Transcript 01 View of Life - Tracy Jubenville Nearing

Lecture 1
A View of Life
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Define: metabolism, homeostasis, heredity,
species, natural selection, evolution, ecology
Outline and describe the properties of life.
Describe evolution and its importance.
Define and list, in order, the levels of
organization from the simplest to the most
complex.
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Objectives
•Compare and contrast the flow of energy and
materials through an ecosystem.
•List some ways in which human activities are
modifying ecosystems
•Explain how and why taxonomists classify
organisms.
•List the stages of the scientific process and
explain how these steps are used. Note the use
of controlled studies.
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Living things:
◦ Comprised of the same chemical elements e.g. Carbon,
Hydrogen, and Oxygen
◦ Obey the same physical and chemical laws
◦ Living organisms consist of cells (Unicellular or Multicellular).
 The cell is the basic structural and functional unit of all living
things e.g. plants, animals, and fungus
 Cells are produced from preexisting cells
 Cells are the smallest units that perform all vital physiological
functions
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Living organisms can be Microscopic:
Bacteria
Paramecium
Living organisms can be Macroscopic (Multi-cellular):
Snow goose
Humans
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Bacteria
Paramecium
Morel
Sunflower
Snow goose
(Bacteria): © Dr. Dennis Kunkel/Phototake; (Paramecium): © M. Abbey/Visuals Unlimited; (Morel): © Royalty-Free Corbis;
(Sunflower): © Photodisc Green/Getty Images; (Snow goose): © Charles Bush Photography
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Each level of organization has Emergent Properties
Levels range from extreme micro (e.g. Atoms,
Molecules and Cells) to global (e.g. Community,
Ecosystem and Biosphere)
Each level of organization is more complex than the
level preceding it
◦ Emergent properties:
 Interactions between the parts making up the whole
 All emergent properties follow the laws of physics and chemistry
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Biosphere
Regions of the Earth’s crust,
waters, and atmosphere
inhabited by living things
Ecosystem
A community plus
the physical environment
Community
Interacting populations in a
particular area
Population
Organisms of the same
species in a particular area
Organism
An individual; complex
individuals contain organ systems
Organ System
Composed of several organs
working together
Organ
Composed of tissues functioning
together for a specific task
Tissue
A group of cells with a common
structure and function
Cell
The structural and functional
unit of all living things
Molecule
Union of two or more atoms of
the same or different elements
Atom
Smallest unit of an element composed of
electrons, protons, and neutrons
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Energy – required to maintaining organization and
conducting life-sustaining processes
◦ The sun:
 Ultimate source of energy for nearly all life on Earth
 Certain organisms, such as plants, capture solar energy to
carry on photosynthesis
 Photosynthesis transforms solar energy into chemical energy (Organic
Molecules)
 Chemical energy is used by other organisms e.g. animals
◦ Metabolism is all the chemical reactions that occur in a cell
or in an organism.
 Homeostasis - Maintenance of internal conditions within certain
boundaries
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Living things interact with the environment and
respond to changes in the environment
Response ensures survival of the organism and it
often results movement
◦ Vulture can detect and find carcass a mile away and soar
toward dinner
◦ Monarch butterfly senses approach of fall and migrates
south
◦ Microroganisms can sense light or chemicals
◦ Even leaves of plants follow sun
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Activities as a result of Responses are termed
behavior
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Organisms live and die
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All living organisms must reproduce to ensure
continued existence and maintain population
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In most multicellular organisms reproduction:
◦ Begins with union of sperm and egg (fertilization)
◦ Followed by cell division and differentiation
◦ Developmental instructions encoded in genes
 Composed of DNA
 Long spiral molecule in chromosomes
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Adaptation
◦ Any modification that makes an organism more
suited to its way of life
◦ Organisms become modified over long period time
 Respond to environmental changes by developing new
adaptations
◦ However, organisms very similar at basic level
 Suggests living things descended from same ancestor
 Descent with modification - Evolution
 Caused by natural selection
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Despite diversity, organisms share the same
basic characteristics
◦ Composed of cells organized in a similar manner
◦ Their genes are composed of DNA
◦ Carry out the same metabolic reactions to acquire
energy
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This suggests that they are descended from
a common ancestor
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Taxonomy:
◦ Discipline of identifying and classifying organisms
according to certain rules
◦ Hierarchical levels (taxa) based on hypothesized
evolutionary relationships
◦ Levels are, from least inclusive to most inclusive:
 Species, genus, family, order, class, phylum, kingdom, and
domain
 A level (e.g. phylum) includes more species than the level
below it (e.g. class), and fewer species than the one above
it (e.g. kingdom)
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Bacteria
◦ Microscopic unicellular prokaryotes
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Archaea
◦ Bacteria-like unicellular prokaryotes
◦ Extreme aquatic environments
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Eukarya
◦ Eukaryotes – Familiar organisms
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BACTERIA
common
ancestor
(first cells)
ARCHAEA
Protists
Photosynthetic
protist
Plants
cell with nucleus
EUKARYA
Fungi
Heterotrophic
Protist
Animals
common ancestor
Past
Present
Time
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• Prokaryotic cells
of various shapes
• Adaptations to
extreme environments
• Absorb or
chemosynthesize food
• Unique chemical
characteristics
Methanosarcina mazei, an archaeon
1.6
m
© Ralph Robinson/Visuals Unlimited
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• Prokaryotic cells
of various shapes
• Adaptations to
all environments
• Absorb, photosynthesize,
or chemosynthesize food
• Unique chemical
characteristics
Escherichia coli, a bacterium
1.5
m
© A.B. Dowsett/SPL/Photo Researchers, Inc.
