Biology Chapter 17

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Biology Chapter 17

• Evolution
• The History of Life

More than ______ of all species that have ever
lived on Earth have become extinct.

99.9
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17-1 The Fossil Record

• I. Fossils and Ancient Life
• A. _______________ are scientists who study
  fossils.
• B. The fossil record _________ evidence about
  the history of life on Earth. It also shows how
  different __________ _____________, including
  species, have changed over time.

Paleontologists
provides
groups
of organisms
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II. How Fossils Form

• A. For a fossil to form, either the _________
  ___________ or some trace of its presence must
  be preserved.
• 1. A precise _________________ must be present
  to form a fossil.
• 2. The fossil record provides ____________
  ____________ about the history of life.

remains of the organism
set of conditions
incomplete information
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sedimentary rock.

• B. Most fossils are formed in ___________
  _______.
• 1. Sedimentary rock forms from the
• _________________________________
• 2. These particles are carried by _________
  ___________ into lakes or seas, where they
  eventually settle to the bottom.

erosion of rock into sand, silt, and clay.
streams and rivers
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• As layers of sediment build up over time,
  ________________________________
• _______ and become buried.
• 4. If conditions are right, the ________ may be
  kept intact and free from decay.
• The sediment gradually _____________
• _______

dead organisms may also sink to the bottom
remains
compresses into rock.
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Figure 17-2 Formation of a Fossil
Section 17-1
Water carries small rock particles to lakes and
seas.
Dead organisms are buried by layers of sediment,
which forms new rock.
The preserved remains may later be discovered and
studied.
Go to Section
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III. Interpreting Fossil Evidence

• A. Paleontologists determine the ________
  _______ using two techniques
• 1. Relative Dating
• a. The age of the fossil is determined by
  ______________________ with that of fossils in
  other layers of rock.
• b. Rock layers __________________ are
  generally ________ than those below it.

age of fossils
comparing its placement
nearer to the surface
younger
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Relative Dating
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• c. Does not determine the ___________ of the
  rocks or the fossils.
• d. Index fossils are used to ____________
  ___________________. These fossils must be
  easily recognized and must have existed for a
  short period of time.

actual age
compare the relative
age of fossils
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• 2. Radioactive Dating
• a. Based on the ___________________
  ___________________.
• b. Radioactive elements decay, ________
  ______, at a steady rate which is measured
  in a unit called half-life.
• c. Half-life the length of time required
  for __________________________ in a sample to
  decay.

radioactive decay of elements in the rocks
or break down
half of the radioactive atoms
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• d. Different radioactive elements have
  different half-lives and therefore provide
  ______________ that tick at ______________.
• Example
• Carbon-14 half-life of about ______
  ________
• Potassium-40 half-life of about ______
  ___________

natural clocks
different rates
5,730 years
1.26 billion years
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• e. Carbon-14 is _________ by living things
  while ______________. After an organism dies,
  the __________ in its body begins to decay to
  form _________ ___, which escapes into the air.
• Carbon-14 has a relatively ____________,
• it is useful only for dating fossils younger
  than about ____________.

taken up
they are alive
Carbon-14
nitrogen- 14
short half-life
60,000 years
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Carbon-14
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Radioactive Decay
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• B. Most fossils are __________.
  Paleontologists must reconstruct an extinct
  species from a few fossil bits--- remains of
  bone, a shell, leaves, or pollen.

not intact
http//www.colorado.edu/physics/2000/isotopes/radi
oactive_decay3.html
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Compare/Contrast Table
Section 17-1
Comparing Relative and Absolute Dating of Fossils
Relative Dating
Absolute Dating
Can determine Is performed by Drawbacks
Age of fossil with respect to another rock or
fossil (that is, older or younger)
Age of a fossil in years
Comparing depth of a fossils source stratum to
the position of a reference fossil or rock
Determining the relative amounts of a radioactive
isotope and non-radioactive isotope in a specimen
Imprecision and limitations of age data
Difficulty of radio-assay laboratory methods
Go to Section
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IV. Geologic Time Scale

• A. Scientists first developed the _________
  _____________ by studying rock layers and index
  fossils worldwide. As geologists studied the
  fossil record, they found _______ ________ in the
  fossil animals and plants
• _________________________. These times were
  used to mark the segments.

geologic time scale
major changes
at specific layers in the rock
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• 1. Eras There are __ eras between the
  ___________________________.
• a. ______________
• b. ______________ (Age of Dinosaurs)
• c. ______________ (Age of Mammals)
• 2. Periods Eras are subdivided into ______.

