CHAPTER 1 : Introduction – The Scientific Study of Life
I. The Organization of Life – defining the scope of
biology (AIM: How is life organized) (Figure 1.1)
A. Levels at which life is organized
1. Biosphere
2. Ecosystem
3. Community
4. Population
5. Organism
6. Organ System
7. Organ
8. Tissues
9. Cell
10. Molecule
11. Atoms
Figure 1.1 – Life’s hierarchy of organization
Hierarchy – each level builds on the one below it.
Emergent Properties – new properties emerge as one goes from a lower level
to a higher level
Structure-Function Relationship – these new properties are based on the new
structures that are generated. Structure is directly related to function (A
hammer has a structure for hitting nails and a screwdriver has a structure for
turning screws.)
NOTE: Most Biologists tend to focus on one particular level (Ex.
E. O. Wilson – studies social behavior of animals, I studied
proteins and DNA (molecular level))
II. Scientists use two main approaches to learn about
nature (AIM: What is Science?)
A. What is Science?
1. Write down your definition of science…
2. How many of you have done or used science to know
something?
a) Ex. Who taught you that objects have the tendency
to fall towards the Earth?
b) Can you prove to me that the next object I drop
will fall?
c) Can you prove that the sun will set today and night
will come?
d) Can you prove anything to me?
e) Can you prove that I am standing here??
(1) Everything we know is based on data collected by
instruments. In this case the instruments are our
eyes, ears, etc…
(2) Could there be another explanation???
(3) There can always be another explanation…
(4) Conclusion: we cannot prove with 100% certainty
anything and therefore we know nothing with 100%
certainty.
f) Everything we know is based on a level of
uncertainty…
(1) The edge of the universe…high uncertainty
(2) My standing in front of the room…low
uncertainty (but not zero uncertainty)
(3) When someone is determined to be guilty of a
crime they are guilty beyond a reasonable doubt, but
we can never say the we have proven guilt.
(4) Conclusion: we aim to make what we know have
as little uncertainty as possible and we use science to
do this…
3. derived from latin word meaning “to know”
4. A way (method) of knowing
5. The process employed to try and understand the
history of the natural universe, and how the universe
works using observable evidence.
6. So how does one do science?
B. The two main approaches to learning about nature:
1. Discovery Science (descriptive science)
a) Based on verifiable observations and
measurements
(1) Example: an ecologist observes that newborn
flying fox cling to the mothers chest during flight
(Figure 1.2) – Show Wild Parrots of Telegraph Hill (Mark Bittner’s
cherry head conures) 41:58
2. Hypothesis-Driven Science (hypothetico-deductive
reasoning)
a) Discovery science leads to questions being asked,
which will lead to suggested explanations of what you
are observing – HYPOTHESIS
**The textbook may mislead you into thinking that discovery science and hypothesis
driven science are separate entities, but they work together – observation (discovery
science) leads to hypotheses (hypothesis driven science)
b) Flashlight demonstration
(1) OBSERVATION – My flashlight doesn’t work
(2) QUESTION – What’s wrong with my flashlight?
(3) HYPOTHESIS – The flashlight’s batteries are
dead
(4) PREDICTION – If I replace the batteries the
flashlight should work
(5) EXPERIMENT – Replace the batteries with new
ones, (experiments are really just ingenious ways of
generating new observations)
(6) ANALYZE RESULTS – did the flashlight go on
or not??
(a) If not, we need to modify our hypothesis and try
again.
(b) If it does, then our hypothesis survives
c) This process is called the SCIENTIFIC METHOD
(1) Observations – from discovery science, earlier
tests (experiments), etc…
(2) Questions – about unclear aspects of the
observations (How? Why? When? Where? Etc…)
(3) Hypothesis – a tentative explanation for an
observation
(4) Predictions – What you would predict to happen if
your hypothesis were correct
(5) Tests (Experimental) – Determine if the
predictions are supported or not. The results are used
as new observations for another investigative cycle
d) There are two different types of reasoning present
in the Scientific Method: Inductive vs. Deductive
reasoning
(1) Inductive
(a) Derives general principles from a large number
of specific observations – everything I drop falls to
the earth, therefore all things fall to the earth
(b) Observations  hypothesis
(c) specific to general
(2) Deductive
(a) Sherlock Holmes
(b) From general hypotheses we try and make
specific predictions.
(c) Hypothesis  conclusions
e) Other examples of the scientific method in action
(1) Gravity
(2) Your doing science right now!!
