8-2 Benchmark Study Guide
8-2.1 Explain how the biological adaptations of populations enhance their survival in a particular environment.
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Populations in a particular environment that are better adapted to living conditions there, and
therefore are able to meet their survival needs, are more likely to survive and reproduce offspring
with those traits.
The environment influences which organisms can live in an area. You will not see a large evergreen
tree growing in a desert.
Pollution limits where a species can survive. Fire, height of mountains, volcanic eruptions, and
flooding of rivers can influence the animals and plants in an area.
Predators, competition for food, and territory, overharvesting, humans, cutting down trees limit
the number of animals that live in an area.
Variations: there are variations among species of similar populations. For example, humans have
different hair, eye or skin color. Sometimes these changes provide an advantage to an organism’s
survival.
Adaptation: a trait or behavior that helps an organism to survive and reproduce.
Natural Selection: the process that explains the survival of a species and shows how species can change
(Survival of the fittest!): Changes happen from generation to generations that results in adaptations
to the environment.
Variation: Different Eye Colors
Adaptations: sharp teeth/webbed feet
Natural Selection: Survival of
the Fittest
EVOLUTION
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What is evolution? Evolution is a gradual process in which something changes into a different and
usually more complex or better form.
How does evolution happen? they proposed that organisms that are better adapted to an environment
survive and reproduce at a greater rate than organisms that are not which is called natural selection
because the adapted organisms are selected naturally to survive and increase in number. Natural
selection can produce new organisms or new species.
8-2.2
Summarize how scientists study Earth’s past environment and diverse life-forms by examining different types of
fossils (including molds, casts, petrified fossils, preserved and carbonized remains of plants and animals, and trace
fossils).
 forms when sediments bury an
organism and the sediments
change into rock; the organism
decays leaving a cavity in the
shape of the organism.
forms when a mold is filled with
sand or mud that hardens into
the shape of the organism.
 (permineralized fossil) –
forms when minerals soak
into the buried remains,
replacing the remains, and
changing them into rock.
 forms when entire organisms
or parts of organisms are
prevented from decaying by
being trapped in rock, ice,
tar, or amber.
 forms when organisms or
parts, like leaves, stems,
flowers, fish, are pressed
between layers of soft mud
or clay that hardens
squeezing almost all the
decaying organism away
leaving the carbon imprint
in the rock.
forms when the mud or sand
hardens to stone where a
footprint, trail, or burrow of an
organism was left behind
FOSSIL FORMATION
1.
2.
3.
4.
5.
Animal must die near water
Compaction and Cementation
Petrification (turns into rock)
Uplift (plates are moving)
Erosion reveals the fossils
8-2.3 Explain how Earth’s history has been influenced by catastrophes (including the impact of an
asteroid or comet, climatic changes, and volcanic activity) that have affected the conditions on
Earth and the diversity of its life-forms.
Caused the mass extinction during the Mesozoic Era (The age of
Dinosaurs) This impact caused dust and smoke to rise into the
atmosphere and cause climatic changes, as well as the dying of many
forms of plant life and animals that depended on those plants for food.
The result of such an impact would be an enormous explosion that
would throw dust clouds into the sky, darkening the planet. Massive
forest fires, triggered by the hit, would add smoke to the sky. This
would cool the planet causing the climatic changes observed.
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affected all Eras, if animals could not adapt to the
climate change they would die
Life on land developed and flourished in the tropical climates and
warm shallow seas during the Paleozoic Era. Throughout this era
as different land environments formed and sea levels changed, new
life forms developed. Other life forms that could not adapt or find
suitable conditions, especially many marine species, disappeared.
During the Mesozoic era, many climate changes occurred due to
plate tectonics and the movement of landmasses. Plants and
animals that survived through this time had structures and systems
that allowed for greater adaptations, such as seed coverings for
plant seeds and protective body coverings or constant internal
temperature for animals.
During the present Cenozoic era, climate conditions continue to
change. Major ice ages caused the climate to become much cooler
as ice sheets and glaciers covered many areas of Earth. Many
mountain ranges formed causing climate differences due to
elevation and due to location near those ranges.
From the earliest days while Earth was forming to present day, volcanic
activity has been part of the nature of this changing planet. During the
Precambrian time volcanic activity was one of the most natural events,
but lava flows, ash clouds in the atmosphere, and heat made conditions
for life forms extremely difficult. Those simple life forms often did not
survive these conditions. Helped formed the crust of the Earth: igneous
rocks and it destroyed plants and animals
8-2.4 Recognize the relationship among the units – era, period, and epoch – into which the geologic time
scale is divided.