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Precambrian and the present
Paleozoic Era
Mesozoic Era
Cenozoic Era
periods
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Continental Drift
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Plate Boundaries
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San Andreas Fault
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17-2 Earths Early History and 17-3 Evolution
of Multicellular Life

• 4.6 bya.... ___________________
• many sources of energy volcanic activity,
  lightening, meteorites
• ______________ in atmosphere water vapor
  (H20), nitrogen (N2), and carbon dioxide
  (CO2), with only small amounts of hydrogen (H2)
  and carbon monoxide. The primitive
  atmosphere had little, if any, free _______.

no life forms present
poisonous gases
oxygen
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• intense UV (ultraviolet radiation) from sun
• In the presence of so much available energy,
  the primitive gases may have reacted with one
  another and produced small organic compounds,
  such as nucleotides and amino acids.

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• 3.5 bya geological disturbances have calmed
• ____________________________
• _____________ (much like the bacteria of
  today and well adapted)

bacteria evolve and inhabit most environments
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• 2.2 bya.... ____________________ and form
  mats in shallow seas. ________ ___________
  to produce oxygen (02) via ______________

cyanobacteria evolve
First organisms
photosynthesis
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• 1 bya.... algae and other water-borne
  photosynthetic organisms abound in the seas
• __________________ in the seas with
  many ______________________ like sponges,
  jellyfish and worms.

animal life abounds
multicellular organisms
Green Algae
Red Algae
Brown Algae
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A SPECIAL NOTE ON THE EVOLUTION OF OUR ATMOSPHERE
Oxygen saturation

• __________________ begins in the seas
• ____________________________ (electrical storms
  split atmospheric water molecules releasing a
  single oxygen)
• _______________________________ - (here single
  oxygen and regular oxygen unite to form O3 or
  ozone)
• ___________________ stratosphere - ________ _____
  most of the ________________. Life on land can
  now thrive under this protective ______ which
  begins 12-15 miles above the earths surface.

Oxygen moves into atmosphere
Oxygen reaches upper atmosphere
Ozone layer forms in
filtering out
harmful UV rays
shield
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• Paleozoic Era
• 550 mya.... ____________________ - the Cambrian
  Period records _____________ _______ of life in
  evolutions history. Nearly all of the animal
  groups known today as well as a strange
  collection of animals that cannot be assigned to
  any living group of today appeared in a period of
  about 10 million years. This evidence is not
  based upon fossils.

the Cambrian Explosion
an unmatched burst
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• 550 mya.... the Cambrian Explosion
• Scientists are ________________________
  ________________ of evolution found in the genes
  drawn from the living species of 16 animal
  groups. This has allowed scientists to estimate
  when all animals last shared a common ancestor
  with other forms of life. Although
  controversial, this evidence without the fossil
  backup is widely accepted by many scientists in
  the field today. If this finding holds up, the
  animal kingdom had __________________
  ___________to develop than the fossils reveal.

basing this new finding upon molecular
evidence
hundreds of millions of years longer
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410 mya..... the ______________
age of the fishes
Cartilaginous Fishes Sharks, Skates and Rays
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Bony Fishes
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• 360 mya...... ________________________ climb
  onto the land.

first land-based amphibians
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Amphibian Frog
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• 300 mya...... ______________________--the earth
  is now a large vegetated landmass with open
  plains, swamps and primitive trees. ____________
  flourished in a tropical climate. Invertebrates
  flourished in the ocean. From these forests and
  swamps, of the so called _____________ period,
  came the organic materials that ultimately formed
  our___________________.

primitive reptiles appear
Large insects
Carboniferous
fossil fuels of today
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Coal Forest Carboniferous Period (300 mya)
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• 240 mya... _______________________
  __________________________________ over a 100,000
  year period. This was possibly due to a meteor
  impact. This occurred at the end of
  the_____________.

a period of mass extinctions where perhaps
95 of all life perished
Paleozoic Era
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Mesozoic Era Began 245 myaLasted 180 million
years
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Reptiles Lay eggs on land
Bull Snake
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• 205 mya..... beginning of the domination of
  ___________ for 120 mya
• 138 mya..... ____________________ occur on land
  and the beginnings of tropical rain forests in
  some areas. The flowering plants spread and
  ultimately dominated the landscape through a
  period of 65 million years.

dinosaurs
first flowering plants
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• 65 mya.....
• Meteorite activity is one explanation
  for this extinction. This occurred at the end of
  the_______________.

