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BIOLOGY 1
BIOLOGY
Chapter 12 Notes
I. To find out when the first organism form, scientists study the best evidence of early life
that we have, _____________________.
A. A __________________ is the preserved or mineralized remains or imprint of an
organism that lived long ago.
1. The oldest fossils are microscopic fossils of ______________________,
which are single celled organisms that lack internal membrane bound
organelles.
a. Prokaryotes are also known as ______________________.
B. Among the first of the bacteria to appear were _________________________,
which are photosynthetic bacteria.
1. Before these appeared, __________________ gas was rare on Earth; since
then, they carried out _________________________ and released oxygen
gas into Earth’s oceans.
2. After millions of years, the oxygen that was produced began to escape into
the ____________.
a. Today, oxygen gas makes up _____________ of the Earth’s
atmosphere.
C. Early in the history of life, there were two different groups of prokaryotes:
1. _______________________ are prokaryotes that contain a chemical in
their cell walls and have the same type of ________________ in their cell
membranes as eukaryotes.
a. These include many bacteria that causes ___________________ and
__________________.
2. ______________________________ are prokaryotes that are thought to be
closely related to the first bacteria to have existed.
BIOLOGY 2
a. __________________________ evidence indicates that the first
eukaryotic cells are more likely to have evolved from these than from
eubacteria.
II. The History of Life
A. _____________________________ is the science of identifying and classifying
organisms according to guidelines.
1. Classification of categories:
a. Domain:
b.
c.
d.
e.
f.
g.
h.
2. 5 Kingdoms
a.
b.
c.
d.
e.
B. About _______________ of all time on earth was during the
_______________________ time, which was about ________ million to _______
billion years ago.
1. 4 BYA (billion years ago)2. 3.1-3.5 BYA
3. 2.5 BYA
4. 2 BYA
5. 700 MYA
C. Paleozoic Era1. Cambrian Period
BIOLOGY 3
2. Ordovician3. Silurian4. Devonian5. Carboniferous6. PermianD. Mesozoic Era1. Triassic2. Jurassic3. CretaceousE. Cenozoic Era1. Paleogene2. NeogeneF. Fossils records indicated a sudden change at the end of the ___________________
period.
1. About 440 million years ago, a large percentage of the organisms on Earth
suddenly became ____________________.
a. A ___________________________________ is the death of all
members of many different species, usually caused by a large
ecological disaster.
2. There have been about 5 major mass extinctions:
a. At the end of the Ordovician period.
b. One about 360 million years ago at the end of the
____________________ period.
c. The most devastating of all happened about 245 million years ago at
the end of the ____________________________ period.
1. About __________ of all species of animals living at the
time became extinct.
d. At the end of the _________________ period there was a less
severe extinction.
e. The last and one of the most devastating extinctions happened at the
end of the _________________________ period.
BIOLOGY 4
1. About ___________ of all land species, including the
__________________________, became extinct.
G. Scientists believe that another mass extinction is occurring ____________.
1. Their reason for this belief is the Earth’s ecosystem, especially the
_________________________________________, are being destroyed by
human activity.
a. The world has already lost __________ of its tropical rain forests,
and at the rate they are being destroyed:
2. As many as _______________ species of plants (one quarter of the world’s
total), and _____________ of the world’s ______________ species of birds
and countless insects will all be lost.
III. The _________ provides both life-giving light and dangerous ultraviolet radiation.
A. Early in Earth’s history, life formed in the ___________.
1. Organisms could not leave the water because of the _________________
_________________________.
B. The primitive atmosphere was mostly made up of:
C. The modern atmosphere was made because ________________________began
adding oxygen to the atmosphere by ____________________________.
1. As oxygen began to reach the upper atmosphere, the sun’s rays caused
some of the molecules of oxygen, O2, to bond and form molecules of
_________, O3.
a. In the upper atmosphere, __________ blocks the UV radiation of
the sun.
b. Over millions of years, enough ozone had accumulated to make the
Earth’s land a _____________ place to live.
IV. The first organisms.
A. The first multicellular organisms to live on land are thought to have been
____________ and ______________ living together.
BIOLOGY 5
1. _____________________, which evolved from photosynthetic protists,
could carry out photosynthesis; however, they could not harvest needed
minerals from bare rock.
2. ____________________ could not make nutrients from sunlight, but could
absorb minerals from bare rock.
3. Plants and fungi evolved biological partnerships called
____________________________, which enabled them to live on the harsh
habitat of bare rock.
4. The fungi provide minerals to the plant, and the plant provides nutrients to
the fungi. This kind of partnership is called
__________________________.
a. This is a relationship in which ____________organisms benefit.
B. By _________________________ after their first union with fungi, plants had
covered the surface of the Earth, forming large forests.
1. These plants provided a __________ source for animals, enabling the
evolution of land dwelling animals.
2. The first animals to successfully invade land from the sea were
_____________________________, a kind of animal with a hard outer
skeleton and jointed limbs.
a. Examples:
3. A unique kind of terrestrial arthropod, the _________________, evolved
from the first land dwellers.
a. Insects have since become the ___________________ and
_______________ group of animals in Earth history.
b. The success of this insect is probably connected to their ability to
______________.
c. Flying allowed insects to efficiently search for _____________,
________________ and nesting sites.
d. Also led to the partnership between insects and
_____________________________________.
C. ________________________ are animals with a backbone.
BIOLOGY 6
1. The first vertebrates were ______________, jawless fish that evolved in the
oceans about 500 MYA.
2. Jaws fish first appeared about 430 MYA and the jaw enabled fish to
__________ and _____________ their food.
D. The first vertebrates to inhabit the _____________ did not come out of the sea
until 370 million years ago.
1. The first land vertebrates were early __________________________,
which are smooth-skinned organisms that include ______________,
_____________, and __________________________.
2. They were able to adapt to land because of the development of several
___________________ changes in their body.
a. Examples:
E. __________________- evolved from amphibians.
1. Reptiles include:
2. These animals evolved a __________________________, which protected
them from losing moisture to the atmosphere.
a. Also developed a watertight _______, for reptiles to lay their eggs
on dry land and they still be surrounded by a watertight shell.
b. Reptiles are better adapted for _________________________, so
they became the more abundant vertebrate on Earth until about 65
MYA.
F. Birds evolved from ________________ during the Jurassic period.
1. During the fifth mass extinction, _____________ species disappeared
forever.
a. Some scientists believe that smaller ____________,
_______________ and ____________ survived.
BIOLOGY 7
b. ________________ and _____________________ became the
dominant vertebrates on land.
G. _______________________________ is the movement of Earth’s land masses
over geologic time.
1. Continental drift resulted in the __________________ position of the
continents.
2. The movement of continents helps explain why there are a large number of
marsupial species in ___________________ and ______________________,
continents that were once connected.