Geologic time scale divides Earth’s long history into units of time:
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Eons are divided into eras
Eras are divided into periods
Periods can be further divided into epochs:
E + P = EP (Eras + Periods = Epochs)
THE DIVISIONS FROM LARGE TO SMALL: EONS, ERAS, PERIODS, AND EPOCHS
THE DIVISIONS FROM SMALL TO LARGE: EPOCHS, PERIODS, ERAS, AND EPOCH
Major information found on the geologic time scale includes:
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Geologists divide the time between Precambrian and the present into three long units called eras
(Paleozoic, Mesozoic, Cenozoic). The names of the eras are important, as is the order from oldest era to
most recent.
Cambrian being the first period is important.
With a more complete fossil record available, the periods of the Cenozoic era are subdivided further into
epochs.
Present day Earth is in the Cenozoic era and the Quaternary period in the Holocene epoch.
Geologic time has not ended.
8-2.5 Illustrate the vast diversity of life that has been present on Earth over time by using the geologic
time scale.
Precambrian Time
longest time in Earth’s history (88%),
invertebrates, trace fossils, cyanobacteria
(blue green bacteria), soft body organisms,
stromatolites, covered mostly by oceans
Paleozoic Era (ancient life) Age
of the Trilobites
-most things formed during this
era
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Pangaea was forming, vertebrates,
brachiopods, mountain ranges started to
form, amphibians(reptiles), fish, arachnids
(insects), forest began to grow,
Early land plants included simple mosses,
ferns, and then cone-bearing plants.
By the end of the era, seed plants were
common.
The mass extinction that ended the era
caused most marine invertebrates as well
as amphibians to disappear.
Mesozoic Era (middle life)
Age of the Dinosaurs
Pangaea forms and breaks apart, reptiles
became abundant, small mammals and birds
appeared, Gymnosperms, and flowing plants,
asteroid or comet caused an extinction during
this era
The mass extinction that ended the era caused
the dinosaurs to become extinct.
Cenozoic Era (recent life)
Age of the Mammals
Ice age, continents are in present locations,
mammals were dominant, humans, mountain
ranges forms, grasslands expanded, whales,
dolphins, horses, and etc…..
The diversity of life forms increased.
Flowering plants became most common
8-2.6
Infer the relative age of rocks and fossils from index fossils and
the ordering of rock layers.
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Relative age (guess age, ex: younger) vs. Absolute age (actual age, ex: 14)
Law of Superposition: youngest rock layers on top and oldest rock layers are on the bottom
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Cross-Cutting sections: Faults and Intrusion: if it goes through the rock layers, then it is the youngest
Index fossils: lives for only a short period of time and can tell the age of a rock layer …. Ex: trilobites
Unconformity : gap in the geologic record: shows where rock layers have been lost due to erosion
8-2.7 Summarize the factors, both natural and man-made, that can contribute to the extinction of a
species.
TYPE OF FACTOR
Factors That Can Contribute to the
Extinction of Species
Natural Factors
Organisms that could not survive changes due to
volcanic eruptions and global warming, global
cooling during ice ages, changes in oxygen levels in
seawater, or a massive impact from an asteroid or
comet became extinct.
ICE AGE
Man-Made Factors
cutting of the rainforest regions, removing natural
habitats, over-harvesting (over hunting or killing
animals), and pollution.
OVER HARVESTING FISH
Directions: Select the best answer for each question.
1. (8-2.1) Food has become limited in the ocean.
The animal who has the best adaptation to
survive with less food would be the _________.
a
.
b
.
c
.
.
2.
(8-2.1) The Lion lives in the
Savannah of Africa, a dry grassland. The Lion’s
trait that would be the most beneficial in
helping it survive in this hot environment is its
__________.
a. Large Size
b. Light Color
c. Long Claws
d. Sharp Teeth
3. (8-2.1) The brown fur of the arctic hare turns
white in winter. How does this color change
most likely help the arctic hare?
a. It helps the animal hide from predators.
b. It helps the animal save water.
c. It helps keep the animal cool.
d. It helps protect the animal from
disease.
4. (8-2.2/3.6) Fossils of warm-weather plants were
found on an island in the Arctic Ocean. What
can best be concluded from this discovery?
a. Spores of plants drifted by air currents
to the island.
b. Ocean currents carried the plants to the
island.
c. The island drifted from a tropical region
to its present location.
d. Seeds of plants have been carried to the
island by migratory birds.
d
.
5. (8-2.6) Index fossils help
scientists estimate the age of a rock because
index fossil species only existed for a relatively
short time. What happened to the species that
are now used as index fossils?
a.
b.
c.
d.
