Chapter One Themes in the Study of Life

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Chapter OneThemes in the Study of Life
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Characteristics of Life

• Life cant be summed up into
• a simple, one-sentence explanation
• How do you know that a tree is alive and a rock
  is not?
• All living organisms share certain
  characteristics
• Do you remember what some of these are?
• Reproduce Contain DNA
• Adapt to environment Grow and develop
• Made up of cells Have definite lifespan
• Utilizes energy Responds to stimuli

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Levels of life

• Life is organized into many structural levels.
• Biological structural levels build upon the level
  below it
• cells ?
• tissues ?
• organs ?
• systems ?
• Individual organism ?
• populations ?
• communities ?
• ecosystems ?
• Biosphere
• And cells of course are made up from even
  smaller parts.

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Each Level of Biological Organization Has
Emergent Properties Continued

• Order is all around us. Notice the pattern and
  order in this sunflower.
• Emergent properties within these levels manifest
  themselves as a result of dynamic and unique
  interactions between components

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Understanding Biological Organization and its
Many Levels is Fundamental to the Study of Life

• Scientists cannot fully explain a higher level of
  order from a critical analysis of it parts-
• For example what good is the handle of a hammer
  without the head?
• Holism disrupting a living system interferes
  with the meaningful explanation of its processes
• But, biological structural levels build upon the
  level below it, so scientists cannot critically
  analyze living systems without taking them apart
• Reductionism reducing complex systems to
  simpler components that are more manageable to
  study

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Cells are an Organisms Basic Units of Structure
and Function

• The Cell Theory all living things consist of
  cells cells come from other cells
• Prokaryotic cells bacteria / NO true nucleus
• Eukaryotic cells all other organisms /
  membrane- bound nucleus and endomembrane system

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• In order for a species to continue, organisms
  must reproduce. DNA makes it possible for the
  heritable information to be passed on.
• DNA - deoxyribonucleic acid
• Encoded biological instructions
• Substance of genes
• Units of inheritance
• DNA structure
• Long chain made of four nucleotides
• Adenine, cytosine, guanine, and thymine
• Specific sequential arrangements encode the
  precise information in a gene

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Structure and Function are Found at all Levels

• DNA encodes a message which dictates the growth
  and development of the organism
• Each cell, organelle, organ, etc. has its own
  function or duty to perform.
• In multicellular organisms, genes are turned on
  or off in order to specialize the functions of
  the cells
• Form fits function
• Analyzing a biological structure clues us to what
  it does and how it works
• Knowing function of a structure provides insight
  about its construction

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Understand your subject or specimen

• Cells may be the units of organisms but it is the
  organism that is the unit of life
• It is not enough to merely learn what parts make
  up an organism, but how it grows, interacts,
  lives, and responds.
• Questions to ask about any organism to be
  studied
• What kind of organism is it?
• Where does it live?
• How does it acquire nutrients and other resources
  from the environment?
• How is the organism equipped for its way of life?

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Diversity and Unity

• Nearly 2 million species of living things have
  been identified, but it is estimated there are
  between 5 - 30 million total species on Earth
• 260,000 plants
• 50,000 animals
• 750,000 insects
• Everything has its own niche and purpose in life
  (diversity and uniqueness), but every living
  creature needs interaction and support to serve a
  greater purpose (unity)

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Taxonomy

• With so many types of organisms, a system of
  classification was necessary
• Carolus Linnaeus
• Bionomial nomenclature
• Taxonomy - naming and classifying species
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

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Figure 22-1(1)Page 422
KINGDOM
Animalia
PHYLUM
Chordata
CLASS
Mammalia
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Figure 22-1(2)Page 422
ORDER
Carnivora
FAMILY
Felidae
GENUS
Felis
SPECIES
Felis catus
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6 Kingdom vs. Domains

• The six kingdom system of taxonomy categorizes
  organisms based on cell structure and nutrition
• The domain system on the other hand is based on
  molecular differences
• There are 3 domains
• Domain Archaebacteria - contains the archaea
  kingdom
• Domain Eubacteria - contains the eubacteria
  kingdom
• Domain Eukarya - contains kingdoms animalia,
  protista, fungi, and plantae
• Phylogeny will be discussed when we get to
  evolution unit

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Figure 22-2Page 423
Domain Eubacteria (bacteria)
Domain Archaea
Domain Eukarya
The three domains
Common ancestor of all living organisms
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Kingdoms

