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Name: _______________
Date: _______
Period: _____
Fossil Record
Paleontologist: A scientist studies fossils for clues of biological change as it relates to
geological change in the Earth’s history.
Strata: layers of the Earth’s crust
Observe the beaker of strata at your lab station and the image above.
1. What is the relationship between the depth of Earth’s strata and how much time has
passed?
The deeper the layer of strata, the older rock and fossils in the rock are.
Evolutionary concept: Fossils found lower in the earth’s crust can be compared to newer
fossils above it to see change overtime.
Observe the dated fossils at the lab station.
2. What differences do you see in the same species over different periods of time?
Correct fossils were not available- Ignore this question
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Name: _______________
Date: _______
Period: _____
This is a series of skulls and front leg fossils of organisms believed to be ancestors of the
modern-day horse.
2. Give two similarities between each of the skulls that might lead to the conclusion
that these are all related species.
Possible answers: similar skull shape, jaw shape, nose bump, and eye holes
3. What is the most significant change in skull anatomy (form) that occurred from the
dawn horse to the modern horse?
Skull size became bigger
4. What is the most significant change in leg anatomy (form) that occurred from the
dawn horse to the modern horse?
Possible answers: Legs got longer; legs went from having feet with three toes to having
hooves.
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Name: _______________
Date: _______
Period: _____
Embryology
Developmental biologist: A scientist that studies how the processes of growth and
development occur and change over time.
Embryo: Earliest stage of development for an unborn eukaryote.
Organisms that are closely related may also have physical similarities before they are even
born! Take a look at the six different embryos below:
Use the chart to hypothesize which embryo is from each of the above organisms by
matching the letter of the embryo with the species:
Species
Embryo
(letter)
Species
Embryo
(letter)
Human
Chicken
Rabbit
F
D
E
Tortoise
Salamander
Fish
C
B
A
These are older, more developed embryos from the same organisms.
Use the chart to hypothesize which embryo is from each of the above organisms by
matching the letter of the embryo with the species.
Species
Embryo
(letter)
Species
Embryo
(letter)
Human
F
Tortoise
C
Chicken
Rabbit
D
E
Salamander
Fish
B
A
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Name: _______________
Date: _______
Period: _____
These are embryos at their most advanced stage, shortly before birth.
Describe this change by answering the questions.
1.
Look again at the six embryos in their earliest stages. Describe the patterns you
see. What physical similarities exist between each of the embryos? (name at least 3)
Possible answers: tail, eye-hole, ear hole, bumpy hand-like structures
2.
The human embryo was letter F. Which organism’s embryo became different from
the human embryo the earliest on in development?
fish
3.
What does this say about the relatedness of this organism and humans?
fish and humans are related, but by a big distance
4.
Which organism’s embryo was the same as the human embryo for the longest
period during development?
Rabbit
5.
What does this say about the relatedness of this organism and humans?
Rabbits and humans are closely related
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Name: _______________
Date: _______
Period: _____
Comparative Anatomy
Evolutionary biologist: A scientist that studies the origins and relatedness of living
organisms. They look at homologous and vestigial structures.
Shown below are images of the skeletal structure of the front limbs of 6 animals: human,
crocodile, whale, cat, bird, and bat. Each animal has a similar set of bones. Color code each
of the bones and mark them in this key:
Humerus [ ]
Carpals
[ ]
Ulna
[ ]
Metacarpals
[
]
Radius
[
Phalanges
[
]
]
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Name: _______________
Date: _______
Period: _____
For each animal, indicate what type of movement this front limb is responsible for.
Animal
Human
Whale
Primary Functions
Using tools, picking up and holding objects
swim
Cat
Climb, catch mice
Bat
Fly, wrap up and sleep
Bird
fly
Crocodile
Swim, walking in swamp
Compare the skeletal (bone) structure of each limb to the human arm. Relate the
differences you see in form to the differences in function.
Animal
Comparison to Human Arm in Form
Comparison to Human Arm in Function
Whale
Whale has a much shorter and thicker
humerus, radius, and ulna. Much
longer metacarpals. Thumb has been
shortened to a stub.
Shorter, smaller, fewer phalanges, and
metacarpals, larger carpal
The whale fin needs to be longer to help in
movement through water. Thumbs are not
necessary, as the fins are not used for
grasping.
Catching mice, climbing
Cat
Bat
Flying and wrapping up to sleep
Longer phalanges
Bird
Single phalange, metacarpal
Carpal is shallow (hole in it)
Crocodile
Need light bones to fly
Walking and swimming in swamp
Long phalange, short ulna, radius,
humerus
Homologous structures: Similar structures that perform different functions. These are
seen in organisms that are closely related.
1. Give an example of a homologous structure from this activity:
Possible answers: ulna, radius, carpal, metacarpal, phalange, humerus
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Name: _______________
Date: _______
Period: _____
Vestigial structures: remnant structures that were once important in the organism’s
ancestors, but are no longer used in the same way.
Below are vestigial structures found in humans. For each, hypothesize what its function
may have been.
Wisdom teeth larger jaw, replace rotten teeth
Appendix  Supplies bacteria to gut to digest leaves
Muscles for moving ear used for directional hearing (hear from different directions)
Body hair body covered in lots of hair for warmth
Little toe used for balance
2. Give an example of a vestigial structure from this activity:
Possible answers: appendix, muscles to move ear, body hair, little toe, wisdom teeth
3. How do homologous and vestigial structures suggest an evolutionary relationship
between species?
Homologous structures show that humans, cats, bats, crocodiles, birds, and whales all have
similar bones with different functions, so they must have a common ancestor.
Vestigial structures tell us that humans have structures leftover from an ancient ancestor
that are no longer used for their original purpose.
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Name: _______________
Date: _______
Period: _____
Molecular (DNA) Biology
Molecular (DNA) biologist: A scientist that studies the molecular basis of biological
activity, particularly DNA sequences and biochemistry.
Below are sequences of letters that stand for portions of the genes that code for α and β
hemoglobin (blood) proteins in different primates.
Compare the DNA sequences from the α hemoglobin for the thick-tailed bushed baby and
humans. Circle any differences in base pairs from the human sequence and record the
total differences in the data table on this page.
Primate Animal
Number of base pair differences for
α hemoglobin compared to humans
Number of base pair differences for
β hemoglobin compared to humans
Human
0
0
Thick-tailed
bush baby
94
X
Chimpanzee
X
1
Gorilla
X
5
Orangutan
X
106
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Name: _______________
Date: _______
Period: _____
Compare the DNA sequences for β hemoglobin for the chimpanzee, gorilla, human, and
orangutan. Circle any differences in base pairs from the human sequence and record total
differences in the data table on the last page.
1. Based on the α hemoglobin and β hemoglobin data, which organism is most closely
related to humans?
chimpanzee
2. Do any of the organisms have the same number of differences from human α
hemoglobin or β hemoglobin? In situations like this, how might you decide which is
more closely related to humans?
No, all primates have a different number of differences in base pairs from humans.
Chimpanzees have one difference, then gorillas are the next closest to humans with 5 DNA
sequence differences.
3. How does a similar DNA sequence suggest an evolutionary relationship between
species?
Similar DNA sequences between organisms means that they share a more common ancestor
that is no longer living. The more distant the ancestor, the more different their DNA sequences
will be.
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