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Archaea – Kingdoms still being worked out
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Bacteria - Kingdoms still being worked out
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Eukarya
◦ Kingdom Protista
◦ Kingdom Fungi
◦ Kingdom Plantae
◦ Kingdom Animalia
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Protists
KINGDOM: Plants
1
m
• Algae, protozoans,
slime molds, and
water molds
• Complex single cell
(sometimes filaments,
colonies, or even
multicellular)
• Absorb, photosynthesize,
or ingest food
• Certain algae, mosses, ferns,
conifers, and flowering plants
• Multicellular, usually with
specialized tissues,
containing complex cells
• Photosynthesize food
r
Paramecium, a unicellular protozoan
KINGDOM: Animals
KINGDOM: Fungi
• Sponges, worms, insects,
fishes, frogs, turtles,
birds, and mammals
• Multicellular with
specialized tissues
containing complex cells
• Ingest food
• Molds, mushrooms, yeasts,
and ringworms
• Mostly multicellular filaments with
specialized, complex cells
• Absorb food1
Coprinus, a shaggy mane mushroom
Vulpes, a red fox
(Protist): © Michael Abby/Visuals Unlimited; (Plant): © Pat Pendarvis; (Fungi): © Rob Planck/Tom
Stack; (Animal): © Royalty-Free/Corbis
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Binomial nomenclature (two-word names)used to assign each organism with two part
name e.g. Homo Sapience
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Universal
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Latin-based
◦ First word represents genus of organism e.g.
Homo
◦ Second word is specific epithet of a species within
the genus e.g. Sapience
◦ Always italicized as a Genus species (Homo
sapiens)
◦ Genus may be abbreviated e.g. Escherichia Coli as
E. Coli
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Some plants within a population exhibit variation in leaf structure.
Deer prefer a diet of smooth leaves over hairy leaves. Plants with
hairy leaves reproduce more than other plants in the population.
Generations later, most plants within the population have hairy
leaves, as smooth leaves are selected against.
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Population - Members of a species within an
area
Community - A local collection of interacting
populations
Ecosystem – A community plus its physical
environment
 How chemicals are cycled and re-used by organisms
 How energy flows, from photosynthetic plants to top
predators
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heat
solar
energy
heat
heat
heat
heat
heat
WASTE MATERIAL, DEATH,
AND DECOMPOSITION
Chemical cycling
Energy flow
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a. Healthy coral reef
1975 Minimal coral death
b.
1985 Some coral death with
no fish present
1995 Coral bleaching with limited
chance of recovery
2004 Coral is black from sedimentation;
bleaching still evident
a: © Frank & Joyce Burek/Getty Images; b (All): © Dr. Phillip Dustan
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Humans modify ecosystems
◦ Humans negative impact on ecosystems:
 Destroy forest or grassland for agriculture, housing,
industry, etc.
 Produce waste and contaminate air, water, etc.
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However, humans depend upon healthy
ecosystems for
◦ Food
◦ Medicines
◦ Raw materials
◦ Other ecosystem processes
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Biodiversity is the zone of air, land, and
water where organisms exist
◦ Abundance of species estimated about 15 million.
◦ The variability of their genes, and
◦ The ecosystems in which they live
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Extinction is:
◦ The death of the last member of a species
◦ Estimates of 400 species/day lost worldwide
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Scientific method is a standard series of
steps in gaining new knowledge through
research.
