Chapter 1 The Science of Biology

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Chapter 1The Science of Biology

• Biology is the science of life.

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1.1 Properties of Life

• 1. Cellular Organization.
• 2. Order.
• 3. Sensitivity.
• 4. Growth, development, and reproduction.
• 5. Energy utilization.
• 6. Evolutionary adaptation.
• 7. Homeostasis.

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1.1 Hierarchical Organization

• Cellular Level
• Atoms
• Molecules
• Macromolecules
• Organelles
• Cells

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1.1 Hierarchical Organization

• Organismal Level
• Cells
• Tissues
• Organs
• Organ Systems
• Organism

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1.1 Hierarchical Organization

• Population Level
• Organism
• Population
• Species
• Community
• Ecosystem
• Biosphere
• Emergent properties result from the way in which
  components interact and cannot be guessed just by
  looking at the parts themselves.

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1.2 The Nature of Science

• Deductive Reasoning (stem de down)
• Applies general principles to specific cases.
• Used to infer the species of a specimen from its
  characteristics
• fur, 4 legs, panting, canines ? dog
• Length of a shadow on solstice ? circumference of
  earth

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Eratosthenes geometrical calculation of the
circumference of the Earth

• Eratosthenes (276 - 195 B.C.)
• Eratosthenes used geometry to estimate the
  circumference of the Earth.
• Eratosthenes measured the altitude of the
  noontime sun at Alexandria at its maximum on Jun
  21st. On that date, the Sun is directly overhead
  at noontime at Syene, in southern Egypt (latitude
  23.5 degrees north). The zenith distance is
  the angle from the zenith to the point where the
  Sun was at noon it is also 90 degrees minus the
  altitude. At Syene, the zenith distance was 0
  degrees at Alexandria it was about 7 degrees.
  He knew how far it was from Alexandria to Syene
  (estimate 925 km actual 800 km), so he used
  geometry and the difference in zenith angle to
  estimate the size of the Earth (estimate
  46, 250 actual 40, 075).

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1.2 The Nature of Science

• Inductive Reasoning (stem in up)
• Applies specific observations to construct
  specific principles.
• Leads to generalizations that can be tested.
• Dogs have hair, cats have hair ? all mammals have
  hair
• Apples fall from your hand ? gravity

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1.2 Sir Isaac Newtons Apple

• In 1666, as tradition has it, Newton observed the
  fall of an apple in his garden at Woolsthorpe,
  later recalling, 'In the same year I began to
  think of gravity extending to the orb of the
  Moon.' Newton's memory was not accurate. In fact,
  all evidence suggests that the concept of
  universal gravitation did not spring full-blown
  from Newton's head in 1666 but was nearly 20
  years in gestation. Ironically, Robert Hooke
  helped give it life. In November 1679, Hooke
  initiated an exchange of letters that bore on the
  question of planetary motion. Although Newton
  hastily broke off the correspondence, Hooke's
  letters provided a conceptual link between
  central attraction and a force falling off with
  the square of distance. Sometime in early 1680,
  Newton apprears to have quietly drawn his own
  conclusions.

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How Science Is Done
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1.2 How Science is Done

• How Science Is Done
• Scientists make observations and then construct
  a suggested explanation (hypothesis) to account
  for those observations.
• A successful experiment rejects one or more
  alternative hypotheses.

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1.2 How Science is Done

• Often scientists will conduct two experiments in
  parallel. In one experiment, all the variables
  are kept constant except one, while in the other
  experiment, the control experiment, that variable
  is left unaltered.
• Predictions provide a way to test the validity of
  a hypothesis. If predictions are supported, the
  hypothesis is supported.

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1.2 How Science is Done

• Independent variable
• Chosen by scientist to test the hypothesis
• One variable that is changed in the experimental
  group
• Controlled variables
• All other variables are treated the same in both
  experimental and control groups
• Dependent variable(s)
• The outcome of the experiment (results)
• It is dependent on which independent variable was
  chosen

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1.2 How Science is Done

• A theory is a proposed explanation for some
  natural phenomenon.
• A theory is also used to refer to a body of
  interconnected concepts supported by scientific
  reasoning and experimental evidence.
• After developing a hypothesis and performing a
  series of experiments, a paper is written
  describing the experiment and the results the
  paper is then submitted for peer review.

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1.3 Darwin's theory of evolution illustrates how
science works.

• In Darwin's time, most people believed species to
  be specially created and unchangeable.
• Darwin proposed the concept of natural selection
  to account for his view that living things must
  have changed or evolved during their history on
  earth.
• Darwin served as naturalist on a five-year
  navigational mapping expedition around the coasts
  of South America.

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1.3 Darwin's theory of evolution illustrates how
science works.

• Darwin's Evidence
• Repeatedly, Darwin found that characteristics of
  similar species varied from place to place,
  suggesting that organismal lineages change
  gradually as species migrate, and that plants and
  animals on young volcanic islands resembled those
  on nearby coasts of South America.

