Evidence of Common Ancestry and Diversity Chapter Problems
Fossils
Class Work
1. What is a fossil?
2. What is fossilization?
3. Why aren’t fossils more common?
Homework
4.
5.
6.
7.
How are fossils formed?
Where are marine fossils found on top of mountains?
Describe the process of excavating fossils.
What type of rocks are fossils found in?
Types of Fossils
Class Work
8. Complete the following chart on the five types of fossils
Type of Fossil
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Features or Characteristics
6th Grade PSI
Evidence of Common Ancestry
Homework
9. What happens to organisms that are not turned into fossils?
10. Can fossils be classified by more than one type? Give an example.
Fossilization Process
Class Work
11. Complete the following chart on the six fossilization processes
Fossilization Process
Features or Characteristics
Homework
12. How does is fossilization different from petrification?
13. What types of substances preserve an organism to create unaltered preservation?
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Geological Timeline
Class Work
14. What is the geological timeline?
15. What percentage of time does the Phanerozoic era cover?
16. What is the Cenozoic Era known as?
Homework
17. The Phanerozoic eon is split into what three eras?
18. What is the Mesozoic Era known as?
19. What super continent existed during the Mesozoic Era?
Dating Fossils
Class Work
20. How are sedimentary layers formed?
21. Explain the principle of Lateral Continuity.
22. What is the principle of Faunal Succession?
23. What is the fossil record and how does it help track the history of life on Earth?
24. How does carbon dating provide the age of a fossil?
Homework
25. What is the principle of Original Horizontality?
26. Explain the principle of superposition and how it helps with the dating of fossils.
27. Describe how the fossil index helps with relative dating.
Similarities and Differences
Class Work
28. What do anatomical similarities tell us about evolution?
29. Define homologies
30. Explain the theory of common ancestry.
31. How do cell functions support the theory of evolution?
Homework
32. What are analogous structures?
33. What support is there for the theory that all life on Earth shares a common
ancestor?
34. What are vestigial structures? Give an example.
35. What do similarities in DNA prove about evolution?
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Evidence of Common Ancestry
Evolution
Class Work
36. Define evolution
37. Does all life on Earth have a shared history? Explain.
38. Describe genetic migration.
39. What is natural selection?
40. How does the fossil record support evolution and a common ancestor?
41. What is embryological development and how does it support evolution and a
common ancestor?
Homework
42. What did Charles Darwin believe is responsible for the diversity of life on Earth?
43. What are mutations in DNA? Give an example
44. Define genetic drift
45. Define biogeography
46. What are some traits that human embryos share with other mammals?
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Evidence of Common Ancestry
Answer Key
Fossils
Class Work
1) Fossils are the preserved remains of prehistoric organisms.
2) Fossilization is the complex process of converting a plant or animal remains into a
fossil.
3) Fossils only form under certain conditions and are rather rare. Factors such as the rate
decomposition and predation effect the chances of remains turning into fossils.
Homework
4) Fossils are formed when dead organism’s bones are quickly covered with sediment.
Over time more sediment piles up on top of the bones. After millions of years the bones
become part of the rock through fossilization.
5) The marine fossils were deposited when the area was covered by an ocean. The
continental uplift of caused the formation of mountains. Weathering and erosion aids in
the discovery of the fossils.
6) Fossils must be carefully freed from the encasing rocks without damaging it. Hand
tools are used to free the surrounding rock.
7) Sedimentary rocks
Types of Fossils
Class Work
8) Complete the following chart on the five types of fossils
Type of Fossil
Features or Characteristics
Mold Fossils
Mold fossils form when the hard parts of
organic material are buried in sediment.
Over time the hard parts dissolve and
disappear completely leaving a negative
image of the fossil.
Cast Fossils
Cast fossils form as the result of a mold.
After an organism has create a mold,
minerals enter the cavity and fill in the
impression.
