Chapter One
Themes in the
Study of Life
Characteristics of Life
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Life can’t be summed up into
a simple, one-sentence explanation
How do you know that a tree is alive and a
rock is not?
All living organisms share certain
characteristics
Do you remember what some of these are?
Reproduce
Contain DNA
Adapt to environment
Grow and develop
Made up of cells
Have definite lifespan
Utilizes energy
Responds to stimuli
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Levels of life
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Life is organized into many structural levels.
Biological structural levels build upon the
level below it
 cells 
 tissues 
 organs 
 systems 
 Individual organism 
 populations 
 communities 
 ecosystems 
 Biosphere
*And cells of course are made up from even smaller
parts.
Each Level of Biological Organization Has
Emergent Properties Continued
 Order
is all around us. Notice the
pattern and order in this sunflower.
 Emergent
properties within these
levels manifest themselves as a
result of dynamic and unique
interactions between components
Understanding Biological Organization and its
Many Levels is Fundamental to the Study of Life
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Scientists cannot fully explain a higher level of order
from a critical analysis of it partsFor example: what good is the handle of a hammer
without the head?
Holism = disrupting a living system interferes with
the meaningful explanation of its processes
But, biological structural levels build upon the level
below it, so scientists cannot critically analyze living
systems without taking them apart
Reductionism = reducing complex systems to
simpler components that are more manageable to
study
Cells are an Organism’s Basic Units of Structure
and Function
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The Cell Theory = all living things consist of cells & cells
come from other cells
Prokaryotic cells = bacteria / NO true nucleus
Eukaryotic cells = all other organisms / membranebound nucleus and endomembrane system
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In order for a species to continue, organisms
must reproduce. DNA makes it possible for
the heritable information to be passed on.
DNA - deoxyribonucleic acid
 Encoded biological instructions
 Substance of genes
 Units of inheritance
DNA structure
 Long chain made of four nucleotides
 Adenine, cytosine, guanine, and
thymine
 Specific sequential arrangements
encode the precise information in a
gene
Structure and Function are Found at all Levels
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DNA encodes a message which dictates the
growth and development of the organism
Each cell, organelle, organ, etc. has its own
function or duty to perform.
In multicellular organisms, genes are turned on or
off in order to specialize the functions of the cells
Form fits function
 Analyzing a biological structure clues us to what
it does and how it works
 Knowing function of a structure provides insight
about its construction
Understand your subject or specimen
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Cells may be the units of organisms but it is
the organism that is the unit of life
It is not enough to merely learn what parts
make up an organism, but how it grows,
interacts, lives, and responds.
Questions to ask about any organism to be
studied:
 What
kind of organism is it?
 Where does it live?
 How does it acquire nutrients and other resources
from the environment?
 How is the organism equipped for its way of life?
Diversity and Unity
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Nearly 2 million species of living things
have been identified, but it is estimated
there are between 5 - 30 million total
species on Earth
~260,000 plants
~50,000 animals
~750,000 insects
Everything has its own niche and purpose in
life (diversity and uniqueness), but every
living creature needs interaction and support
to serve a greater purpose (unity)
Taxonomy
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With so many types of organisms, a system of
classification was necessary
Carolus Linnaeus
Bionomial nomenclature
Taxonomy - naming and classifying species
 Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 Species
KINGDOM
Animalia
PHYLUM
Chordata
CLASS
Mammalia
Figure 22-1(1)
Page 422
ORDER
Carnivora
FAMILY
Felidae
GENUS
Felis
SPECIES
Felis catus
Figure 22-1(2)
Page 422
6 Kingdom vs. Domains
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The six kingdom system of taxonomy categorizes
organisms based on cell structure and nutrition
The domain system on the other hand is based on
molecular differences
There are 3 domains:
Domain Archaebacteria - contains the archaea kingdom
Domain Eubacteria - contains the eubacteria kingdom
