1.1
How to Define Life
A. Living Things Are Organized
1. Organization of living systems begins with the cell; cells are made of molecules
that
contain atoms.
2. Cells combine to form a tissue
(e.g., nervous tissue).
3. Different tissues combine to make
up organs (e.g., the brain).
4. Organs work together as organ
systems (e.g., the brain, spinal cord, etc.)
5. Multicellular
organisms may have many organ systems.
6. A species in a particular area
(e.g., gray squirrels, an oak forest) constitutes a population.
7. The populations inhabiting an
area at the same time make up a community.
8. A community plus its physical
environment constitutes an ecosystem.
9. Each level of organization has
emergent properties beyond the sum of the parts.
B. Living Things Acquire Materials and Energy
1. Maintaining organization and carrying on life requires outside sources of
energy.
2. Food provides nutrient molecules
used as building blocks or for energy.
3. Energy is the
capacity to do work; it takes work to maintain organization of the
cell and
organism.
4. Metabolism is all
chemical reactions that occur in a cell.
5. Ultimate source of energy for
nearly all life on earth is the sun through photosynthesis.
6. Organisms must remain homeostatic
or keep themselves stable in temperature, moisture
level,
acidity, etc. by physiology and behavior.
C. Living Things Respond
1. Response often results in movements of plant or animal.
2. Ability to respond helps organism
survive.
3. Responses to environment
altogether constitute behavior of organism.
D. Living Things Reproduce and Develop
1. Reproduction is the ability of an organism to copy itself.
2. Bacteria, protozoa, etc. simply
split into two.
3. Multicellular
organisms may pair sperm with egg; resulting in an immature individual,
which
develops to become the adult.
4. Organisms develop as result of
blueprint of instructions encoded in their genes.
5. Genes are made of long molecules
of DNA that specify how the organism is ordered.
E. Living Things Have Adaptations
1. Adaptations are modifications that make an organism suited to
its way of life.
2. Natural selection
is process by which species become modified over time.
a. A species
is a group of interbreeding individuals.
b. In
natural selection, members may inherit a genetic change that makes them
better suited to a particular environment.
c.
Consequently, these members are more likely to produce more surviving
offspring.
3. Descent with modification
a. All
living things share the same basic characteristics: cells, DNA, etc.
b.
This unity suggests all organisms descended from common ancestor -- the first
cell.
c.Adaptations to different ways of life explain diversity
of life-forms.
1.2.
How the Biosphere is Organized
A. Populations
1. All ecosystems together
make up the biosphere, the thin layer of life that encircles the
earth.
2. Populations within a community
interact among themselves and with the physical and
chemical environments, forming a ecosystem.
3. Food relationships form a
major part of interaction between populations.
4. Large ecosystem keeps
cycling its raw materials (e.g., water and nitrogen)
5. In contrast, energy flows
through an ecosystem and is eventually lost as heat.
6. A constant supply of solar
energy is require for an ecosystem and for life to exist.
B. Tropical Rain Forest, a Terrestrial Ecosystem
1. Most complex ecosystem in the world; found at low altitudes near equator.
2. Require plentiful sun and
rainfall all year long.
3. Broadleaf evergreen canopy
intercepts most sunlight at different layers.
4. Most organisms live in canopy;
includes tree sloths, monkeys, birds, butterflies,
bats, etc.
C. The Human Population
1. Human populations tend to modify existing ecosystems for own purposes.
2. Fewer natural cycles are able to
function adequately to sustain human populations.
3. For example, rain forests absorb
carbon dioxide, keep temperatures lower,
and
lessen acid rain.
4. Preservation of biodiversity
(variety of populations) is extremely important.
1.3. How Living Things Are Classified
A. Taxonomy and Scientific Names
1.Taxonomy is the discipline of identifying and classifying organisms.
2.Scientific name is
binomial.
3.Scientific name of a species
-- underlined or in italics -- contains twwo parts:
first name is genus;
second name is a specific epithet of organism.
