Transcript Chapter 1

Chapter 1
The Science of Biology
How do we determine whether
something is living?
I. The Characteristics of Life
1.Cellular Organization (made
of 1 or more cells)
2.Ordered Complexity
(complex)
3.Sensitivity (responds to
stimuli)
The Characteristics of Life
(continued)
4. Growth, Development, and
Reproduction
5. Energy Utilization (uses energy)
The Characteristics of Life
(continued)
6. Homeostasis (balance between
different systems)
7. Evolutionary Adaptation (those
surviving have the best adaptations)
II. Hierarchy
1. Cellular Level
a. Atom
b. Molecules – atoms bonded
together
c.Organelles – made of
macromolecules
d. Cells – organelles work together
i. Unicellular organisms
ii. Multicellular organisms
II. Hierarchy (continued)
2. Organism Level
a. Tissues – cells working together
b. Organs
c. Organ system
II. Hierarchy (continued)
3. Population Level
a. Population – Organisms of the
same species living together
b. Species – Organisms that can
interbreed
c. Biological community –
Populations of different species
living together
II. Hierarchy (continued)
4. Ecosystem – Living and nonliving
that interact in the same area
5. Biosphere – Any place on Earth
that contains organisms
III. The Nature of Science
(Scientific Method)
A.Science uses both deductive and
inductive reasoning
1. Deductive reasoning
a. Uses general ideas to lead to
a specific conclusion
b. Example:
Gravity causes objects to fall
This apple fell
Therefore gravity caused the apple to fall
2. Inductive Reasoning
a. Uses specific ideas to
lead to a general conclusion
b. Example:
Hillary Clinton has hair
Barack Obama has hair
Therefore all politicians have hair.
Scientific
Method
B. Hypothesis-driven science
makes and tests predictions
1. Hypothesis
a. An explanation for a group of
related observations
b. TESTABLE – can be proved or
disproved
Example: Observations
• Soup exposed to the air spoiled — bacteria grew in
it. Containers of soup that had been boiled for one
hour, and then were sealed, remained sterile. Boiling
for only a few minutes was not enough to sterilize
the soup. Louis Pasteur had previously
demonstrated that the dust collected by drawing air
through a cotton ball contained large numbers of
bacteria, hence he knew that bacteria were present
in the air and could be filtered out by using a cotton
ball. He also knew that bacteria would settle out on
the walls of a long, bent, glass tube as air was
passed through it.
• Question: Is there indeed a “life force”
present in air (or oxygen) that can cause
bacteria to develop by spontaneous
generation (from nonliving particles)?
• Germ Hypothesis: There is no such life
force in air, and a container of sterilized
broth will remain sterile, even if exposed to
the air, as long as bacteria cannot enter the
flask. Life comes only from preexisting life.
2. Experiment or Test – proves or
disproves hypothesis
a. Variables (aka experimental variable, test
experiment) changed in experiment
b. Control (aka control variable, control
experiment) stays the same in experiment
• Test - Pasteur boiled broth in various-shaped flasks to
sterilize it, then let it cool. As the broth and air in the
containers cooled, fresh room air moved into the
containers. None of the flasks were sealed — all were
exposed to the outside air in one way or another.
Control group — Some flasks opened straight up, so
not only air, but any bacteria present in that air, could
get into them.
Variable or experimental group(s) — Pasteur used
some flasks with long, S-shaped necks (swan-neck
flasks) and closed others with cotton plugs. This
allowed air to enter these flasks, but the long, swan
neck or the cotton balls filtered out any bacteria
present in that air. He subsequently broke the long
necks off some of the swan-neck flasks.
3. Using predictions
a. If the experiment disproves the
hypothesis, the hypothesis is rejected or
modified
b. If the experiment supports the
hypothesis, then more tests are carried
out to see if the hypothesis is valid
c. If the hypothesis is valid, it should be
able to correctly predict the outcome of
these experiments
• Data: Broth in flasks with necks opening straight up
spoiled (evidence: a bad odor and cloudiness in a
previously clear broth, microscopic examination of
the broth confirming the presence of bacteria), while
broth in swan-neck flasks did not, even though fresh
air could get it. Broth in flasks with cotton plugs did
not spoil, even though air could get through the
cotton. If the neck of a swan-neck flask was broken
off short, allowing bacteria to enter, then the broth
became contaminated.
• Conclusion(s): There is no such life force in air,
and organisms do not arise by spontaneous
generation in this manner. To quote Louis Pasteur,
“Life is a germ, and a germ is Life. Never will the
doctrine of spontaneous generation recover from
the mortal blow of this simple experiment.”
C. The nature of scientific theories
1.Theory – a generally
accepted principle supported
by scientific evidence.
Example: Evolution
Charles Darwin
An Example of the Scientific Method
• Traveled around the
world in the HMS
Beagle.
Observations
• Studied 14 species of finches that
varied slightly in appearance.
Observation: Malthus explains
populations grow faster than their
food source.
Observation: Artificially bred
pigeons creates great variation
Hypothesis – Natural Selection
1. Finches are similar b/c they descended from a
common ancestor. They are different b/c the
food available at each island varied.
2. Organisms produce more offspring than can
survive. Those who do survive have a
physical and behavioral advantage which they
pass on to their offspring through genes.
3. Nature also produces variation within species.
Testing Natural Selection
1. Fossil Record – intermediate species
2. Age of Earth – Radioactive decay reveals
the age of Earth and organisms
3. Heredity - Genetics
4. Comparative Anatomy – homologous
structures
5. Molecular Evidence – Similarities in DNA
sequences
Strong evidence supports the hypothesis.
Evolution is now a scientific theory.
IV. Unifying Themes in Biology
A. Cell Theory
1. All organisms are made of cells.
2. All cells come from preexisting cells.
B. The Molecular Basis of
Inheritance Explains the
Continuity of Life
1. DNA – set of instructions
for organisms
2. Genes – passed down
to offspring - heredity
C. Relationship between Structure and
Function Underlies Living Systems
1. Form fits function
a. The aerodynamics of a birds
wings allows it to fly
b. Elephant ears are large with
great surface area to release heat.
D.Diversity of Life Arises by
Evolutionary Change
1. 260,000 plants
2. 50,000 vertebrates
3. 750,000 insects
4. Widespread use of antibiotics
has selected for antibiotic
resistant bacteria
E.Evolutionary Conservation Explains
the Unity of Living Systems
1. KPCOFGS
2. Compare DNA, proteins
King......Kingdom
Philip....Phylum
Could.....Class
Only......Order
Find......Family
Good......Genus
Students..Species
F.
Cells are Information
Processing Systems
1. Communication through the cell
membrane
2. Homeostasis
G.Emergent Properties Arise from the
Organization of Life
1. Total sum of all Parts
H. Science as a Process (Scientific Method)
1. Darwin’s Hypothesis to the Theory
of Evolution
I. Energy Transfer
1. Photosynthesis
2. Respiration
3. Food Web
J. Regulation (Homeostasis)
1. Body temperature is regulated by the
brain through feedback systems.
2. Predators regulate prey populations
K.Interdependence in Nature
1. EXAMPLE: Trees interact with
soil (water and minerals), air
(gas exchange), sunlight and
animals (food)
2. Symbiosis
L.Science, Technology and
Society
1.Good and Bad: live longer v
environmental impact
2.Tools: Microscopes, X-rays