Download 10-Evidence for Evolution 4

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Evidence for Evolution
Introduction: “You look just like your mother!” “He has his father’s eyes!” These comments that refer to
the similarities and differences between parents and their children are heard often in conversation.
These similar traits are due to the genetic material that children inherit from their parents. As humans
we are sometimes fortunate enough to have three or four generations sitting in a room at one time, and
we can see the similarities from generation to generation. But how much do you look like your ancestors
from 100 generations ago, 1000 generations ago or more? How much of your DNA did you inherit from
those ancestors? What traits do you share with them?
1. The above diagram is a family tree. How would you describe the organisms in the second row of
the diagram that are connected to their parents by a line?
2. Identify the three members of the family that married in by placing a * next to their figures.
3. Consider the third generation of organisms.
a. How many of the organisms in the third generation exhibit one or more traits identical
to one of the grandparents?
b. How many of the organisms in the third generation exhibit one or more traits that are
not shown in one of the grandparents?
c. Describe three methods by which these traits may have been introduced into the family
tree.
Comparative Anatomy
Number of Bones Found in the Forelimbs of Selected Animals
Bone Name & Position
Human
Dog
Bird
Humerus – closest to body
1
1
1
Radius & Ulna
2 separate 2 separate 2 separate
Carpals (wrist)
8
6
1-2
Metacarpals & Phalanges (fingers) 5
5
3
Whale
11
2 separate
6
5
1. Label the bones in each animal forelimb in the diagram above.
2. List the ways that each animal uses their forelimb.
3. List two or more similarities in the bone structure of the four animals shown.
4. List three or more differences in the bone structure of the four animals shown.
5. What do the similarities among the forelimb bone arrangements of these diverse animals imply
about their ancestry?
6. Which two animals would you predict to have the most DNA sequences in common? Explain.
7. Study the bone arrangement in the bird and the whale. Propose an explanation for the similarity
of elongated bone arrangement in the lower parts of the forelimb (metacarpals and phalanges),
given the differences in the animals.
DNA Comparison
Extensive research has been done to find similarities and differences in the DNA sequences of different
animals. This work is very difficult and time consuming, but it can help biologists determine the
evolutionary ancestry of a species.
Organism Pair
human – human
human – chimpanzees
human – mice
human – chickens
human – slugs
human – bananas
Percentage of
DNA Similarity
99.5%
97%
85%
75%
70%
50%
1. Which pair of organisms most likely shares a recent common ancestor? Support your answer.
2. Suppose another organism, organism X is discovered. Suggest how scientists would use DNA
comparison to classify organism X.
3. Could you use this data to compare how similar mice are to chickens? Explain how you could, or
how why you could not.
Comparing Amino Acid Sequences
Scientists use differences in amino acid sequences in proteins to determine evolutionary relationships of
living species. You are to compare representative short sequences of amino acids of a protein among
other groups of primates to determine their evolutionary history.
1. Which primate is most closely related to humans? Least closely related?
2. Construct a diagram of primate evolutionary relationships that most closely fits your results.
3. Why are amino acid sequences a reliable source to compare similar species?
Baboon Chimp Lemur Gorilla Human
ASN
SER
ALA
SER
SER
THR
THR
THR
THR
THR
THR
ALA
SER
THR
ALA
GLY
GLY
GLY
GLY
GLY
ASP
ASP
GLU
ASP
ASP
GLU
GLU
LYS
GLU
GLU
VAL
VAL
VAL
VAL
VAL
ASP
GLU
GLU
THR
GLU
ASP
ASP
ASP
ASP
ASP
SER
THR
SER
THR
THR
PRO
PRO
PRO
PRO
PRO
GLY
GLY
GLY
GLY
GLY
GLY
GLY
SER
GLY
GLY
ASN
ALA
HIS
ALA
ALA
ASN
ASN
ASN
ASN
ASN
Data Table
Primate
Baboon
Chimpanzee
Lemur
Gorilla
Amino acids different
from humans
%
difference