• There are 6 Kingdoms
• Archaea - extreme bacteria more related to
  euks
• Eubacteria (Monera) - typical bacteria
  prokaryotic peptidoglycan cell walls
• Protista - single-celled, aquatic, euk
• Fungi - multi-celled euk, decomposers
• Plantae - photosynthetic euk multi-celled
• Animalia - consumers euk multi-celled 9
  phyla

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Figure 22-3Page 424
Eubacteria
Archaebacteria
Protista
Plantae
Protista
Animalia
Fungi
Common ancestor of all eukaryotes
The six-kingdom system of classification
Common ancestor of all living organisms
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Bacteria

• Well study in depth during microbiology and DNA
  technology

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Protista

• Protists produce 70 of our oxygen, but not all
• of them are photosynthetic
• Vary in size, structure, mode of locomotion, and
  reproduction
• Endosymbiont Theory the accepted belief is that
  mitochondria and chloroplasts originated from
  symbiotic relationships between early protists
  and bacteria
• Chloroplasts - from photosynthetic prokaryotes
• Mitochondria - from aerobic prokaryotes

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• Divided into 8 major groups
• Excavates, opisthokonts, discicristates,
  alveolates, heterokonts, cercozoa, amoebozoa, and
  plants
• NO- you dont need to memorize these
• The plant category also includes plants and algae
• Opisthokonts include members of the animal
  kingdom and fungi kingdom as well
• too confusing of a system

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Fungi

• Most are filamentous made up of hyphae forming
  an aggregation called mycelium
• Most have cell walls of chitin
• Most produce by spores (produced sexually or
  asex)
• 5 phyla are identified (but only 4 true phyla
  exist)
• Chytridiomycetes (most primitive) -only fungi
  with flagella
• Zygomycetes - black bread molds
• Ascomycetes - sac fungi (yeasts, mildews, colored
  molds, morels and truffles)
• Basidiomycetes - mushrooms, rust, smut, and puff
  balls

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• Some fungi play an important ecological role
• Mycorrhizae - a type of fungus which decomposes
  organic material in soil
• Benefit plants by increasing their absorptive
  surface area
• Roots supply fungus with sugars, amino acids, and
  other organic substances
• Scientists have measured movement of organic
  materials from one tree species to another

without
with
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Plants

• Youll learn everything you ever wanted to know
  about plants before we do photosynthesis in a few
  weeks.

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Animalia

• Animals can be classified according to
• body symmetry - radial or bilateral symmetry or
  asymmetrical
• body cavities coelomates, acoelomates,
  pseudocoelomates
• Coelom a fluid-filled cavity lined with
  mesoderm
• evolutionary relationships based on molecular
  data (DNA, rRNA, and Hox genes)

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Animal Phyla

• 1. Porifera - sponges
• Aquatic, mostly marine, typically asymmetrical,
  multicellular but do not have tissues,
  regenerative capabilities
• 2. Cnidarians - hydras, anemones, coral,
  jellyfish
• Radially symmetrical, stinging cells called
  nematocysts
• Diploblastic (only 2 germ layers)

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Animal Phyla

• Acoelomates
• 3. Platyhelminthes - flatworms (flukes,
  tapeworms)
• No body cavity, bilaterally symmetrical, simple
  nervous system with ganglia
• Triploblastic (endoderm, mesoderm, ectoderm)

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Animal Phyla

• Pseudocoelomates
• 4. Nematodes - round worms (hookworms, pinworms,
  Trichina)
• All parasitic, lack a circulatory system, covered
  by cuticle, false body cavity between mesoderm
  and endoderm
• Triploblastic (endoderm, mesoderm, ectoderm)

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Animal Phyla

• Coelomates
• I - Protostomes
• 5. Molluska - squid, snails, clams, oysters
• Soft body (usually covered with a shell), foot
  for locomotion, visceral mass contains body
  organs, reduced coelom, mantle secretes shell (if
  present), open circulatory system (except in
  cephalopods - octopus, squid, nautilus),
  triploblastic
• 6. Annelida - segmented worms (earthworm leech)
• Segmentation, setae, closed
• circulatory system, triploblastic

