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HOMOLOGOUS STRUCTURES (definition): ______________________________________________________________________________________
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1. Carefully examine the drawings of the bones shown in Figure 1 on the next page. Look for similarities among the various animals. a. Color each part of the human arm a different color. (Note: All bones of the wrist should be a single color; all the bones of the hand should be a different single color, etc.) Then color the corresponding bone in each of the other animals the same color as the human bone. b. Describe the function of each structure below:
ANIMAL FUNCTION OF STRUCTURE
HUMAN
WHALE
CAT
BAT
BIRD
CROCODILE c. Are the bones arranged in a similar way in each animal? Explain.
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ANALYSIS AND INTERPRETATIONS
1.
Explain why the homologous structures are evidence of evolutionary relationships.
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2.
Re-define this type of evidence for evolution that you have studied in this lab in your own words.
HOMOLOGOUS STRUCTURES - ______________________________________________________________________________________________________
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ANALOGOUS STRUCTURES (definition): ________________________________________________________________________________________
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1. Examine the butterfly wing and the bird wing shown in Figure 2. a. What function do these structures share? ____________________________________________________________________________ b. How are these structures different? ___________________________________________________________________________________
________________________________________________________________________________________________________________________________ c. Do birds and insects share any structural (elements inside the wing) similarities that would suggest they are closely related taxonomically? Explain.
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VESTIGIAL STRUCTURES (definition): __________________________________________________________________________________________
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Gradual changes have occurred through time that have in some cases reduced or removed the function of some body structures and organs. The penguin's wings and the leg bones of snakes are examples of this phenomenon.
1. The cavefish and minnow shown in Figure 3 are related, but the cavefish is blind. a. Explain why eyesight is not an important adaptation to life in a cave.
________________________________________________________________________________________________________________________________ b. What do you think has become the most important adaptation of the cavefish (think about senses)? (explain your answer)
________________________________________________________________________________________________________________________________ c. What about the internal structure of the cavefish and minnow suggest common ancestry?
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2. Read the list of human vestigial structures shown in Table 1. a. Suggest a possible function for each structure and explain why it became vestigial. Record your answers in
Table 1. the table.
STRUCTURE POSSIBLE FUNCTION WHY VESTIGIAL? appendix (digests leaves in koala bears) coccyx (tail bones) muscles that move ears muscles that make hair stand up little toe wisdom teeth
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ANALYSIS AND INTERPRETATIONS
1.
Explain the evolutionary relationship between the fin of a fish and the flipper of a whale.
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2.
List two structures (not from Table 1) that you think are vestigial and explain why.
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2. _____________________________________________________________________________________________________________________________
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Re-define these different types of evidence for evolution that you have studied in this lab in your own words.
2. ANALOGOUS STRUCTURES - __________________________________________________________________________________________
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3. VESTIGIAL ORGANS - ___________________________________________________________________________________________________
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Procedure Set A:
1) Spread the cards with the nonsense syllables on the table and determine the correct sequence of the eight cards by comparing letters that are common to multiple cards and, therefore, overlap. The first card in the sequence has
"Card 1, Set A" in the lower left-hand corner and represents the bottom of the sequence. If the letters "T" and "C" represent fossils in the oldest rock layer, they are the oldest fossils, or the first fossils formed in this sequence of rock layers.
2) Now, look for a card that has either a "T" or "C" written on it. Since this card has a common letter with the first card, it must go on top of the "TC" card. The fossils represented by the letters on this card are "younger" than the "T" or "C" fossils on the "TC" card. Sequence the remaining cards by using the same process. When you finish, you should have a vertical stack of cards with the top card representing the youngest fossils of this rock sequence and the "TC" card at the bottom of the stack representing the oldest fossils.
Part A Interpretation Questions:
1.
After you have arranged the cards in order, write your sequence of letters below. Starting with the top card, the letters should be in order from oldest to youngest. Have your teacher check your sequence.
How do you know that "X" is older than "M"? "
Explain why "D" in the rock layer represented by DM is the same age as "M."
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Explain why "D" in the rock layer represented by OXD is older than "D" in the rock layer represented by DM.
Procedure Set B:
1) Carefully examine the second set of cards which have sketches of fossils on them. Each card represents a particular rock layer with a collection of fossils that are found in that particular rock stratum. Figure 6. gives some background information on the individual marine fossils.
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2) The oldest rock layer is marked with the letter "M" in the lower left-hand corner. The letters on the other cards have no significance to the sequencing procedure and should be ignored at this time. Find a rock layer that has at least one of the fossils you found in the oldest rock layer. This rock layer would be younger as indicated by the appearance of new fossils in the rock stratum. Keep in mind that extinction is forever. Once an organism disappears from the sequence it cannot reappear later. Use this information to sequence the cards in a vertical stack of fossils in rock strata and arrange them from oldest to youngest
Part B Interpretation Questions:
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Using the letters printed in the lower left-hand corner of each card, write the sequence of letters from the youngest layer to the oldest layer below. Have your teacher check your sequence.
6.
Which fossil organism was the most recent to evolve? How do you know?
Which fossil organism(s) were the most ancient to evolve? How do you know?
In what kinds of rocks (sedimentary, igneous, metamorphic) might you find the fossils from this activity?
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Do all rock types lead to fossil formation? Explain.
Using the paper embryos, arrange all of the organisms in order from earliest developmental stage (Stage 1) to latest developmental stage (Stage 3) on the proper column of the sheet provided. Check your embryos before you start on the analysis and interpretation questions.
ANALYSIS AND INTERPRETATIONS
1.
Why did you order the drawings the way you did? What are some of the similarities and differences between the drawings?
2.
During which stage of embryonic development do the organisms have the most in common? Give 1 explanation for why you think they share so many similarities.
3.
How does this lab relate to common descent?
4.
Which stage is the most difficult to organize? Why?
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What stage was the least difficult to organize? Why?
6.
Based on the similarity of the embryos, which 2 organisms would you predict are most closely related? Explain.
7.
Which organism do you think would have the most DNA in common with humans? Explain.
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