(3) Medical doctors
(4) My drive to work example
(5) Darwin – Theory of Evolution
(a) Publish results for scientific community
(b) Theory vs. Law
(i) Theory is a collection of hypotheses all
about the same general principle that has
stood the test of time (never been broken by
any observation)
(ii) Automobile analogy
(a) Theory of Evolution, Cell Theory,
etc…
(iii)Law – concise explanation of an action
or set of actions (sometimes written as a
simple equation)
(a) Law of Gravity, Laws of Motion,
Laws of Thermodynamics, etc…
(c) Scientists try to falsify (disprove) hypotheses, it
doesn’t prove anything – ex. It can’t prove that the
next thing I let go of will fall to the Earth.
(d) Science is tentative
(i) Another example: Newton and Einstein
– nova video
f) Science is fallible (liable to be erroneous)
(1) Doubt – the greatest tool of any scientist (and
everyone else)
(2) Don’t always believe what you hear and read, and
question everything regardless of who the
information is coming from.
g) Real-life Example – plants in brackish tidal marsh
h) Lancet – mental health article
C. Controlled Experiments – A special class of experiments
1. Example – Earth Worm Droppings as fertilizer
a) Control group
b) Experimental group
c) Variable – that which is changed or altered in the
experiment
(1) Independent variable – variable adjusted by the
scientist – there should be only ONE!
(2) Dependent variable – the variable that is being
measured by the scientist
d) Experimental validity
(1) Randomly chosen sample group
(2) Large sample size
(3) Must be done more than once (many trials)
2. Experiments MUST be repeatable by others
D. Design your own experiments
E. A case study from the Biological Science (A PredatorPrey System - mimicry)
1. OBSERVATIONS –
1) Jumping spiders defend theirs territories against
other members of their population by waving their
legs at them.
2) Certain fly species like the snowberry fly, when
approached by jumping spiders, wave their wings,
which have markings that resemble spider legs
2. QUESTION – What is the function of the flies’ wing
markings and waving behavior?
3. HYPOTHESIS – The markings and wing waving
increase survival of the flies by causing jumping spiders
to flee
4. PREDICTION – If one masks the flies wing marking
with dye, the spider should pounce on these flies more
often
5. EXPERIMENT
6. PREDICTED RESULT
The diversity of life can be arranged into three
domains (or 5 kingdoms!?)- [15-14-ClassificationAnim.mov]
III.
A. ~1.5 million known species / estimated 30 million
species on planet – we need to organize!!!!
B. Species – populations of organisms who have the
potential to interbreed and produce FERTILE offspring
C. Taxonomy – branch of science concerned with naming
and classifying the diverse forms of life
D. Prokaryotes vs. Eukaryotes
1. Prokaryotes – lack a nucleus
2. Eukaryotes – have a nucleus and internal structures
called organelles.
E. The 3 domain system:
1. Bacteria (Eubacteria) - prokaryotes
2. Archaea (Archaeabacteria) - prokaryotes
3. Eukarya - eukaryotes
F. The 5 kingdom system
1. Monera – single celled, only cells without a nucleus
2. Protista – Protozoans and algae (predominantly singlecelled)
3. Fungi – molds, yeast, and mushrooms – decompose
and absorb nutrients from dead organic matter
4. Plantae – complex form, photosynthesis (autotrophs –
autos = self, trophe = nutrition (Greek))
5. Animalia – complex form, eat other organisms
(heterotrophs – heterone = (an)other, trophe = nutrition)
G. Classification System (Taxonomy) – human taxonomy
1. Kingdom
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species
8. Kings Play Chess On Flat Glass Squares, King Phillip
Came Over From Germany Singing
H. BINOMIAL NOMENCLATURE - Carolus Linnaeus
1. Scientific names are applied by using Genus species
I. Mention E.O. Wilson and the encyclopedia of life
IV. Phylogenetic trees strive to represent evolutionary
history
A. Phylogeny (phylon = tribe, genesis = origin (Greek)) –
the evolutionary history of a group of organisms
B. Phylogenetic trees – diagrams that trace evolutionary
relationships as best they can be determined.
1. It is simply a very large family tree looking back to our
ancestors. If we trace the ancestry of all organisms back,
we will meet at one organism, at one place in time. (For a
great book on this subject try The Ancestors Tale by
Richard Dawkins).
V. Dichotomous (Identification) Key
A. How would you go about figuring out the species
assignment of a living thing?
B. Dichotomous keys are a method for doing just that
C. It is very similar to the game – 20 questions
D. Each question narrows down the possibilities further
and further until there is only one answer.
E. Tree Branch demonstration using either website below:
1. http://www.dnr.state.wi.us/org/caer/ce/eek/veg/treekey/i
ndex.htm
2. http://www.uwsp.edu/cnr/leaf/Treekey/tkframe.htm
VI. Unity in Diversity: All forms of life have common
features – Characteristics of Life:
A. Although life appears to be quite diverse, we all share
common properties. Taken together, these properties
distinguish living (biotic) from non-living (abiotic).
