Download Evidence for Evolution: Evolutionary Biologist

Name_______________________________
Evidence for Evolution
Paleontology and Geology: Stratum layers
Summarize what the graphic below tells you about the relationship between the relative age of fossils and
their position in the ground. Assume that the top of the graphic is nearer to the surface of the Earth than
the bottom.
_____________________________________________________________________________________
Relative
Dating
The following graphics show how paleontologists use radiocarbon dating to determine the absolute age
of rocks and fossils. Use the graphics to answer the questions below.
Living organism
Like all living organisms,
this mollusk is absorbing
12
C and 14C from the
environment. The ratio of
14
C to 12C is constant at
1:1 x 1012.
Dead organism
Once the mollusk dies, it
no longer absorbs carbon.
The radioactive 14C
begins to decay and the
amount of 14C in the
mollusk shell decreases,
while the amount of 12C
remains the same.
History
Because half the 14C
decays every 5600 years,
the mollusk fossil's age
can be determined by
finding the ratio of 14C to
12
C in the fossil and
1. While an organism is living, which of the following is true?
14
12
12
14
it with the
a. There is more C than C.
c. The amounts of C andcomparing
C are equal.
12
14
b. There is more C than C.
d. None of these are true. ratio in living organisms.
2.
14
C dating is most successful on organisms that are
a. less than 50 years old.
b. less than 5,000 years old.
c. less than 50,000 years old.
d. less than 50 million years old.
3. Suppose an organism dies containing 1000 g of 14C, and half of the 14C decays every 5,600 years, how much 14C
will be after 11,200 years?
a. 500 g
c. 11,200 g
b. 250 g
d. 5, 600 g
4. How many thousands of years will it take for a sample starting with 1000 g of 14C to get 125 g of 14C?
a. 11.2
c. 22.4
b. 16.8
d. 28.0
5.
14
C dating finds the age of a fossil by
a. finding the difference between 12C and 14C.
b. adding the amount of 12C with the amount of 14C
c. finding how much 14C there is at the present time.
d. finding the ratio of 14C to 12C
6. Does carbon-dating directly or indirectly determine the age of a fossil? ______________________________
Evidence for Evolution: Evolutionary Biologist
Evolutionary biologists study how different organisms have evolved over time. There are many
different ways that scientists can contribute data for organisms changing over time. One of the ways
evolutionary biologists can study this is by comparing structures of different organisms.
Go to http://evolution.berkeley.edu/evolibrary/article/similarity_hs_01. Complete this module and
answer the questions below in order to understand some of the evidence Evolutionary Biologists look at.
(Note there are not questions for every page on the module, but the questions are in order.)
1. What is the difference between a homology and an analogy?
Homologous Structures
2. Color in the picture below to show the bones that homologous between these different species.
3. Label the organism that each limb comes from.
Organism:_______________
____
Organism:________________
___
Organism:________________
___
Organism:_______________
____
4. Explain, in a few sentences, why these structures might provide evidence for evolution.
Analogous Structures:
5. Give an example of an analogous structure.
6. Do analogous structures comes from a common ancestor?
7. How do analogous structures evolve?
8. Summarize how Evolutionary Biologists determine whether a structure is a homology or an analogy.
9. Is a Panda’s thumb homologous or analogous to a human’s thumb? Why? (Open a new window and go
to http://evolution.berkeley.edu/evolibrary/article/side_0_0/analogy_06 )
10. Are the wings of the of sugar gliders and flying squirrels homologous or analogous structures?
Vestigial Structures:
Look at the following structures. All of these organisms have vestigial structures. After looking at these
pictures, define a vestigial structure:
Blind mole rat has eyes, which
are covered by layer of skin
Ostriches have wings, yet they
can’t fly
Leg bones can be found in a whale
11. Define VESTIGIAL STRUCTURES:
12. Why do you think organisms have these structures? (HINT: think about what we’re studying)
Evidence for Evolution: Embryology
The study of one type of evidence of evolution is called embryology, the study of
embryos. An embryo is an unborn (or unhatched) animal or human young in its earliest
phases. Embryos of many different kinds of animals: mammals, birds, reptiles, fish, etc.
look very similar and it is often difficult to tell them apart. Many traits of one type of
animal appear in the embryo of another type of animal. For example, fish embryos and
human embryos both have gill slits. In fish they develop into gills, but in humans they
disappear before birth. This shows that the animals are similar and that they develop
similarly, implying that they are related, have common ancestors and that they started
out the same, gradually evolving different traits, but that the basic plan for a
creature's beginning remains the same.