◦ Begins with observation
 Scientists use their five senses e.g. use visual sense to
observe animal behavior
 Instruments can extend the range of senses e.g. use
microscope to see microorganisms
 Take advantage of prior studies
◦ Hypothesis
 A tentative explanation for what was observed
 Developed through inductively reasoning from specific to
general
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Observation
New observations
are made, and previous
data are studied.
Hypothesis
Input from various
sources is used to formulate
a testable statement.
Experiment/Observations
Conclusion
The hypothesis is
tested by experiment
or further observations.
The results are analyzed,
and the hypothesis is
supported or rejected.
Scientific Theory
Many experiments and
observations support a
theory.
Courtesy Leica Microsystems Inc.
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Experimentation
◦ Purpose is to challenge the hypothesis
◦ Designed through deductively reasoning from
general to specific
◦ Often divides subjects into a control group and an
experimental group
◦ Predicts how groups should differ if hypothesis is
valid
 If prediction happens, hypothesis is unchallenged
 If not, hypothesis is unsupportable
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The results are analyzed and interpreted
Conclusions are what the scientist thinks
caused the results
Findings must be reported in scientific
journals
Peers review the findings and the
conclusions
Other scientists then attempt to duplicate or
dismiss the published findings
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Results or Data
◦ Observable, objective results from an experiment
◦ Strength of the data expressed in probabilities
◦ The probability that random variation could have
caused the results
 Low probability (less than 5%) is good
 Higher probabilities make it difficult to dismiss random
chance as the sole cause of the results
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Scientific Theory:
◦ Joins together two or more related hypotheses
◦ Supported by broad range of observations,
experiments, and data
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Scientific Principle / Law:
◦ Widely accepted set of theories
◦ No serious challenges to validity
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Experimental (Independent) variable
◦ Applied one way to experimental group
◦ Applied a different way to control group
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Response (dependent) variable
◦ Variable that is measured to generate data
◦ Expected to yield different results in control versus
experimental group
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Observations:
◦ Nitrate fertilizers boost grain crops, but may
damage soils by altering its properties
◦ When grain crops are rotated with pigeon pea it
adds natural nitrogen
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Hypothesis:
◦ Pigeon pea rotation will boost crop production as
much as nitrates
◦ Pigeon pea rotation will NOT damage soils
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nodules
© Dr. Jeremy Burgess/Photo Researchers, Inc.
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Experimental Design
◦ Control Group
 Winter wheat planted in pots without fertilizer
◦ Experimental Groups
 1-Winter wheat planted in pots with 45 kg/ha nitrate
 2-Winter wheat planted in pots with 90 kg/ha nitrate
 3-Winter wheat planted in pots that had grown a crop
of pigeon peas
◦ All groups treated identically except for above
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Control pots
Test pots
Test pots
no fertilization treatment
90 kg of nitrogen/ha
Pigeon pea/winter wheat rotation
a. Control pots and test pots
of three types
Test pots
45 kg of nitrogen/ha
Wheat Biomass (grams/pot)
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Control Pots
= no fertilization treatment
Test Pots
= 45 kg of nitrogen/ha
= 90 kg of nitrogen/ha
= Pigeon pea/winter wheat rotation
10
5
0
year 1
year 2
year 3
b. Results
(All): Courtesy Jim Bidlack
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Experimental Prediction:
◦ Wheat production following pigeon pea rotation will
be equal or better than following nitrate fertilizer
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Results
◦ 45 kg/ha produced slightly better than controls
◦ 90 kg/ha produced nearly twice as much as controls
◦ Pigeon pea rotation did not produce as much as the
controls
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Conclusion
◦ Research hypothesis was not supported by results
◦ However, research hypothesis was not proven false
by negative results
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Revised experiment
◦ Grow wheat in same pots for several generations
◦ Look for soil damage in nitrate pots and improved
production in pigeon pea pots
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Results
◦ After second year:
 Production following nitrates declined
 Production following pigeon pea rotation was greatest of
all
◦ After third year
 Pigeon pea rotation produced 4X as much as controls
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Revised conclusions
◦ Research hypothesis supported
◦ Pigeon pea rotation should be recommended over
nitrates
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Defining Life - Emergent Properties
◦ Materials and Energy
◦ Reproduction and Development
◦ Adaptations and Natural Selection
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Biosphere Organization
◦ Human Population
◦ Biodiversity
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Classification
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The Scientific Method
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