1. Order (organized): all organisms are made of one or
more cells (the basic units of structure and function). The
internal workings of cells as well as the interactions
between cells in multi-cellular organisms are highly
ordered (hierarchy of life).
a) All cells share similar molecules (ex. DNA)
b) The way that genetic information is encoded in
DNA is the same for all cells in all known organisms
c) The information stored in DNA is used to build the
organism and give the organisms the properties that
distinguish living (biotic) from non-living (abiotic)
d) DNA is a parts list – It is a list of every protein in
the organism and how to assemble them.
2. Regulation (homeostasis): The environment outside an
organism may change markedly, but regulatory
mechanisms maintain the internal environment of the
organism within life sustaining limits.
a) The maintenance of our internal environment is
called homeostasis.
(1) Ex. When you exercise, you will generate heat
and begin to sweat. Sweating is the bodies way of
cooling itself down in an attempt to maintain the
body’s temperature around 98.6F – homeostasis.
(2) What about if you get too cold?
3. Growth and Development
4. Energy Utilization – organisms must take in energy
and transform it to perform life’s activities. In order to do
this cells carry out various chemical reactions.
a) Metabolism – combination of all the chemical
reactions that occur in an organism
b) Ex. Moving your arm requires energy. This
energy, in the case of heterotrophs, comes from the
food we eat.
5. Response to the environment
a) Ex. You are hiking in the woods when you start to
smell smoke and see large flames in the distance. You
turn around and head in the other direction.
b) Ex. You touch a hot iron and pull your hand away.
6. Reproduction: the passing of hereditary information to
new organisms of the same type
7. Evolution: the capacity of a species to change over
time. It is the central unifying feature of life from its
inception almost 4 billion years ago.
VII. The Life Processes: these are the processes
required by living things to maintain life.
1. Nutrition – all the activities by which an organism
obtains food from the environment and breaks it down
into a form that can be absorbed by its cells.
2. Transport – involves the absorption and distribution
(circulation) of essential materials throughout the
organism.
3. Cell Respiration – Cell respiration (different from
breathing) releases energy from food by a complex series
of chemical reactions.
4. Excretion – process by which wastes of metabolism
are removed from the organism.
5. Synthesis – the process by which simple molecules
are combined chemically to form more complex
molecules.
6. Growth – increase in size of an organism resulting
from the synthesis of food substances into new materials
and new structures.
7. Responding to internal and external stimuli
8. Reproduction – process by which organisms give rise
to offspring.
B. Non-living (abiotic) things may carry out some of these
processes, but living (biotic) things carry out ALL of them.
C. HNTRSGERMR
VIII. Evolution explains the unity and diversity of life – it
is the core theme of all life
A. THEORY – a widely accepted explanatory idea that is
broad in scope and supported by a large body of evidence
B. Charles Darwin – On the Origin of Species by Means
of Natural Selection – showed that evolution can be
explained by the diversity of life and its underlying
commonalities
C. Theory of Natural Selection – proposed by Darwin to
explain evolution
1. Heritable variations must occur in a population
2. Environmental factors favor one variation over another
in terms of survival and reproductive success
3. The evolution of new species comes from the
accumulation of small changes over long periods of time
D. ADAPTATIONS – features that evolved by means of
natural selection
E. Evolution does NOT create!!! It selects from what is
available!!
IX. Living organisms and their environment form
interconnecting webs
A.
Living things are intertwined with their environment,
which included both living and non-living entities.
B. Ecosystems rely on the flow of chemical nutrients
and energy
1. Chemical - The most basic chemicals needed for life
(atoms making CO2, H2O, O2, N2, Minerals, etc...) are
constantly being recycled between living and non-living
entities.
2. ENERGY
a) 1st law of thermodynamics - energy cannot be
created or destroyed, it can only change form.
b) Energy, Work, and Force
c) Three sources of energy on Earth
(1) Sun
(2) Geothermal
(3) Gravitational pull of the moon
d) Flow of Energy example
(1) Energy comes from the sun in the form of light
(2) Plants (some prokaryotes and protists also) trap
the light’s energy and use it to make food molecule
from CO2 and H2O – light energy now stuck in the
food molecule
(3) Animals need to eat the plants, etc… to get the
energy
(4) Other animals will eat these animals to get the
energy, and so on.
X. We are biological organisms and thus we are
intimately connected to biology in our lives:
A. Birth and death, population, nutrition, exercise, dieting,
medicine, agriculture, endangered species, pollution,
environmental changes (global warming) etc…