I keep six honest serving men
(They taught me all I knew);
Their names are What and Why and When
And How and Where and Who. - Kipling
Campbell and Reece, Chapter 1 (but note Glossary and Index at end, and pay
attention to several references to figures in other chapters)
Nature of scientific inquiry
Scientific inquiry and scientific method is based on observation - systematic,
You cannot always manipulate things, examples: astronomy, studying the fossil
But you can make observations like the similarities in the forelimbs of
birds and mammals. You can also make correlations, like overweight peope
are more likely to develop type II diabetes. But correlation does not prove
causation. For instance, that correlation does not prove that increasing
your weight would increase your likelihood to get diabetes. Rather there
could be an underlying genetic factor that could predispose you to diabetes
and weight gain (in a sense, simultaneously).
Also there is experimental intervention: Propose a null hypothesis vs. an
TRANSPARENCY (Fig. 1-19)
Hypotheses are small questions. You "test" these hypotheses -
answers (in the form of "rejecting the null hypothesis") are never
certain but rather involve an acceptably low probability of being wrong,
hence the involvement of statistics in experimental design. Collect more
data, and you will be more certain. You can only reject the null hypothesis.
You can not accept (or prove) the null hypothesis. In other words, absence
of data is not the same as data of absence.
In summary, the step-by-step progress of science involves statistics, and
asking the right questions, that can be answered appropriately (advanced
statistics) is called "experimental design."
"There are three kinds of lies: lies, damn lies and statistics"
Benjamin Disraeli (quoted in Mark Twain's autobiography, Chapter 29)
Ultimately, you develop theories (evolution), laws (gravity), or models
that describe how things work (like negative feedback in homeostasis).
Biology is the study of life on Earth.
Consider the categories of substance (matter): (organic) Animal, Vegetable,
(inorganic) Mineral "Is it animal, vegetable or mineral" - a question
on an old quiz show called "20 questions"
Kingdoms (At one time, 2 kingdoms were proposed (plants and animals), but
there were problems, for instance some organisms have properties of both
kingdoms. Now 5 are generally accepted.
TRANSPARENCY (Fig. 26.15)
Sometimes more are also proposed. How can the number of kingdoms be subject
to debate? Classification is not an exact science.
TRANSPARENCY (Fig. 1.4)
These cells do not have a nucleus. The suffix "karyote" refers
to the nucleus, and comes up in words like "perikaryon" (the part
of a nerve cell near its nucleus) and "karyotype" (the chromosomal
constitution of a cell).
The other four kingdoms have eukaryotic cells.
Autotroph vs. Heterotroph (self- other-feeder)
Phylogeny vs Taxonomy
Taxonomy is sometimes called "Systematics" and is based on the
Linnean system (Linnaeus 1705-1778 botanist)
Kingdom - Phylum - Class - Order - Family - Genus - Species
TRANSPARENCY (Fig. 1.10)
TRANSPARENCY (Fig. 25.7) (The point is so fundamental that it is repeated
in Chapter 25, phylogeny and systematics.) Here, domain is more inclusive
Genus - Species: binomial nomenclature
Phylum = Division for plants fungi bacteria
Homo sapiens people
Drosophila melanogaster fruit flies
Canis familiaris dogs
In phylogeny we try to draw conclusions (and diagrams) of how related organisms
are. There can be various levels of artistic license in such evolutionary
diagrams. Here (TRANSPARENCY) is an old (traditional) one I like to illustrate
fundamental points. (There is a figure in the book TRANSPARENCY (Fig. 24.24)
that is somewhat like the version I selected to show you.) Horse evolution
is shown. Here
is a display at the Carnegie museum in Pittsburgh. It is actually a graph.
Diversity is on the X axis (abscissa). That diversity in this example is
the location on Earth. The Y axis (ordinate) is time with long ago on the
bottom and now on top and split up into epochs of the geological time scale
(Eocene, etc.). Of note is that animals lower in the diagram are not just
"simpler" animals of today. Rather, today's animals are only at
the top, and some further down may be extinct, for instance, horses in the
New World until they were re-introduced.
Such a diagram branches out, hence the term "divergent evolution,"
a concept so fundamental that you should see it now even though evolution
will be covered in detail in the last quarter of the semester. One very
fundamental concept is that of homology. The wing of a bird and the flipper
of a porpoise are homologous and are descended from the same common structure
that led to your arm and hand.
Molecular biologists borrowed this strategy and produce divergent evolution
diagrams of their own (at first much to the chagrin of the comparative anatomists).
TRANSPARENCY (Fig. 19.3) - let's look ahead, and we will see that your book
gives an example of different components of the hemoglobin protein.
What is unique to life? Cell membrane contains protoplasm and somehow inside,
cells are "alive." Cells have very complex macromolecules (DNA,
Movement, Responsiveness (irritability, sensitivity)
Development, Growth, Form
Metabolism must absorb energy Catabolic, Anabolic
Homeostasis (regulation) Thermostat, servo, negative feedback. TRANSPARENCY
water, food. 1 cookie/day = 25 lb/yr
Evolution is major unifying principle 3 1/2 billion yrs
History from primordial "soup" of molecules to biology, extinctions,
It is impossible to overstate the importance of evolution to understanding
and explaining biology.
Reproduction - "Survival" in biology is to and reproduce and produce
fertile offspring. In fact, that is one definition of a species (organisms
that can reproduce and produce offspring - that is why the horse and the
donkey are not the same species even though they can mate to produce the
mule -- the mule is sterile.)
Consider this: so much energy is devoted to reproduction that reproductive
structures constitute most of the human diet. Oh? Well, grain, fruit (and
vegetables that are fruits), dairy products and eggs.
Levels of analysis
element - molecule - organelle - cell - tissue - organ -
organ system - organism - population - biosphere
(Biosphere - biology really change Earth)
Holism vs reductionism
Vitalism vs mechanism
Mentalism vs materialism
The attitude that "life is not driven by vital forces that defy explanation
but by principles of physics and chemistry" is useful for this course,
but does not touch the big questions of the meaning of life
Religion and science may seem at odds, but they can be reconciled.
Hopefully, learning biology should strengthen your appreciation of the wonder
A very useful site for SLU students, especially majors, is the Biology
Department's web page.
This page was last updated 1/22/03
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