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
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
DNA (deoxyribonucleic acid)
Signature molecule of life
Molecule of inheritance
Directs assembly of amino acids
DNA and Inheritance
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
Multicelled organisms develop
Series of stages
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
Organisms sense changes in their environment
and make responses to them
Receptors detect specific forms of energy
(stimuli)
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
Transfer from one organism to another
Energy flows in one direction
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
Millions of living species
Millions more now extinct
Classification schemes attempt to
organize diversity
Scientific Names
Devised by Carolus Linnaeus
First name is genus (plural, genera)
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
Single cells
Single- or multi-celled
No nucleus or
Nucleus and other
organelles
Smaller, less
complex
organelles
Larger, more complex
Mutation: Source of Variation
Mutation = change in structure of DNA
Basis for the variation in heritable traits
Most are harmful
Adaptive Trait
A trait that gives the individual an advantage in
survival or reproduction, under a given set of
circumstances
Evolution
Genetically based change in a line of descent
over time
Population changes, not individuals
Artificial Selection
Breeders are selective agents
Individuals exhibiting favored traits are bred
Favored traits become more common in
population
Natural Selection
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
Antibiotics are used to kill bacteria
Mutations for antibiotic resistance exist or arise
Antibiotic-resistant bacteria survive and
reproduce better than nonresistant
Over time, proportion of antibiotic-resistant
bacteria increases
Scientific Method
Observe phenomenon
Develop hypotheses
Make predictions
Devise test of predictions
Carry out test and analyze results
Inductive Logic
Using observations and facts to arrive at
generalizations or hypotheses
Observation: Eagles, swallows, and robins have
feathers
Hypothesis: All birds have feathers
Deductive Logic
Drawing a specific conclusion based on a
generalization
Generalization - Birds have feathers
Example - Eagles are birds
Conclusion - Eagles have feathers
Role of Experiments
Used to study a phenomenon under known
conditions
Allows you to predict what will happen if a
hypothesis is not wrong
Can never prove a hypothesis 100% correct
Experimental Design
Control group
A standard for comparison
Identical to experimental group except for variable
being studied
Sampling error
Nonrepresentative sample skews results
Minimize by using large samples
Scientific Theory
A hypothesis that has been tested for its
predictive power many times and has not yet
been found incorrect
Has wide-ranging explanatory power
Darwin’s theory of evolution by natural selection
Limits of Science
Scientific approach cannot provide answers to
subjective questions
Cannot provide moral, aesthetic, or
philosophical standards
Conflict with supernatural beliefs
Copernicus
Darwin
Scientists Raise Questions
The external world, not internal conviction,
must be the testing ground for scientific beliefs