Evolution
•
_____________ and _________________
formulated the basis of our modern
understanding of evolution
• Evolution arises as a consequence of three
natural processes…
1. _________________ among members of a
population
2. _____________ of those variations by
offspring of parents carrying the variation
3. _________________ of individuals whose
survival and enhanced reproduction are due
to the favorable variations they carry
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Genetic Variability
• Genetic variation arises from segments of
DNA (_______)
• Changes in genes (_________) alter the
informational content
• Mutations arise from a number of sources
– Mutations can occur from irradiation
– Mutations occasionally arise from copying
mistakes in ____ during cellular reproduction
Natural Selection
• Organisms that best meet environmental
challenges leave the ______ offspring
• Natural selection _________ genes that
help organisms flourish
Genetic Variability
• Effects of mutation
– No effect (harmless)
– A decrease in organism’s ability to function
– Death of the organism
– An increase in an organism’s ability to survive
and reproduce (rare)
• Mutations occurring over millions of years
and passed through many generations
cause members of a species to be slightly
different
Natural Selection
• _____________ are structures,
physiological process, or behaviors that
aid in survival and reproduction
• ______________ that are good for one
environment may be poor in another
Natural Selection
Natural Selection
• Species that cannot adapt to
environmental change go ________ (e.g.
the dinosaurs, illustrated by the
Triceratops
• The many different habitats
(environments) in an area coupled with
evolutionary adaptive processes produce
species variety or ______________
• Humans are responsible for ___________
the rate of environmental change (and
therefore the rate of extinction of species)
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Defining Life
• Dictionary definition of life is:
Living Things Are Composed of
Cells
• Living things are ______ and _________
– “___________________________________
_________________________________”
• Living things are more than the sum of
their parts; life is difficult to define
• The complexity and ordered interactions
of parts in living things gives rise to certain
___________ properties
Living Things Are Composed of
Cells
• The cell theory states that the cell is the
____________________
• A single cell has an elaborate internal
structure
Homeostasis
Living Things Are Composed of
Cells
• All cells contain:
– ________ that provide information to
direct the cell
– __________, small specialized
structures that perform specific
functions
– A ________________ that encloses the
fluid cytoplasm and organelles from the
outside world
Living Things Respond to Stimuli
• Organisms must maintain relatively constant
internal conditions (_______________)
• Organisms sense and respond to internal
and external environmental stimuli
– e.g. many organisms regulate body temperature
– Sensory organs in animals can detect and
respond to external stimuli like _____,
________, ______________
– Internal stimuli in animals are perceived by
________, _____________, ____________
– Plants and bacteria respond to stimuli as well
(e.g. plants to ______, bacteria to available
____________ in the medium)
• Homeostatic mechanisms include
– ___________ in hot weather or dousing oneself
with cool water
– Metabolizing more food, basking in the sun, or
turning up the thermostat in cold weather
• Organisms still grow and change while
maintaining homeostasis
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Living Things Acquire Materials
Living Things Acquire Materials
• Materials and energy required to maintain
organization, to grow, and to reproduce
• Important materials (nutrients) acquired
from air, water, soil, or other living things
• Nutrients are continuously recycled among
living and nonliving things
Living Things Acquire Materials
Living Things Acquire Materials
• Nutrients are incorporated into the bodies
of organisms
• _____________ is the sum total of all the
chemical reactions needed to sustain an
organism’s life
Living Things Grow
• Every organism becomes larger over time
– Plants, bird, and mammals grow by producing
more cells to increase their mass
– Bacteria grow by enlarging their cells; they
also divide to make more individuals
• Growth involves the conversion of
acquired materials to molecules of the
organism’s body
• Organisms obtain energy in two ways
– Plants and some single-celled organisms
capture sunlight in ________________.
– Other organisms consume energy-rich
molecules in the bodies of other organisms
• All energy that sustains life comes directly
or indirectly from the _______
Living Things Reproduce Themselves
• Organisms give rise to offspring of the
same type (_________________)
• The parent’s genetic material (DNA) is
passed on to the offspring, creating
__________ of life
• ___________ of life occurs because
offspring may be genetically different from
their parents
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Capacity to Evolve
• The genetic composition of a whole species
changes over many generations
• _________ and __________ offspring allow a
species to evolve
• Evolutionary theory states that modern
organisms descended with ___________ from
pre-existing life-forms
• _________________ is a process where
organisms with certain adaptations survive and
reproduce more successfully than others
Categorizing Life
• Domain Eukarya contains four
subdivisions or kingdoms
– Fungi
– Plantae
– Animalia
– The “Protists”
Prokaryotic and Eukaryotic Cells
• Cell types named after presence or
absence of a nucleus
– The nucleus is a membrane-enclosed sac
containing the ______________________
• Two cell types seen among all living things
Categorizing Life
• Organisms can be grouped into three
domains
– Bacteria (single, simple cells)
– Archaea (single, simple cells)
– Eukarya (one or more highly complex cells)
Categorizing Life
• There are exceptions to any simple set of
rules used to distinguish the domains and
kingdoms, but three characteristics are
particularly useful
– Cell type
– The number of cells in each organism
– Energy acquisition
Prokaryotic and Eukaryotic Cells
– _______________ (“true nucleus” in Greek)
• Larger than prokaryotic cells
• Contain a variety of organelles, including a nucleus
• Cell type found only among members of Domain
Eukarya
– _______________ (“before nucleus” in Greek)
• Only 1-2 micrometers in diameter
• Lacking organelles or a nucleus
• Cell type found in Domains________ and
_________
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Unicellularity vs. Multicellularity
• _____________ (single-celled)
organisms found in:
Unicellularity vs. Multicellularity
• _____________ (many-celled)
organisms found in Eukarya
– Bacteria
– Archaea
– The protists in Eukarya
– Kingdom Fungi
– Kingdom Plantae
– Kingdom Animalia
Ways Organisms Acquire Energy
Ways Organisms Acquire Energy
•
•
____________ (“self-feeders”)
– Photosynthetic organisms that capture
sunlight and store it in sugar and fats
– Includes plants, some bacteria, and some
protists
Science Is Part of Everyday Human
Existence
• We can use the scientific method as we
_________ things in nature
• Applying scientific thought to natural
observations does not decrease one’s
sense of wonder and appreciation
_______________ (“other-feeders”)
– Organisms that acquire energy through
ingesting molecules in the bodies of other
organisms
– Includes many ___________________
___________________________________
_______________
– Size of food eaten varies from individual
food molecules to ingestion and digestion of
whole chunks
Science Is Part of Everyday Human
Existence
• Scientific understanding and a sense of
wonder about nature are not mutually
exclusive
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