Transcript Chapter 1

Concepts & Methods
in Biology
Chapter 1
Biology
Scientific study of life
Lays the foundation
for asking basic questions about life
and the natural world
Why Study Biology?

To learn how organisms are constructed, how
they function, where they live, and what they do

To help develop, modify, and refine ideas about
life
Molecules of Life
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All things are made up of the same units of
matter
Living things are made up of a certain subset of
molecules:
Nucleic acids
 Proteins
 Carbohydrates
 Lipids
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DNA (deoxyribonucleic acid)

Signature molecule of life
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Molecule of inheritance
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Directs assembly of amino acids
DNA and Inheritance
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Inheritance
 Acquisition of traits by way of transmission
of DNA from parent to offspring
Reproduction
 Mechanism by which an organism produces
offspring
 Governed by instructions in DNA
DNA Guides Development
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Multicelled organisms develop
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Series of stages
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Instructions for each stage in DNA
Nothing Lives without Energy
Energy = Capacity to do work
Metabolism = Reactions by which
cells acquire and use energy to
grow, survive, and reproduce
Sensing and Responding
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Organisms sense changes in their environment
and make responses to them
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Receptors detect specific forms of energy
(stimuli)
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Allows maintenance of homeostasis
Levels of Organization
Cell
Multicelled Organism
Population
Community
Ecosystem
Biosphere
Interdependencies among
Organisms
Producers
Make their own food
Consumers
Depend on energy stored in tissues
producers
Decomposers
Break down remains and wastes
of
Energy Flow

Usually starts with energy from sun
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Transfer from one organism to another
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Energy flows in one direction
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Eventually, all energy flows back to the
environment
ENERGY FROM
SUN
Producers
NUTRIENT
CYCLING
Consumers,
Decomposers
ONE-WAY FLOW
OF ENERGY
In time, all energy
flows back to the
environment.
Unity of Life
All organisms:
 Are
composed of the same substances
 Engage
 Sense
 Have
in metabolism
and respond to the environment
the capacity to reproduce based on
instructions in DNA
Diversity of Life
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Millions of living species
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Millions more now extinct
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Classification schemes attempt to
organize diversity
Scientific Names
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Devised by Carolus Linnaeus
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First name is genus (plural, genera)
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Homo sapiens - genus is Homo
Second name is species within genus
3 Domains
Eubacteria
(Bacteria)
Archaebacteria
(Archaea)
Eukaryota
(Eukaryotes)
6 Kingdoms
Protistans
Plants
Fungi
Animals
Eukaryotes
Archaebacteria
Eubacteria
Origin of life
Prokaryotic
Organisms
Eukaryotic
Organisms
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Single cells
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Single- or multi-celled
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No nucleus or

Nucleus and other
organelles
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Smaller, less
complex
organelles
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Larger, more complex
Mutation: Source of Variation
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Mutation = change in structure of DNA
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Basis for the variation in heritable traits
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Most are harmful
Adaptive Trait
A trait that gives the individual an advantage in
survival or reproduction, under a given set of
circumstances
Evolution
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Genetically based change in a line of descent
over time
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Population changes, not individuals
Artificial Selection
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Breeders are selective agents
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Individuals exhibiting favored traits are bred
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Favored traits become more common in
population
Natural Selection
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Individuals vary in some heritable traits
Some forms of heritable traits are more adaptive
Natural selection is differences in survival and
reproduction among individuals that vary in
their traits
Adaptive forms of traits become more common
than other forms
Antibiotic Resistance
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Antibiotics are used to kill bacteria
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Mutations for antibiotic resistance exist or arise
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Antibiotic-resistant bacteria survive and
reproduce better than nonresistant
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Over time, proportion of antibiotic-resistant
bacteria increases
Scientific Method
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Observe phenomenon
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Develop hypotheses
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Make predictions
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Devise test of predictions
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Carry out test and analyze results
Inductive Logic
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Using observations and facts to arrive at
generalizations or hypotheses
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Observation: Eagles, swallows, and robins have
feathers
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Hypothesis: All birds have feathers
Deductive Logic

Drawing a specific conclusion based on a
generalization
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Generalization - Birds have feathers
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Example - Eagles are birds
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Conclusion - Eagles have feathers
Role of Experiments
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Used to study a phenomenon under known
conditions
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Allows you to predict what will happen if a
hypothesis is not wrong
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Can never prove a hypothesis 100% correct
Experimental Design
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Control group
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A standard for comparison
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Identical to experimental group except for variable
being studied
Sampling error
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Nonrepresentative sample skews results
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Minimize by using large samples
Scientific Theory
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A hypothesis that has been tested for its
predictive power many times and has not yet
been found incorrect
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Has wide-ranging explanatory power
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Darwin’s theory of evolution by natural selection
Limits of Science
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Scientific approach cannot provide answers to
subjective questions
Cannot provide moral, aesthetic, or
philosophical standards
Conflict with supernatural beliefs
Copernicus
 Darwin
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Scientists Raise Questions
The external world, not internal conviction,
must be the testing ground for scientific beliefs