4.Classification uses groups:
species, genus, family, order, class, phylum/division,
kingdom, and domain.
B. Five Kingdom and Three Domain Systems
1. Living things on the planet have commonly been categorized into five
kingdoms:
a. Monera -- prokaryotic, unicellular organisms
(archaebacteria and eubacteria);
b. Protista -- eukaryotic, unicellular,
colonial, and simple multicellular
organisms (protozoa, etc.);
c. Fungi
-- eukaryotic, mostly mmulticellular, filamentous
organisms that absorb their nutrients;
d. Plantae -- eukaryotic, multicellular,
and photosynthetic organisms (plants);
e. Animalia -- eukaryotic, multicellular
organisms (animals) that ingest their nutrients.
2. Biochemical evidence suggest
kingdoms might be organized into three higher domains:
a. Archeae (ancient prokaryotes);
b. Bacteria
(more derived prokaryotes);
c. Eukarya (eukaryotes, including the protists, fungi, plants and animals).
3. Some books are now using the Six
Kingdom System as Follows:
a. Archeabacteria -- ancient prokaryotes
b. Eubacteria -- more derived prokaryotes
c. Protista -- eukaryotic, unicellular,
colonial, and simple multicellular
organisms (protozoa, etc.);
d. Fungi
-- eukaryotic, mostly mmulticellular, filamentous
organisms that absorb their nutrients;
e. Plantae -- eukaryotic, multicellular,
and photosynthetic organisms (plants);
f. Animalia -- eukaryotic, multicellular
organisms (animals) that ingest their nutrients.
1.4.
The Process of Science
A. Science is one way humans understand the natural world.
1. Science investigation is limited to questions that can be studied by direct
or indirect observations.
2. An observable event is
called a phenomenon.
3. Formulating a hypothesis
involves inductive reasoning; (i.e., isolated facts are
used to generalize about an observed phenomenon).
4. Science considers hypotheses
that can be tested either in the laboratory or in a field setting.
B. A Field Investigation
1. Deductive reasoning begins with a general statement and infers
a specific
conclusion;
it is often an "if...then" statement.
2. Controlled experiments
have a control group that does not experience the tested
variable;
this
eliminates the possibility results are due to nonidentifiable
chance events.
3. Data are the
results of experiments.
a.
Data are careful counts or descriptions.
b.
Careful records must be kept so other researchers can repeat the experiment.
4. By studying results, a researcher
comes to a conclusion.
5. Results can falsify
or show a hypothesis to be untrue; some think of science as what
is left after alternative hypotheses have been rejected.
6. Science findings are reported in science
journals so results are available to the
research community.
C. A Laboratory Investigation
1. Some investigations are held in a laboratory where conditions can be kept
constant.
a. A variable is a factor that can cause an observable change.
b. The experimental variable is the step that is deliberately
manipulated.
c. A dependent variable is component of an experiment that
changes due to
the experimental variable.
d. Sweetener S discussion is example of a controlled experiment.
D. An Observational Investigation
1. Some investigations are based on observations rather than experimentation.
2. The science steps previously
listed still apply.
3. Ultimate goal of science is to
understand natural world in terms of theories;
examples include Cell Theory, Biogenesis Theory, Theory of Evolution and Gene
Theory.
E. The Scientific Method
1. Scientific method is a set of outlined procedures.
2. Actual science research may not
follow this rigid outline and may involve
chance
(e.g., Alexander Fleming's discovery of penicillin).
F. Scientific Theories in Biology
1. Ultimate goal is to understand the natural world in scientific theories,
conceptual schemes supported by a broad range of data.
2. Basic theories of biology are:
a. Cell
theory: all organisms are made of cells.
b. Biogenesis
theory: life only comes from life.
c. Evolution
theory: living things have a common ancestor and are adapted.
d. Organisms
contain coded information that determines their form and behavior.
3. The terms "law" and
"principle" are also used for generally accepted theories.