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True Form Fossils
True form fossils are the actual remains,
including the body of a soft tissue of an
organism. Organisms are preserved in
their original state when they are
trapped in amber or tar. Additionally, if
an organism dies in a very cold region it
can be frozen in ice which preserved the
entire organism.
Trace Fossils
Trace fossils provide clues to the
activities of ancient organisms.
Impressions left by an animals or plants
are buried under layers of sediment and
over time become solid rock. Trace
fossils include footprints, tooth marks on
bones, fossilized feces, nest or burrows.
Carbon Film Fossils
As organisms decompose thin layers of
carbon is left on the rock, creating
silhouette with fine details. This process
is sped up by effects of pressure and
heat.
Homework
9) The remains of plants and animals that aren't turned into fossils sometimes end up as
fossil fuels. Over time the organic remains are exposed to heat and pressure that turns
them into oil, natural gas or coal.
10) Fossils are often preserved by more than one form and can be classified as such.
Carbon film fossils created by plants can also leave a cast and mold. Additionally, cast
fossils such as trilobites are often mineralized.
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Fossilization Process
Class Work
11) Complete the following chart on the six fossilization processes
Fossilization Process
Features or Characteristics
Permineralization
As plant and animal remains are buried
under sediment, ground water slow
penetrates the pores. Over time the
water deposits their mineral content
replacing the organic tissues, resulting in
the formation of a petrified fossil.
Unaltered Preservation
Occurs when organisms are preserved in
a substance, such as amber, ice or tar,
preserves the organisms and prevents
the decay of tissue. A baby mammoth
trapped in ice for thousands of years is
preserved in an unaltered form.
Replacement
Occurs when an organism's bone or
shells is replaced by minerals, like calcite,
silica, pyrite, or iron. Due to the gradual
process fine details are often preserved.
Carbonization
As the organic compounds of living
creatures decay, carbon is left behind
creating a film on the rock. Fossils that
are left behind are carbonized.
Carbonization is very similar to the
transformation organic materials
undergoes during the creation of coal.
Recrystallization
Similar to replacement, recrystallization
occurs when original compounds are
replaced with a larger crystal form. The
crystal structure of the mineral changes
but the composition is the same.
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Buried organic material can be turned
into stone through the process of
petrification. Organic substances exposed
to minerals over an extended period of
time are turned into a stony material
without changing the original shape.
This process of fossilization Differs from
permineralization in that dissolved
minerals in water replace all organic
matter.
Petrification
Homework
12) Fossilization is the process that produces fossils. Mineral replacement, or petrification,
is one of the process that creates a fossil.
13) Occurs when organisms are preserved in a substance, such as amber, ice or tar,
preserves the organisms and prevents the decay of tissue.
Geological Timeline
Class Work
14) The geologic time scale to measures the relationship and timing of events that have
occurred throughout earth's history.
15) The Phanerozoic Era covers only the last 10% of Earth's history.
16) Known as the "Age of Mammals" this ear saw the largest land mammals and great
increase in the diversity of mammals due to absence of large reptiles.
Homework
17) The Phanerozoic Era covers only the last 10% of Earth's history and is split into three
eras, the Cenozoic, Mesozoic and Paleozoic.
18) The Mesozoic era was known as the Age of Reptiles. Spanning from 248 to 60 million
years ago dinosaurs ruled the land of endless fern forests.
19) During this era the continents formed the super continent of Pangaea and began to
move into the places we know them at today.
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Dating Fossils
Class Work
20) Sedimentary rock is formed by the deposition of sediment over time, usually at the
bottom of lakes or oceans. Over time the sediment layers are compressed forming solid
rock. Each layer, or strata, forms on top of the previous layer and represent different
time periods.
21) Sediments are deposited laterally in all directions until they reach a barrier. Rocks
that are now separated by are assumed to be originally continuous.
22) Sedimentary rock containing flora and fauna fossils are layered in order that can be
identified over great distances. Fossils can be identified and dated based upon the
strata they were found within.
