NAME _____________________
DATE _____________________
SCIENCE PERIOD # __________
TWO COLUMN NOTES
CHAPTER 5 SECTION 3
OTHER EVIDENCE FOR EVOLUTION
Similarities in body
structure
Long ago scientists would compare the body structures of different species to see
about which species were related through evolution.
They found that fishes, amphibians, reptiles, birds and mammals are all related by
evolution and grouped into the group vertebrates- they all have a
_______________ a common body part.
If you look at the body parts (page 160) of the bird, dolphin, and dog you will see
that the structures are quite similar and means that they all evolved from a
common ancestor. Scientists call similar structures that have evolved from a
common ancestor __________________________ ________________ .
An interesting fact is that the fossils of whales show they had ________________
and walked on the _____________ .
Similarities in early
development
Look at figure 14 on page 161.
These are pictures of a developing chicken , rat and turtle. They all look alike. But
scientists have determined that the _________ and the _____________ are most
closely related.
Similarities in DNA
Recall that genes are made up of DNA and the sequence of DNA codes for the
production of different proteins. By comparing the sequence (order) of DNA in a
species scientists can infer which species are more closely ____________ .
Combining The
Evidence
Scientists have combined evidence from __________ , ________ _____________
,early development and _______ sequencing to determine the evolutionary
relationships between species.
A _____________ ____________ helps scientists to see the relationships between
different species. It allows scientists to see how different species are related.
SECTION REVIEW
1. Name three types of evidence from modern-day organisms that scientists
use to determine evolutionary relationships.
a. __________________________
b. ______________________________
c. _____________________________
2. What are Homologous structures?
3. What information did scientists learn by comparing the early
developmental stages of turtles, chickens, and rats?
( Which ones are more closely related)
4. If two species are closely related, what would you expect a comparison of
their DNA base sequences to reveal?
5. Most scientists today consider similarities in DNA to be the best indicator
of how closely two species are related.
Why do you think this is the case?
How do fossils
form
First you must define a fossil
____________________________________________________________________
____________________________________________________________________
_____________________________
Most fossils are not complete organisms. Usually the soft parts are eaten or decay.
Usually the __________________ parts such as the _______________ or
_____________ remain. Plants can also be fossils. The parts of plants that are often
preserved as fossils include the _______________ , ___________________ ,
______________ and seeds.
Most fossils form when organisms that die become buried in _______________ .
Petrified fossils
Sometimes remains that are buried in sediments are actually changed into
____________ .
What happens is the organisms remains are replaced by __________________
In the sedimentary rock.
Molds
Sometimes hard parts of dead organisms are buried in sediment. The hard parts are
slowly dissolved . what is left is a ________ __________ in the shape of the
organism.
Casts
Sometimes the mold (hollow space becomes filled with hardened ____________ .
Preserved
Remains
Sometimes the remains are preserved in some material.
These materials include
1.____________________
2. _____________________
3.______________________
Determining a
fossils age
Relative dating
Sometimes the actual age of a fossil is unknown. But scientists can determine which
fossil is older than the other because of the _____________ of the fossil in relation
to another fossil. Usually the fossil that is on top is ______________ than a fossil on
the bottom.
Absolute
dating
This type of dating determines the _____________ age of a fossil. These fossils are
usually found near a sample of _____________ material. The scientists can
determine the ________ _________ of the radioactive material. The half life is how
long it takes for _____________ of the radioactive material to decay (change into )
another substance.
The table below shows radioactive material x. It has a half life of 1,000 years. As you
know that means that half of material x will decay into material y in 1,000 years.
Using this knowledge determine the ages of the three samples.
Material x
Material Y
Age
10 grams
0 grams
5 grams
5 grams
2.5 grams
7.5 grams
What do fossils
Reveal
The millions of fossils that scientists have collected are called the
_______________ _________________ .
If they have a fossil of a species but cannot find any living members of the species
then scientists say the species is _______________ .
How Fast Does
Evolution
Occur
We have defined EVOLUTION as a
______________________________________________________ in response to a
change in the environment.
Gradualism is defined as a
____________________________________________________________________
____________________________________________________
Punctuated Equilibria- is defined as a
____________________________________________________________________
_____________________________________________ in response to a rapid
cataclysmic change in the environment.
Scientists now believe which one is right
SECTION REVIEW
1. Describe how fossils formed in sedimentary rock.
2. Explain the process of absolute dating.
3. What is the fossil record?
What does the fossil record reveal about extinct species?
4. How are the theories of gradualism and punctuated equilibria similar?
How are they different?