Download Chapter 1: An introduction to Life on Earth

Introduction to Biology
BIOS 1010 7A
Sarah Jeffers
Biology: Life on Earth, 9e
Copyright © 2011 Pearson Education Inc.
Chapter 1
Introduction to Life on Earth
Biology: Life on Earth, 9e
Copyright © 2011 Pearson Education Inc.
Levels of Organization of Matter
& Species
Fig. 1-1
Biology: Life on Earth, 9e
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What Are The Characteristics of Living Things?
 Living things are
composed of cells
– Living things are both
complex and organized
Fig. 1-8
Biology: Life on Earth, 9e
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The Cell Is the Smallest Unit of Life
Fig. 1-2
Biology: Life on Earth, 9e
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The Cell Is the Smallest Unit of Life
• A characteristic of all living things is organization.
• Thus the name of all living things as organisms.
•All organisms consist of one or more cells
•The cell is the simplest structural and functional unit of life.
•Cells are the building blocks of all
•plants and animals.
•All new cells come from the division
•of pre-existing cells.
•Nutrients
•Division
•Cell
•Cells are the smallest units that perform
•all vital physiological functions.
•O2
•Wastes
•CO2
•Growth
•New
•cells
•The cell theory
Biology: Life on Earth, 9e
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The Domains and Kingdoms of Life
The “Tree of Life”
Fig. 1-11
Biology: Life on Earth, 9e
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How Do Scientists Categorize the Diversity of Life?
 Categorizing life
– There are exceptions to any simple set of rules used to
distinguish the domains and kingdoms, but three
characteristics are particularly useful
– Cell type
– The number of cells in each organism
– Energy acquisition
Biology: Life on Earth, 9e
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How Do Scientists Categorize the Diversity of Life?
 Classification into a domain or kingdom is based on
3 characteristics:
1. Cell type
•Bacteria
•Archaea
Biology: Life on Earth, 9e
•Eukarya
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How Do Scientists Categorize the Diversity of Life?
 Classification into a domain or kingdom is based on
3 characteristics:
2. Number of cells
•Bacteria
•Archaea
Biology: Life on Earth, 9e
•Eukarya
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How Do Scientists Categorize the Diversity of Life?
 Classification into a domain or kingdom is based on
3 characteristics:
3. Energy Acquisition
Autotroph
Self-feeding
Photosynthesis
Plants,
some Archaea
some Bacteria
some Protists
Biology: Life on Earth, 9e
vs.
Heterotroph
Other-feeding
Digest external food
Fungi,
Archaea
Bacteria
Animals
some Protists
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How Are Organisms Named And Classified?
 Taxonomy – naming and classifying organisms
– Scientific name: two part Latin name
– Genus (closely related species)
– species (populations that can interbreed)
Biology: Life on Earth, 9e
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How Are Organisms Named And Classified?
 Taxonomy – naming and classifying organisms
– Scientific name: two part Latin name
– Examples: Sialia (Bluebirds)
Sialia sialis
(eastern)
Biology: Life on Earth, 9e
Sialia mexicana
(western)
Sialia currucoides
(mountain)
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How Are Organisms Named And Classified?
 Phylogeny – evolutionary history
– Similarities from a common ancestor
– Not similarities from convergent evolution
– Phylogenic trees
Biology: Life on Earth, 9e
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Biology: Life on Earth, 9e
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Review Questions
1. List the three precepts of the cell theory.
2. Can you describe the levels of biological
organization?
3. Can you name and briefly describe the three
domains of life?
4. Can you explain how scientists discovered that
prokaryotes fall into two domains?
5. Can you explain how scientists name and categorize
diverse forms of life?
6. Can you explain why phylogenetic classifications
sometimes change?
Biology: Life on Earth, 9e
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•What is Science?
 Historical approaches to studying life
– The belief that some events happen through supernatural
forces (e.g., the actions of Greek gods)
– The belief that all events can be traced to natural causes
that we can comprehend (natural causality)
– Corollary: Evidence gathered from nature has not
been deliberately distorted to fool us
Biology: Life on Earth, 9e
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What is Science?
 Scientific principles underlie all scientific inquiry
– Natural causality is the principle that all events can be
traced to natural causes
– Natural laws apply to every time and place
– Scientific inquiry is based on the assumption that people
perceive natural events in similar ways
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What is Science?
 The scientific method is the basis for scientific
inquiry
–
–
–
–
–
–
Observation
Question
Hypothesis
Prediction
Experiment or Observation
Conclusion
Biology: Life on Earth, 9e
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What is Science?
 The scientific method
1. Observation of a specific phenomenon
2. The observation, in turn, leads to a question
3. The question leads to formulation of a hypothesis,
based on previous observations, that is offered as an
answer to the question
4. The hypothesis leads to a prediction, typically
expressed in “if…then…” language
5. The prediction is tested by carefully controlled
manipulations called experiments
6. The experiments produce results that either support or
refute the hypothesis, allowing the development of a
conclusion
Biology: Life on Earth, 9e
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What is Science?
 The scientific method
– Scientific experimentation tests the assertion that a
single variable causes a particular observation
– Controls are incorporated into experiments
– Controls keep untested variables constant
Biology: Life on Earth, 9e
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The Scientific Method
Fig. 1-4
Biology: Life on Earth, 9e
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The Experiments of Francesco Redi
Fig. E1-1
Biology: Life on Earth, 9e
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The Experiments of Malte Andersson
Fig. E1-2
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The Scientific Method
 Limitations of the scientific method
– One can never be sure all untested variables are
controlled
– Conclusions based on the experimental data must
remain tentative
Biology: Life on Earth, 9e
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The Scientific Method
 Communication is crucial to science
– Results of experimentation must be communicated
thoroughly and accurately to other scientists for repetition
– Repetition by other scientists add verification that
findings can be used as the basis for further studies
Biology: Life on Earth, 9e
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The Scientific Method
 Science can be accidental
– In the 1920s, bacteriologist Alexander Fleming grew
bacteria in cultures
– One of the bacterial cultures became contaminated with
a mold(Penicillium)
– Fleming nearly destroyed the culture when he noticed the
mold Fleming hypothesized that the mold produced an
antibacterial substance
Biology: Life on Earth, 9e
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Scientific Theory
 What does Scientific theory mean?
– A scientific theory differs in definition from that of
everyday usage
– Many people use the word theory to mean hypothesis,
or an “educated guess”
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Scientific Theory
– A scientific theory is a general explanation for important
natural phenomena
– It is extensively and reproducibly tested
– If compelling evidence arises, a theory may be
modified
– Described as a natural law
– New scientific evidence may prompt radical revision of
existing theory
– For example, the discovery of prions
Biology: Life on Earth, 9e
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Scientific Theory
 The discovery of prions
– Before 1980, all known infectious diseases contained
DNA or RNA
– In 1982, Stanley Prusiner showed that the infectious
sheep disease scrapie is caused by a protein (a “protein
infectious particle,” or prion)
– Prions have since been shown to cause “mad cow
disease” and diseases in humans
– The willingness of scientists to revise accepted belief in
light of new data was critical to understanding and
expanding the study of prions
Biology: Life on Earth, 9e
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