23) Life on Earth is documented by fossils from earlier periods preserved in sedimentary
rock. The fossil record allows scientists to chronologically track the history of life on
Earth through carbon dating.
24) Carbon 14 has a half-life of 5730 year. Based on this measure the amount of carbon-14
still present in a fossil can be measured to determine its age.
Homework
25) Beds of sediment deposited in water form in horizontal layers. Changes in the layers
from geological events give clues to what has happened after deposition.
26) Sediment layers are deposited in a chronological order with the oldest rocks at the
bottom and newest rock on the top. Application of this principle allows the relative
dating of fossils based upon their position in the rock strata.
27) Paleontologist use index fossils to define and identify geologic periods. Index fossils
that commonly found and widely distributed help in dating other fossils found in the
same sedimentary layer. They provide a relative timeframe but not a specific date.
Relative dating relies on determining the order of events in a sequential fashion. This
method of dating assumes that older layers are covered by newer layers. Since fossil
evolve through time they can be used as age markers.
Similarities and Differences
Class Work
28) Studying the physiological similarities between different plants and animals reveal
how one species body parts resembles another species body parts. These similarities
provide evidence for evolution.
29) Homologies are similar structures inherited from a common ancestor.
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Evidence of Common Ancestry
30) Examining DNA sequencing, the fossil record, cellular function and embryological
development all support that life developed from a common ancestor roughly 4 billion
years ago.
31) The biochemistry of all living things on Earth is remarkably similar. Cells function
similarly in all living organisms thus supporting the Theory of Evolution and the theory
that all organisms on Earth share a common ancestor.
Homework
32) Analogous structures are features of two different species that are similar in how the
function, but the structure of the two features is different.
33) Support for a common ancestor can be found in the fossil record, anatomical
similarities, DNA comparisons and embryological development.
34) Part of an organism that have no apparent use are vestigial structures and provide
clues to past forms of the species. Similar to other mammals with tails, humans have a
tailbone but do not have a tail connected to it.
35) Comparing the gene sequences among different species reveals similarities among
very different organisms. The universal code that is identical for all known life forms
provides evidence of the theory of common descent.
Evolution
Class Work
36) Evolution is the gradual process when something changes into a different and more
complex form.
37) All organisms have a shared history and ancestry. Modern species come from a
previous form of the species that has undergone genetic modification. The most recent
last universal common ancestor (LUCA) lived 3.9 billion years ago. Analysis of the
genetic code reveals that it is all known life forms are related.
38) The movement of genes from one population to another. Migration could be pollen
carried by a bee into a new area or animals being introduced in a new destination. The
introduction of new genes where they previously did not exit create a new source of
genetic variation.
39) Natural selection is the process through which organisms adapt to their environment
to survive and produce more offspring. Natural selections begins with a variation in
traits which proves to be beneficial, increasing the chance of survival. Over time the
advantageous trait become more common and passed along to future generations.
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40) The fossil record shows the transition between species and the gradual changes
through generations.
41) Embryological development is the study of the development of organisms from
fertilized eggs to birth provides support for evolution. Vertebrates develop in very
similar ways during the early stages. These similarities and developmental patterns
demonstrate traits inherited from a common ancestor.
Homework
42) Charles Darwin speculated how natural selection and evolution was responsible for
the diversity of life on Earth. He believed that specific traits evolved over time through
natural selection.
43) Mutations are a change in the DNA that is passed along. These changes that occur can
be positive, negative or neutral. Not all mutations effect the evolution of an organisms.
Mutations can affect how an organism physiology, appearance or behavior.
44) Genetic drift is a random change in the frequency of a gene. Certain members of a
population are unable to pass along their genes, thus affecting future generations.
45) Biogeography is the study of how species are distributed across the landscape in
relation to geography and other species.
46) Human embryos form gill slits similar to fish although they never fully develop gills.
Further, four week old human embryos develop a tail, similar to other mammals. These
traits reflect the traits of a common ancestor that are no longer necessitated.
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Evidence of Common Ancestry