They became extinct.
They changed their diets.
They hid in marine sediments.
They migrated to new environments.
6. (8-2.2) Which of the following would not be
considered a preserved fossil?
a. A dinosaur tooth.
b. A fly caught in amber.
c. A frozen mammoth.
d. A plant fossil in a tar pit.
7. (8-2.6) Which rock layer is probably the oldest?
a.
b.
c.
d.
1
3
4
6
8. (8-2.3) Which theory best describes how an
asteroid striking Earth may have caused the
extinction of dinosaurs?
a. Heat from the asteroid caused massive
fires that reduced the food supply.
b. Dense clouds formed following the
collision, causing a global drop in
temperature.
c. Land masses were altered by the
collision, reducing the space where
dinosaurs could roam for food.
d. Glaciers melted rapidly from heat
produced by the asteroid, causing
floods that destroyed dinosaurs’
habitats.
9. (8-2.4) In geologic time, epochs are combined
to make _____________.
a.
b.
c.
d.
Eons
Eras
Periods
Millennia
10. (8-2.4) The longest segment of geologic time is
the _____________.
a.
b.
c.
d.
Cenozoic
Mesozoic
Paleozoic
Precambrian
11. (8-2.6) The White Cliffs of Dover are made of a
white sedimentary stone called chalk, which
was formed when shells and skeletons of small
marine organisms were deposited in a thick
layer. An examination of the Cliffs of Dover
from top to bottom would show a change from
a. igneous rock to sedimentary rock.
b. marine organisms to land organisms.
c. simple fossils to complex fossils.
d. younger fossils to older fossils.
12. (8-2.5) The dominant life-form during the
Mesozoic Era was ____________.
a.
b.
c.
d.
Insects
Amphibians
Humans
Reptiles
13. (8-2.7) Clams, oysters, and mussels eat plankton
filtered from water. How would clams, oysters,
and mussels most likely be affected if the
amount of plankton in a large body of water
was significantly reduced?
a. They would increase in number.
b. They would find a new food source.
c. They would become prey to other
animals.
d. They would compete for a limited food
source.
14. (8-2.7) A park is home to a large number of
robins, squirrels and rabbits. The robins and
squirrels live in the park’s trees. The robins feed
on earthworms and insects that live on the
ground. The squirrels eat the acorns produced
by the park’s oak trees. The rabbits hide in the
bushes and feed on the grass. Which factor
would directly limit the number of rabbits that
could live in this park?
a.
b.
c.
d.
number of acorns
number of bushes
number of robins
number of squirrels
15. (8-1.6) The water level in a graduated cylinder
rises from 10 cm3 to 35 cm3 when a solid lead
ball is added. What is the approximate volume
of the lead ball?
a.
b.
c.
d.
3.5 cm3
25 cm3
35 cm3
45 cm3
16. (8-2.4) The shortest time division was
___________
a. Cenozoic
b. Mesozoic
c. Paleozoic
d. Precambrian
17. (8-2.5) The Himalayas formed during the
____________
a. Cretaceous Period
b. Eocene Epoch
c. Protezonic Eon
d. Ordovician Period
18. The modern day is part of the ______________
a.
b.
c.
d.
Cenozoic Era and Neogene
Pleistocene Epoch and Phanerozoic Eon
Quarternary Period and Cenozoic Era
Tertiary Period and Pliocene Epoch
19. (8-1.3) Earthquake waves are detected by an
instrument
called a seismograph, and the data are
recorded visually on a
seismogram. To determine the location
of an earthquake,
scientists must determine the amount
of time between the
first arrival of the P wave and the first
arrival of the S wave at
the location of the seismograph.
According to the data in the
seismogram shown above, how much
time elapsed between
the arrival of the P wave and the arrival
of the S wave?
a.
b.
c.
d.
11 seconds
25 seconds
37 seconds
90 seconds
20. (8-2.6) In order for a fossil to be used as an
index fossil, the organism must have been
found over a wide area of Earth and must have
____________.
a. Lived on land
b. Lived in shallow water
c. Existed for a geologically short period of
time
d. Been preserved in volcanic ash
21. (8-2.2) Which is most likely to become a fossil?
a. A skeleton in a large lake
b. A jellyfish in the ocean
c. An earthworm in a damp forest
d. A skeleton in a riverbed that is drying
up
22. (8-2.2) If a fossil dissolves away, it can leave
behind a cavity in the rock called a _________.
a. Mold
b. Cast
c. Carbonized
d. Sediment
23. (8-2.4) Eras of the geologic time scale are
divided into _________.
a. Periods
b. Ages
c. Units
d. Epochs