Transcript You Light Up My Life

Concepts & Methods in
Biology
Chapter 1
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
 To understand issues of scientific research
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
Scientific Method
Science is a Process
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Observation
Research
Question
Hypothesis – Needs to be testable
Experiment
Results
Conclusion
Role of Experiments
 Used to study a phenomenon under known
conditions
 Allows you to predict what will happen as
long as the hypothesis is not wrong
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
Theory Vs. Scientific Law
 Theory is a hypothesis that has been
supported by many lines of evidence
 A law is a theory that has been supported
for a significant amount of time
 Can a theory ever be proven 100% correct?
Limits of Science
 Scientific approach cannot provide answers
to subjective questions
 Cannot provide moral, aesthetic, or
philosophical standards
 Can conflict with supernatural beliefs
What is Life?
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Organization
Reproduction – life comes from life
Growth and Development
Metabolism
Response to stimuli
Homeostasis
Adaptation
Hierarchy of Life
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Atoms – C,H,O,N = 96% of the dry weight
Molecules – major organic compounds
Cells – 2 cell types
Tissues
Organs
Organ systems
Organism
Ecological order – population, community, ecosystem
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 Guides Development
 Multicelled organisms develop
 Instructions for each stage of development
is 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
Photosynthesis and Cellular Respiration
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
Interdependencies among
Organisms
Producers –
Autotrophs
Make their own food
Consumers –
Heterotrophs
Depend on energy stored in tissues
of producers
Decomposers
Break down remains and wastes
Energy Flow
 Usually starts with energy from
The Sun
 Transfered 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 in metabolism
– Sense and respond to the environment
– Have 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
 Binomial Nomenclature
 First name is genus (Capitalized)
– Homo sapiens - genus is Homo
 Second name is species within genus (Lower
case)
 Always written either in italics or underlines
3 Domains
Eubacteria
(Bacteria)
Archaebacteria
(Archaea)
Eukaryota
(Eukaryotes)
6 Kingdoms
Protistans
Plants
Fungi
Animals
Eukaryotes
Archaebacteria
Eubacteria
Origin of life
Prokaryotic
Organisms
 Single cells
 No nucleus or
membrane bound
organelles
Eukaryotic
Organisms
 Single- or multicelled
 Nucleus and other
organelles
 Smaller, less complex  Larger, more
complex
Mutation: Source of Variation
 Mutation =
a change in the structure of DNA
 Basis for the variation in heritable traits
 Most are harmful, beneficial ones may lead to evolution
 Point, Frameshift, and Chromosomal
Adaptive Trait
A trait that gives the individual an advantage
in survival or reproduction, under a given set
of circumstances
Evolution
 Decent with modification
 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