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1.3 Charles Darwins voyage
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1.3 Darwins evidence

• 1. The Earth is old (helped by geologist, Charles
  Lyell) species were constantly becoming extinct,
  while new species were emerging
• 2. examining the fossil beds of South America
  Darwin saw that fossil organisms were similar to
  living organisms.
• He wondered how such similar organisms could
  occur in the same geographic area unless ancient
  ones gave rise to the modern form (Glyptodont and
  Armadillo)

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1.3 Darwins evidence

• 3. similar, yet slightly different
  species on each island of the Galapagos each
  adapted to its specific food source Darwins
  Finches must have had a common ancestor, he
  reasoned
• 4. there is competition for resources (helped by
  Thomas Malthus) species reproduce geometrically
  population increases by a constant factor
  (multiply) unless slowed by the slower rate of
  growth of available food. Food increases
  arithmetically.

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1.3 Darwins evidence

• Tomas Malthus theory of species growth 1798
• Population, when unchecked, increases in a
  geometrical ratio. Subsistence increases only in
  an arithmetical ratio. A slight acquaintance with
  numbers will shew the immensity of the first
  power in comparison of the second.
• By that law of our nature which makes food
  necessary to the life of man, the effects of
  these too unequal powers must be kept equal. This
  implies a strong and constantly operating check
  on population from the difficulty of subsistence.
  This difficulty must fall some where and must
  necessarily be severely felt by a large portion
  of mankind.

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1.3 Darwins evidence

• 5. Artificial selection (breeding) of pigeons
  showed that favorable characteristics can be
  selected although nothing was known about the
  mechanisms of inheritance (genetics). Darwin
  reasoned that wild populations also gain
  favorable characteristics for survival because of
  their competitive advantage (survival of the
  fittest idea is termed natural selection)
• Darwins theory provides a simple and direct
  explanation of biological diversity.

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1.3 Publication of Darwins Hypothesis

• 1842 Darwin drafted the overall argument for
  evolution by natural selection and showed it to
  select scientific friends
• 1858 Darwin receives an essay by Alfred Wallace
  outlining his own hypothesis of evolution by
  natural selection
• 1858 Darwin arranges for a joint presentation
  with Wallace on their ideas at a seminar in
  London
• 1859 Darwin published his book On the Origin
  of Species
• 1860s Darwins ideas are almost completely
  accepted by intellectual community in Great
  Britain

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1.3 Charles Darwin, On the Origin of Species
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1.3 Darwin's theory of evolution illustrates how
science works.

• Evolution after Darwin more evidence
• the increasingly complete fossil record
• intermediate links between groups of organisms
  have been found just as Darwin predicted fossil
  record now goes back 2.5 billion years fossils
  have gone from simple to more complex as Darwin
  predicted
• Radiometric dating
• (decay rates of radioactive elements indicates
  the age of the Earth is 4.5 billion years old

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1.3 Evolution after Darwin more evidence

• the discovery of heredity mechanisms--DNA
• comparative anatomy studies differentiating
  homologous
• bones of the forelimbs have a similar
  evolutionary origin, but differ in structure and
  function human, cat, bat, porpoise horse
• and analogous structures
• versus analogous structures similar structure
  and function but different evolutionary origins
  bird wing versus insect wing

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1.3 Evolution after Darwin more evidence

• molecular evidence
• comparing the genomes (sequences of all genes) of
  different groups of animals or plants we can see
  how closely these groups are related 2 species
  that are closely related will share a greater
  of unchanged DNA Hemoglobin is a protein in
  animals that is often used for this comparision

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1.3 Evolution after Darwin more evidence

• molecular clocks
• analysis of changes in a specific gene
  (cytochrome c) which changes at a constant rate
  works like a clock showing how recently similar
• groups diverged from one another
• phylogenetic trees
• the evolutionary history of a specific gene
  allows scientists to construct a family tree
  which shows how closely related one group of
  organisms is to every other group

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1.4 Four themes unify biology as a science.

• Core Themes Unite Biology
• The four themes uniting the field of biology are
  
• Organization of Life the Cell Theory
• The cell theory (all living organisms are
  composed of one or more cells) Robert Hooke
  discovered cells Anton van Leeuwenhoek (single
  celled life in pond water) cell theory developed
  by Matthias Schleiden and Theodor Schwann all
  cells come from other cells

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1.4 Four themes unify biology as a science.

• Core Themes Unite Biology
• Continuity of Life the Molecular Basis of
  Inheritance
• DNA contains the blueprint for life is made up
  of two chains of nucleotides wound around each
  other gene is a discrete unit of information
  for a particular protein or piece of RNA the
  proteins and RNA determine what a cell will be
  like Genome entire set of DNA that specifies a
  cell the human genome was decoded in rough form
  in 2001 (3 billion nucleotides long)

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1.4 Four themes unify biology as a science.

• Core Themes Unite Biology
• Diversity of Life Evolutionary Change
• Evolutionary Change a wide diversity of living
  organisms have evolved to fill the great variety
  of environments on Earth
• 3 great groups or domains (based on cell
  structure)
• Bacteria
• Archaea
• Eukarya domain divided into
  4 kingdoms
  
  Protista, Plantae,
  Fungi, Animalia

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1.4 Four themes unify biology as a science.

• Core Themes Unite Biology
• Unity of LifeEvolutionary Conservation
• Evolutionary Conservation conserved hereditary
  information stored in the DNA molecule is common
  to all living organisms Certain basic
  characteristics are shared throughout the animal
  kingdom
• ex chromosomes in the nucleus and flagellae have
  the exact same microtubule arrangement throughout
  the animal kingdom