Transcript c. sedimentary rock.

UNIT V
Chapter 17
The History
Of Life
III. The History of Life
A. The Fossil Record
1. Fossils and Ancient Life- fossils provide
evidence about the history of life on Earth and
how different groups have changed.
a. Paleontologist- scientist who study fossils
b. 99% of all species that ever lived are extinct
2. Interpreting Fossil Evidence
a. Most fossils form in sedimentary rock
3. Relative Dating- age of fossil determined by
comparing its placement with that of fossils in
other layers of rock.
youngest
oldest
4. Radioactive dating- use radioactive decay to
assign absolute ages to rocks. Age calculated by
calculating amount of radioactive decay it contains
B. Geologic Time Scaleevolutionary time based on
boundaries in fossil record
marked by mass extinctions
and explosive radiations of
new life forms
C. Earth’s Early History
1. Formation of Earth- formed about 4.6 billion
a. Early atmosphereyears ago
contained hydrogen
cyanide, carbon dioxide,
carbon monoxide,
nitrogen, hydrogen
sulfide, and water. No
oxygen!
b. Earth cooled enough
to allow first solid rocks
c. 3.8 billion years agocooled enough for water
to condense (formation of
first sedimentary rocks)
2. First organic molecules
a. Oparin-Haldane hypothesis- said
conditions on primitive Earth synthesized
organic compounds from inorganic compounds
b. Miller and Urey- conducted experiment to
determine if conditions would produce organic
compounds.
Scientists now know that
Miller and Urey’s original
simulations of Earth’s early
atmosphere were not acurate.
However, similar experiments
based on more current
knowledge of Earth’s early
atmosphere have also
produced organic compounds
D. How Did Life Begin
1. Formation of microspheres- under certain
conditions large organic molecules form tiny
bubbles called proteinoid microspheres. Have
some characteristics of living things. (storing and
releasing energy)
Microspheres are not cells, but
they have some characteristics
of living systems. Like cells,
they have selectively
permeable membranes through
which water molecules can
pass.
2. Evolution of RNA and DNA- puzzle not solved
yet. Think that RNA existed first and could grow and
duplicate themselves. May then have DNA-directed
protein synthesis that now exists.
3. Free oxygen- from original anaerobic prokaryotes
(bacteria) eventually photosynthetic bacteria evolved
and began to produce oxygen (about 2.2 billion
years ago)
a. Rise in oxygen led to extinctions of some
organisms
b. Also led to rise in new life forms using oxygen
in metabolic pathways
4. Origin of Eukaryotic cells (about 2 billion years
ago)
a. Endosymbiotic theory- proposes eukaryotic
cells arose from living comunities formed by
several organisms
b. Some cell organelles have features of free-living
bacteria
1). Mitochondria and chloroplasts contain DNA
and ribosomes similar to bacteria’s DNA and
ribosomes
2). Mitochondria and chloroplasts reproduce by
binary fission when cells containing them divide by
mitosis
5. Sexual reproduction and multicellularity
a. Sexual reproductionarose soon after eukaryotic
cells- led to increase in
genetic variation and
evolutionary change in
species due to natural
selection
b. Multicellular cells- few
hundred million years after
sexual reproduction
Ancient jellyfish, an early
multicellular animal from
Precambrian time
D. Patterns of Evolution- six major patterns
account for large scale evolutionary changes
(macroevolution)
1. Mass Extinctions- led to disappearance of
huge number of species. Often led to burst of
evolution and new species
2. Adaptive Radiation- single species or small
group of species has evolved into several different
forms that live in different ways. Like Darwin’s
finches.
3. Convergent Evolution- natural selection molds
similar body structures in unrelated organisms.
Convergent Evolution and analogous structures. The ocotillo of
Southwestern North America (left) looks remarkably similar to the alluidia
(right) found in Madagascar. The plants are not closely related and owe
their resemblance to analogous adaptations that evolved independently
in response to similar environmental pressures
4. Coevolution- evolutionary change in one
organism may also be followed by corresponding
change in another organism.
