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 two 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 multicellular,
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 multicellular,
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.
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