an era of mass extinction that ended the
dinosaurs as well as 75 of all plant and animal
life.
Mesozoic Era
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Cenozoic Era Mammals spread out and began to
dominate the landscape.
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Mammal Chimpanzee
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• 100,000-200,00 years ago.......
• __________________ Homo sapiens date to about
  this time. Homo sapiens means _________
  __________ and modern humans are classified in
  this species.

the earliest fossils of
intelligent human
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17-4 overview
Species
that are
in
under
under
form
in
in
can undergo
can undergo
can undergo
can undergo
can undergo
Go to Section
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Study guide 17-1

• 1. Paleontologists
• 2. It is information about past life that is
  based on fossils.
• 3. It provides evidence about the history of life
  on Earth and how different groups of organisms,
  including species, have changed over time.
• 4. Extinct
• 5. False
• 6. B, D
• 7. Sediments settle to the bottom of lakes and
  seas ad bury dead organisms. The weight of upper
  layers of sediment compresses lower layers into
  rock and turns the dead organisms into fossils.
• 8. a) Relative dating b) Radioactive dating
• 9. A, B, D
• 10. False
• 11. True
• 12. Half-life
• 13. Radioactive dating
• 14. They measure the amount of remaining
  radioactive isotopes it contains. The smaller
  the amount, the older the sample.
• 15. False
• 16. Cenozoic, Mesozoic, Precambrian time,
  Tertiary, Jurassic, Carboniferous, Silurian,
  Cambrian
• 17. C
• 18. A, B
• 19. Eras and periods

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Study guide 17-2

• 1. a) Hydrogen Cyanide b) Carbon Dioxide c)
  Carbon Monoxide d) Nitrogen e) Hydrogen Sulfide
  f) Water
• 2. False
• 3. Spark simulating lightning storms
• 4. A, B
• 5. They are tiny bubbles, formed of large organic
  molecules, that have some characteristics of
  living cells.
• 6. False
• 7. Experiments show that small sequences of RNA
  could have formed and replicated on their own in
  the conditions present on early Earth.
• 8. DNA is a more stable information-storing
  molecule than RNA.
• 9. Microfossils
• 10. A
• 11. They produced oxygen, which first removed
  iron from the oceans and then accumulated in the
  atmosphere.
• 12. True
• 13. True
• 14. The first step was the evolution of internal
  cell membranes.
• 15. It proposes that eukaryotic cells arose from
  living communities formed by several organisms.
• 16. A,C,D
• 17. Sexual reproduction shuffles and reshuffles
  genes in each generation. This increase in
  genetic variation greatly increases the chances
  of evolutionary change due to natural selection.
• 18. False

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Study Guide 17-3

• True
• A,B,C
• The animals were al soft-bodied
• Cambrian
• False
• A,B,D
• B
• C
• A
• Devonian
• Vast swampy forests of giant ferns and other
  plants that grew during that time formed thick
  deposits of sediment that changed into coal over
  million of years.
• Mass extinction
• False
• Triassic, Jurassic, Cretaceous
• Reptiles
• Triassic
• True
• True
• Reptiles

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Study guide17-4

• Macroevolution
• a.)extinction b.)Adaptive radiation c.)Convergent
  evolution d.)Coevolution e.)Punctuated
  equilibrium f.)changes in developmental genes
• Possible causes include a huge asteroid striking
  Earth, many large volcanoes erupting, continents
  changing position, and sea levels changing.
• The disappearance of so many species left
  habitats open. Often, the result was burst of
  evolution that produced many new species.
• Adaptive evolution
• The disappearance of the dinosaurs led to the
  adaptive radiation of mammals.
• Convergent evolution
• B
• Coevolution
• Plats have evolved poisons prevent insects from
  feeding on them. Insects, in turn, have evolved
  ways of inactivating or eliminating the poisons.
• gradualism
• it may occur when a small population becomes
  isolated or a small group migrates to a new
  environment. It may also occur following a mass
  extinction.
• Punctuated equilibrium
• True
• Homologous hox genes establish body plans in
  animals that have not shared a common ancestor in
  hundreds of millions of years. In addition, major
  evolutionary changes may be based on hox genes.
• True

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Study guide Vocabulary review

• C
• D
• A
• C
• B
• In coevolution, two species evolve in response to
  changes in each other over time.
• Convergent evolution refers to the process by
  which unrelated organisms come to resemble one
  another as the evolve similar adaptations to
  similar environments.
• Mass extinction is the occurrence of many
  extinctions around the same time.
• Punctuated equilibrium is a pattern of
  macroevolution in which long, stable periods are
  interrupted by brief periods of rapid change.
• In adaptive radiation, a single species, or a
  small group of species, evolves into diverse
  forms that live in different ways.