Example: orchid has unusually
long spur containing supply of
nectar. The hawk moth has
equally long feeding tube enabling
it to feed on nectar
5. Punctuated Equilibrium- long stable
periods interrupted by brief periods of
more rapid change. Can occur for
several reasons- genetic drift, conditions
following mass extinctions
6. Developmental genes and body plans- the
changes in timing of certain genes during embryonic
development can contribute to genetic variation
Fossil evidence shows that
some ancient insects had
no wings, but others had
wing-like structures on
many body segments. In
modern insects (bottom),
genes may turn off wing
Hox genes in all except
development
one or two body segments.
Chapter 17
The History
Of Life
What proportion of all species that ever lived has
become extinct?
a.
less than 1 percent
b.
approximate one-half
c.
more than 99 percent
d.
It is impossible to estimate.
What proportion of all species that ever lived has
become extinct?
a.
less than 1 percent
b.
approximate one-half
c.
more than 99 percent
d.
It is impossible to estimate.
Most fossils form in
a.
peat bogs.
b.
tar pits.
c.
sedimentary rock.
d.
the sap of ancient trees.
Most fossils form in
a.
peat bogs.
b.
tar pits.
c.
sedimentary rock.
d.
the sap of ancient trees.
The length of time required for half of the
radioactive atoms in a sample to decay is its
a.
half-life.
b.
relative date.
c.
radioactive date.
d.
none of the above
The length of time required for half of the
radioactive atoms in a sample to decay is its
a.
half-life.
b.
relative date.
c.
radioactive date.
d.
none of the above
How would you date a sample of rock that you
suspect as being one of the earliest on Earth?
a.
Use a radioactive isotope with a short half-life.
b.
Use a radioactive isotope with a long half-life.
c.
Use an index fossil.
d.
It is impossible to date very early rocks.
How would you date a sample of rock that you
suspect as being one of the earliest on Earth?
a.
Use a radioactive isotope with a short half-life.
b.
Use a radioactive isotope with a long halflife.
c.
Use an index fossil.
d.
It is impossible to date very early rocks.
The levels of division of the geologic time scale,
from smallest to largest are
a.
eras, periods, and epochs.
b.
epochs, periods, and eras.
c.
periods, eras, and epochs.
d.
periods, epochs, and eras.
The levels of division of the geologic time scale,
from smallest to largest are
a.
eras, periods, and epochs.
b.
epochs, periods, and eras.
c.
periods, eras, and epochs.
d.
periods, epochs, and eras.
The Mesozoic is often called the Age of
a.
Invertebrates.
b.
Vertebrates.
c.
Dinosaurs.
d.
Mammals.
The Mesozoic is often called the Age of
a.
Invertebrates.
b.
Vertebrates.
c.
Dinosaurs.
d.
Mammals.
Earth's most recent era is the
a.
Paleozoic.
b.
Mesozoic.
c.
Cenozoic.
d.
Precambrian.
Earth's most recent era is the
a.
Paleozoic.
b.
Mesozoic.
c.
Cenozoic.
d.
Precambrian.
Why did oceans not exist on Earth nearly 4 billion
years ago?
a.
No water was present.
b.
Water remained a gas because Earth was
very hot.
c.
Water existed as ice because Earth was very
cold.
d.
none of the above
Why did oceans not exist on Earth nearly 4 billion
years ago?
a.
No water was present.
b.
Water remained a gas because Earth was
very hot.
c.
Water existed as ice because Earth was very
cold.
d.
none of the above
Miller and Urey's experiments attempted to simulate
the conditions
a.
of Earth's early seas.
b.
of Earth's early atmosphere.
c.
of Earth before liquid water existed.
d.
deep inside Earth.
Miller and Urey's experiments attempted to simulate
the conditions
a.
of Earth's early seas.
b.
of Earth's early atmosphere.
c.
of Earth before liquid water existed.
d.
deep inside Earth.
