Transcript WHAT IS LIFE?

WHAT IS LIFE?
Chapter 1
All living things exhibit five
characteristics in combination.
A. Characteristics of Life
1. Organization
 chemical
(atom -> molecule ->
macromolecule)
 organelle
 cell*
 tissue
 organ
 organ
system
 multicellular organism
Each level of biological organization
exhibits emergent properties.
Ex. Capillaries transport
blood (property not
exhibited by individual
endothelial cells).
2. Energy Use & Metabolism
Metabolism - biochemical reactions
that acquire & use energy.
Why do organisms need energy?
 to combat entropy
 to build new structures
 to repair/break down old structures
 to reproduce
How do organisms obtain energy?
3. Maintenance of Homeostasis
Homeostasis - the ability of an
organism to maintain its internal
environment despite conditions in
the external environment.
Ex. Human body temperature is ~98.6ºF
 if body temperature rises, you
sweat.
 if body temperature lowers, you
shiver.
4. Reproduction, Growth &
Development
Asexual reproduction - involves a
single parent; progeny are
genetically identical to the parent.
Sexual reproduction - involves 2
parents; progeny are genetically
diverse.
Is it essential for an individual to
reproduce?
5. Irritability & Adaptation
Irritability - immediate response to a
stimulus.
Adaptation - an inherited
behavior or characteristic
that enables an organism
to survive & reproduce.
Over time, adaptations are modified by
natural selection.
Natural Selection - the enhanced
survival & reproductive success of
individuals whose inherited traits
better adapt them to a particular
environment.
B. Biodiversity
Life on earth is diverse, yet similar.
Taxonomists place organisms into groups
based upon evolutionary relationships.
Broadest, most inclusive group (taxon) is
the domain.
Domain  Kingdom  Phylum or Division
 Class  Order  Family  Genus 
Species
Genus & species refer to the organism’s
binomial (name).
The Three Domains:
 Bacteria - unicellular prokaryotes
 Archaea - unicellular prokaryotes
 Eukarya - eukaryotes
 Kingdom
Protista
 Kingdom Plantae
 Kingdom Fungi
 Kingdom Animalia
Human classification scheme:
Domain
Kingdom
Phylum
Class
Order
Family
Genus & species
Eukarya
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo sapiens
C. The Study of Life
Scientists study life by using the
scientific method.
Observations, questions,
hypotheses as tentative
answers to questions
 Deductions leading to
predictions, and then tests of
predictions to see if a
hypothesis is falsifiable

Questions
or statements
that are testable
through experimentation
or observation
If - then format
Preliminary explanation
to problem
Scientific Method
Collaborate
Share
info
 Build upon other
work
1.
Scientific Method
Observe
2.
Define problem or
question
3.
Form a hypothesis
4.Test hypothesis with a
controlled
experiment
Scientific Method
5.
Observe and record
results
6.
Form conclusions by
confirming or
modifying the hypothesis
7.
Report Results
Observations
Question
Hypothesis # 1:
Dead batteries
Hypothesis # 2:
Burnt-out bulb
Prediction:
Replacing batteries
will fix problem
Prediction:
Replacing bulb
will fix problem
Test prediction
Test falsifies hypothesis
Test prediction
Test does not falsify hypothesis
Experiment
isolates a
single factor that is
directly responsible for
an effect.
Condition
in the
experiment that
differs
Independent
Variable:
Variable that is independent
of experiment
pH, time, temperature
Dependent Variable:
What you are testing
Dependent of results of
experiment
Provides
a standard of
comparison for the one
factor in the
experiment that varies
What is difference between
hypothesis, theory & law?
 Hypothesis
- “an educated guess”; a
tentative explanation of phenomena.
 Theory - a widely accepted explanation
of natural phenomena; has stood up to
thorough & continual testing.
 Law - a statement of what always
occurs under certain conditions.