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Animal Phyla

• Coelomates
• I - Protostomes
• 7. Arthropoda - crustaceans, trilobites,
  centipedes, arachnids, insects
• Exoskeletons, paired, jointed appendages, open
  circulatory system, nervous system of brain,
  ladder-like nerve cords and often compound eyes
• Aquatic arthropods have gills while terrestrial
  arthropods have book lungs or trachea
• Triploblastic (endoderm, mesoderm, ectoderm)

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Animal Phyla

• Coelomates
• II - Deuterostomes
• 8. Echinodermata - sea stars, sea lilies,
  crinoids, sand dollars
• Larval stage is bilaterally symmetrical and adult
  form is radially symmetrical
• Nerve net, no excretory organs, endodermis,
  calcareous plates covered by epidermis, tube feet
• Triploblastic (endoderm, mesoderm, ectoderm)

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Animal Phyla

• Coelomates
• II - Deuterostomes
• 9. Chordata - vertebrates and invertebrates
• At some point in life cycle, all chordates have
• Notochord (flexible supporting rod), dorsal
  hollow nerve cord, pharyngeal slits, and post
  anal tail
• Coelomates with bilateral symmetry, endoskeleton,
  closed circulatory system with ventral heart
• Triploblastic (endoderm, mesoderm, ectoderm)

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Animal Phyla

• A closer look at vertebrates
• 2 pairs of appendages, closed circulatory system
  with ventral heart, vertebral column of bone or
  cartilage, anterior cranium, paired kidneys,
  complete digestive tract with large digestive
  glands
• Divided into 3 classes of fish (osteichthyes,
  chondrichthyes, agnatha) and 4 classes of
  tetrapods (amphibians, reptiles, birds, mammals)

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Germ Layers

• Weve used the term triploblastic, but what does
  it mean?
• 3 germ or embryonic layers
• Ectoderm - becomes outer covering and nervous
  sytem
• Mesoderm - becomes most internal organs
• Endoderm - becomes lining of the gastrointestinal
  tract

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Quantifying Biology

• Biology is the study of any and/or all of these
  living organisms we just mentioned
• Biology does not only involve observations, but
  includes quantifying, manipulating, and analyzing
  data in order to draw conclusions
• Review the Scientific Method
• Observations, Problem/Question, Hypothesis,
  Experiment and Data Collection, Analysis and
  Conclusions, Repetition and Sharing
• Lets focus briefly on manipulating and
  interpreting data

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Data Collection

• All data collected should be accurately measured
  or counted
• Should also be recorded carefully and neatly
• Data tables should be done with ruled lines and
  with appropriate titles and units

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Statistical Analysis

• Correctly manipulating data enables scientists to
  demonstrate significance of data and to validate
  claims
• When you learn of a claim that a scientist is
  making, dont you want to know what the
  supporting data is?

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Statistics Terminology

• Mean arithmetic average (sensitive to outlying
  data)
• Median the value that splits the number of data
  entries in half (not sensitive to outlying data)
• Range the spread of the data from least to
  greatest
• Standard deviation a calculated value
  indicating how much the data varies around the
  mean value
• Error bar vertical reference lines on graphical
  distribution of data that illustrates points of
  std deviations

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• To calculate Standard Deviation manually
• Take EACH data point and subtract the mean value
• Square each of these values and add them up
• Divide this sum by (the number of data entries
  minus 1)
• Then, take the square root of the answer
• The result is the Standard Deviation and is
  denoted with a /- sign because it falls on
  either side of the mean value

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• Standard Deviation using the TI Calculators
• Hit ltSTATgt and lt1gt to get to the lists screen
• In the L1 column, enter your data
• Hit ltSTATgt again
• Choose CALC and then 1-Var Stats
• Hit ltENTERgt
• It gives you the mean, the sum of the values, the
  sum of the squared differences, and the standard
  deviation (Sx)
• (If you scroll down, it also gives you the min
  and maximum values and the median)

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• t-test a test used to deduce the significance
  of the difference between two sets of data
• On your TI Calculator
• Hit ltSTATgt and ltEDITgt to enter your lists in
  column L1 and column L2
• Hit ltSTATgt again and scroll over to ltTESTSgt
• Choose lt4gt for two sample T test
• Make sure the two column heading appear from your
  data
• Scroll down and choose calculate
• The t value and df (degrees of freedom) are given
• Now, use your table to determine acceptance

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Correlation

• When a correlation exists between two sets of
  data, this does not establish that there is a
  causal relationship between the two variables
  being examined