Domain Eukarya - contains kingdoms animalia, protista,
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fungi, and plantae
*Phylogeny will be discussed when we get to evolution unit
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Domain
Eubacteria
(bacteria)
Figure 22-2
Page 423
Domain
Archaea
The three domains
Common ancestor
of all living organisms
Domain
Eukarya
Kingdoms
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There are 6 Kingdoms:
Archaea - extreme bacteria; more related to euks
Eubacteria (Monera) - typical bacteria; prokaryotic;
peptidoglycan cell walls
Protista - single-celled, aquatic, euk
Fungi - multi-celled; euk, decomposers
Plantae - photosynthetic; euk; multi-celled
Animalia - consumers; euk; multi-celled; 9 phyla
Eubacteria
Archaebacteria
Protista
Plantae
Protista
Figure 22-3
Page 424
Animalia
Common ancestor
of all eukaryotes
The six-kingdom
system of classification
Common ancestor
of all living organisms
Fungi
Bacteria
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We’ll study in depth during microbiology and DNA
technology
Protista
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Protists produce 70% of our oxygen, but not all
of them are photosynthetic
Vary in size, structure, mode of locomotion, and
reproduction
Endosymbiont Theory: the accepted belief is that
mitochondria and chloroplasts originated from
symbiotic relationships between early protists and
bacteria
Chloroplasts - from photosynthetic prokaryotes
Mitochondria - from aerobic prokaryotes
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Divided into 8 major groups:
Excavates, opisthokonts, discicristates,
alveolates, heterokonts, cercozoa, amoebozoa,
and plants
NO- you don’t need to memorize these
The plant category also includes plants and algae
Opisthokonts include members of the animal
kingdom and fungi kingdom as well
too confusing of a system
Fungi
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Most are filamentous; made up of hyphae forming an
aggregation called mycelium
Most have cell walls of chitin
Most produce by spores (produced sexually or asex)
5 phyla are identified (but only 4 true phyla exist)
Chytridiomycetes (most primitive) -only fungi with
flagella
Zygomycetes - black bread molds
Ascomycetes - sac fungi (yeasts, mildews, colored
molds, morels and truffles)
Basidiomycetes - mushrooms, rust, smut, and puff
balls
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Some fungi play an important ecological role
 Mycorrhizae
- a type of fungus which decomposes
organic material in soil
 Benefit plants by increasing their absorptive surface
area
 Roots supply fungus with sugars, amino acids, and
other organic substances
 Scientists have measured movement of organic
materials from one tree species to another
without
with
Plants
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You’ll learn everything you ever wanted to
know about plants before we do
photosynthesis in a few weeks.
Animalia
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Animals can be classified according to:
body symmetry - radial or bilateral symmetry or
asymmetrical
body cavities: coelomates, acoelomates,
pseudocoelomates
Coelom : a fluid-filled cavity lined with mesoderm
evolutionary relationships based on molecular
data (DNA, rRNA, and Hox genes)
Animal Phyla
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1. Porifera - sponges
Aquatic, mostly marine, typically asymmetrical,
multicellular but do not have tissues, regenerative
capabilities
2. Cnidarians - hydras, anemones, coral, jellyfish
Radially symmetrical, stinging cells called
nematocysts
Diploblastic (only 2 germ layers)
Animal Phyla
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Acoelomates:
3. Platyhelminthes - flatworms (flukes,
tapeworms)
No body cavity, bilaterally symmetrical, simple
nervous system with ganglia
Triploblastic (endoderm, mesoderm, ectoderm)
Animal Phyla
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Pseudocoelomates:
4. Nematodes - round worms (hookworms,
pinworms, Trichina)
All parasitic, lack a circulatory system, covered by
cuticle, false body cavity between mesoderm and
endoderm
Triploblastic (endoderm, mesoderm, ectoderm)
Animal Phyla
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Coelomates:
I - Protostomes
5. Molluska - squid, snails, clams, oysters
Soft body (usually covered with a shell), foot for
locomotion, visceral mass contains body organs,
reduced coelom, mantle secretes shell (if present),
open circulatory system (except in cephalopods octopus, squid, nautilus), triploblastic
6. Annelida - segmented worms (earthworm &
leech)
Segmentation, setae, closed
circulatory system, triploblastic
Animal Phyla
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Coelomates:
I - Protostomes
7. Arthropoda - crustaceans, trilobites,
centipedes, arachnids, insects
Exoskeletons, paired, jointed appendages, open