Your teacher will give you an embryonic puzzle. It is your job to put the puzzle together. Hints:
 There are 5 different animals.
 Each animal has an early, middle, and late embryonic development piece.
Once completed, answer the following questions:
1. Try and identify the five different animals. After you do so, check with the key.
Hypothesis: Animal Type
Actual: Animal Type
a.
a.
b.
b.
c.
c.
d.
d.
e.
e.
2. Describe three similarities of the embryo structures during early developmental stages of different
organisms?
a.
b.
c.
3. Describe three similarities of the embryo structures during late developmental stages of different
organisms?
a.
b.
c.
4. Describe three differences of the embryo structures during late developmental stages of different
organisms?
a.
b.
c.
5. Identify which organisms are more closely related based on embryological evidence, and site
evidence for your inference.
Evidence for Evolution: Molecular Biologist
Deoxyribonucleic acid (DNA) codes for proteins that your body needs
to live. One of those proteins is the hemoglobin protein that is found in your
blood. This protein carries oxygen and carbon dioxide as they circulate in your bloodstream.
Other animals’ blood also contains hemoglobin, but not all of these proteins are identical. The
differences between the hemoglobin of humans and other animals are caused by differences in
the DNA that codes for them.
The scientists who study biological molecules such as DNA or proteins are known as
molecular biologists. DNA and proteins are ideal molecules to study when looking for
evolutionary relationships between organisms because changes in their structure (mutations in
DNA) pile up through time. The more closely two organisms are related, the less time that has
elapsed since they shared a common ancestor. Less time means a fewer number of differences
(mutations) between each organism. If two organisms are very distantly related, we would
expect a great number of differences in their DNA since more time has passed to allow for more
mutations to occur. With the advancement of DNA technology, scientists have been able to
compare these ‘genetic documents” that relates an organism’s evolutionary history.
In the following activity, you will use this knowledge of DNA and the evidence it can
provide to determine the evolutionary relationships between humans and some of our primate
relatives. (Note that you could determine evolutionary relationships by comparing the amino acid
sequences of the same protein found in different organisms.)
Procedure:
1. Observe the segments of the hemoglobin gene for the four primates on the next page.
2. Circle/highlight all the letters in the chimpanzee, gorilla, and orangutan genes that are
different from the human gene. Be sure to go through all three segments (which are
all one piece of DNA)
3. Total the differences in the data table below.
4. Calculate the % similarity between the ape and the human genes.
5. Answer the analysis questions.
Table 1: DNA variation in Chimpanzees, Gorillas, and Orangutans compared to Humans
Differences in
Hemoglobin Gene
Chimpanzee
Gorilla
Orangutan
# Differences
# Similarities
% Similarity
(180 - # Differences)
(# Similarities / 180) x 100
Analysis Questions: Answer using complete thoughts and complete sentences. Write
neatly using PEN or type your answers on a separate piece of paper.
1. Explain, citing evidence, which of the apes is most closely related to humans.
2. Explain, citing evidence, which of the apes is most distantly related to humans.
3. What is the relationship between time and the number of mutations that are present in the
DNA of an organism?
4. Does the data in Table 2 (below) support your conclusions made using Table 1 data?
Explain why or why not.
Table 2: Time of Last Common Ancestor between Primate and Humans
Primate
Millions of Years Since Last
Human Common Ancestor
Chimpanzee
7
Gorilla
10
Orangutan
12
Gibbon
15
5. If a segment of gibbon DNA were sampled, what do you believe the % similarity to humans
might be? (Give an approximation)
6. Describe how molecular biologists can give evidence for evolution.
Describe how each of these scientists have contributed data that supports evolution!
Write, Draw, and Color!
An
embryologist
contributes