NAME:
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LAB #22H – Classifying Critters
OBJECTIVES:
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Develop a classification key to identify several organisms.
Recognize that species are classified into a hierarchical taxonomic system (kingdom, phylum,
class, order, family, genus, species) based on morphological, behavioral, and molecular
similarities.
MATERIALS:
Bag with assorted “critters”, paper, ruler, pencil, textbook, outside resources.
PROCEDURE:
1. Empty your bag of critters onto your lab table.
2. Examine each of the critters carefully.
3. Choose a characteristic to separate the critters into two groups of approximately equal numbers.
4. In OBSERVATIONS, make a branching chart similar to the one in Figure 1 to show how you
divided the critters. Write the characteristic you used to divide the group on top of the lines in
your chart corresponding to lines A1 and A2. Write the numbers of the critters under the lines in
your chart corresponding to lines A1 and A2.
D1
B1
D2
E1
A1
B2
E2
F1
All critters
Figure 1
C1
F2
G1
A2
C2
G2
5. Now choose a characteristic to divide the critters in A1 into 2 subgroups. Write the characteristic
you used to divide the A1 group on top of the lines in your chart corresponding to lines B1 and B2.
Write the numbers of the critters under the lines in your chart corresponding to lines B1 and B2.
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6. Separate the critters in A2 into 2 subgroups. Write the characteristic you used to divide the A2
group on top of the lines in your chart corresponding to lines C1 and C2. Write the numbers of
the critters under the lines in your chart corresponding to lines C1 and C2.
7. Continue dividing each group of critters until each critter is separated from all of the others. On
your chart, continue to write both the characteristic applied and the numbers of the critters.
NOTE: Your chart may not contain all of the branches shown in Figure 1. Also, you might need to
extend your chart by adding branches not shown in Figure 1. REMEMBER: Only 2 branches per
line!
OBSERVATIONS:
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ANALYSIS/CONCLUSIONS:
1. How is this investigation similar to the way in which biologists classify organisms?
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2. People can use classification systems to separate many things. Organize the following items in two
different ways using similarities and differences. Explain the rationale for your system.
taco shells
rice
lettuce
peas
kidney beans
corn
hot dog
muffin
hamburger
bread
steak
spinach
potatoes
green beans
sausages
tomatoes
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3. Classify each of the following organisms into its proper kingdom by writing the current kingdom
after each organism.
amoeba _____________
maple tree _____________
pine tree _____________
E. coli
_____________
dog
_____________
eagle
_____________
octopus _____________
bread mold _____________
humans _____________
paramecium __________
mushrooms _____________
grass
_____________
4. Write the taxonomic classification hierarchy in the correct order from least specific to most
specific.
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5. What characteristic did you find most useful for classifying the critters? Explain your reasoning.
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6. Why should terms like tall, short, large, or small be avoided when describing traits of organisms?
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7. How does classification help you to better understand organisms? Explain your answer.
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8. Trees are usually identified by the characteristics of their leaves. Suggest 3 ways in which trees
could be identified during winter when they have no leaves.
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9. Suppose you wanted to identify and classify all birds that came to your bird feeder one summer day.
What are some common characteristics you would use in classifying the birds?
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10. Almost immediately after the invention of the microscope, taxonomists began to use it in their
work. Why might a microscope be useful to a taxonomist?
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10. Cladograms are another way to show relationships among organisms. Convert the chart from your
observations into a vertical cladogram. See the example below.
http://images.search.yahoo.com/search/images?p=cladogram%20chordates
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