A necessary condition for the evolution of life on
Earth was
a.
the existence of DNA.
b.
free oxygen.
c.
the formation of the ozone layer.
d.
liquid water.
A necessary condition for the evolution of life on
Earth was
a.
the existence of DNA.
b.
free oxygen.
c.
the formation of the ozone layer.
d.
liquid water.
What do proteinoid microspheres have in common
with cells?
a.
They can store and release energy.
b.
They contain DNA.
c.
They contain RNA.
d.
They are communities of organisms.
What do proteinoid microspheres have in common
with cells?
a.
They can store and release energy.
b.
They contain DNA.
c.
They contain RNA.
d.
They are communities of organisms.
The endosymbiont theory proposes that eukaryotic
cells arose from
a.
single prokaryotic cells.
b.
multicellular prokaryotes.
c.
communities of prokaryotes inside a larger
cell.
d.
communities of eukaryotes inside a larger
cell.
The endosymbiont theory proposes that eukaryotic
cells arose from
a.
single prokaryotic cells.
b.
multicellular prokaryotes.
c.
communities of prokaryotes inside a larger
cell.
d.
communities of eukaryotes inside a larger
cell.
What was the response of various groups of early
organisms when oxygen levels rose in the
atmosphere?
a.
extinction
b.
a move into airless habitats
c.
the evolution of metabolic pathways that used
oxygen for respiration
d.
all of the above
What was the response of various groups of early
organisms when oxygen levels rose in the
atmosphere?
a.
extinction
b.
a move into airless habitats
c.
the evolution of metabolic pathways that used
oxygen for respiration
d.
all of the above
The first organisms were
a.
prokaryotes.
b.
eukaryotes.
c.
proteinoid microspheres.
d.
microfossils
The first organisms were
a.
prokaryotes.
b.
eukaryotes.
c.
proteinoid microspheres.
d.
microfossils
A very large mass extinction occurred at the end of
the
a.
Precambrian.
b.
Cambrian Period.
c.
Paleozoic Era
d.
Quaternary Period.
A very large mass extinction occurred at the end of
the
a.
Precambrian.
b.
Cambrian Period.
c.
Paleozoic Era
d.
Quaternary Period.
The process by which two species evolve in
response to each other, for example, a flower
having a structure compatible with the body
structure of its pollinator, is an example of
a.
convergent evolution.
b.
adaptive radiation.
c.
coevolution.
d.
punctuated equilibrium.
The process by which two species evolve in
response to each other, for example, a flower
having a structure compatible with the body
structure of its pollinator, is an example of
a.
convergent evolution.
b.
adaptive radiation.
c.
coevolution.
d.
punctuated equilibrium.
A mass extinction would encourage the rapid
evolution of surviving species
a.
by changing developmental genes.
b.
by opening ecological niches.
c.
because it killed all organisms that had
coevolved.
d.
because it spared all organisms that had
evolved convergently.
A mass extinction would encourage the rapid
evolution of surviving species
a.
by changing developmental genes.
b.
by opening ecological niches.
c.
because it killed all organisms that had
coevolved.
d.
because it spared all organisms that had
evolved convergently.
A single species that has evolved into several
different forms that live in different ways has
undergone
a.
adaptive radiation.
b.
coevolution.
c.
punctuated equilibrium.
d.
mass extinction.
A single species that has evolved into several
different forms that live in different ways has
undergone
a.
adaptive radiation.
b.
coevolution.
c.
punctuated equilibrium.
d.
mass extinction.
Two patterns of macroevolution that involve very
rapid response to environmental pressures are
a.
convergent evolution and changes in
developmental genes.
b.
coevolution and convergent evolution.
c.
adaptive radiation and changes in
developmental genes.
d.
punctuated equilibrium and mass extinction.
Two patterns of macroevolution that involve very
rapid response to environmental pressures are
a.
convergent evolution and changes in
developmental genes.
b.
coevolution and convergent evolution.
c.
adaptive radiation and changes in
developmental genes.
d.
punctuated equilibrium and mass
extinction.