circulatory system, nervous system of brain,
ladder-like nerve cords and often compound eyes
Aquatic arthropods have gills while terrestrial
arthropods have book lungs or trachea
Triploblastic (endoderm, mesoderm, ectoderm)
Animal Phyla
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Coelomates:
II - Deuterostomes
8. Echinodermata - sea stars, sea lilies,
crinoids, sand dollars
Larval stage is bilaterally symmetrical and
adult form is radially symmetrical
Nerve net, no excretory organs, endodermis,
calcareous plates covered by epidermis,
tube feet
Triploblastic (endoderm, mesoderm, ectoderm)
Animal Phyla
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Coelomates:
II - Deuterostomes
9. Chordata - vertebrates and invertebrates
At some point in life cycle, all chordates have:
Notochord (flexible supporting rod), dorsal hollow
nerve cord, pharyngeal slits, and post anal tail
Coelomates with bilateral symmetry, endoskeleton,
closed circulatory system with ventral heart
Triploblastic (endoderm, mesoderm, ectoderm)
Animal Phyla
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A closer look at vertebrates:
2 pairs of appendages, closed circulatory system
with ventral heart, vertebral column of bone or
cartilage, anterior cranium, paired kidneys,
complete digestive tract with large digestive glands
Divided into 3 classes of fish (osteichthyes,
chondrichthyes, agnatha) and 4 classes of
tetrapods (amphibians, reptiles, birds, mammals)
Germ Layers
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We’ve used the term triploblastic, but what does it
mean?
3 germ or embryonic layers:
Ectoderm - becomes outer covering and nervous
sytem
Mesoderm - becomes most internal organs
Endoderm - becomes lining of the gastrointestinal
tract
Quantifying Biology
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Biology is the study of any and/or all of these
living organisms we just mentioned
Biology does not only involve observations, but
includes quantifying, manipulating, and analyzing
data in order to draw conclusions
Review the Scientific Method:
Observations, Problem/Question, Hypothesis,
Experiment and Data Collection, Analysis and
Conclusions, Repetition and Sharing
Let’s focus briefly on manipulating and
interpreting data
Data Collection
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All data collected should be
accurately measured or counted
Should also be recorded carefully
and neatly
Data tables should be done with
ruled lines and with appropriate
titles and units
Statistical Analysis
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Correctly manipulating data enables scientists
to demonstrate significance of data and to
validate claims
When you learn of a claim that a scientist is
making, don’t you want to know what the
supporting data is?
Statistics Terminology
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Mean = arithmetic average (sensitive to outlying
data)
Median = the value that splits the number of data
entries in half (not sensitive to outlying data)
Range = the spread of the data from least to
greatest
Standard deviation = a calculated value indicating
how much the data varies around the mean value
Error bar = vertical reference lines on graphical
distribution of data that illustrates points of std
deviations
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To calculate Standard Deviation manually:
Take EACH data point and subtract the mean
value
Square each of these values and add them up
Divide this sum by (the number of data entries
minus 1)
Then, take the square root of the answer
The result is the Standard Deviation and is
denoted with a +/- sign because it falls on either
side of the mean value
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Standard Deviation using the TI Calculators:
Hit <STAT> and <1> to get to the lists screen
In the L1 column, enter your data
Hit <STAT> again
Choose CALC and then 1-Var Stats
Hit <ENTER>
It gives you the mean, the sum of the values, the
sum of the squared differences, and the standard
deviation (Sx)
(If you scroll down, it also gives you the min and
maximum values and the median)
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t-test = a test used to deduce the significance of
the difference between two sets of data
On your TI Calculator:
Hit <STAT> and <EDIT> to enter your lists in
column L1 and column L2
Hit <STAT> again and scroll over to <TESTS>
Choose <4> for two sample T test
Make sure the two column heading appear from
your data
Scroll down and choose calculate
The t value and df (degrees of freedom) are given
Now, use your table to determine acceptance
Correlation
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When a correlation exists between two sets of
data, this does not establish that there is a causal
relationship between the two variables being
examined