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Using a Dichotomous Key, Part 1

Do the following lab activity, "Using a Dichotomous Key." The instructions for this lab are below, and this lab must be done in the Biology Learning Center. There are worksheets for this activity in your worksheet packet. When you have completed each step of the activity, take the results to the front desk inthe Biology Learning Center for lab points.

Equipment and Supplies:
  • Kit #76 and #82
  • Dichotomous Key (a copy is located underneath Model S (the cat skeleton) or it can be printed out from the links below)

In this lab activity, you first will use a dichotomous key to classify some “mystery” organisms to the phylum level and then to the phylum and class level.

Dichotomous keys are very useful tools because they guide you through the most pertinent characteristics of all the marine phyla (or classes, etc.) to help you determine to what phyla your mysterious organism belongs.

To do this lab, you will need copies of the dichotomous key for phyla and one for phyla and classes. The dichotomous key for marine phyla can be printed out by following this link and the key for phyla and classes by following this link. However, these are BIG files and you may become quite frustrated if you are using a modem or don’t have a lot of memory on your computer. So, if that is the case, come up to the front desk and we will give you your very own printouts of the two dichotomous keys.

You might be wondering, "How do I pronounce that really long, scary looking word: dichotomous?" It's not that hard:

"Die-Cot-O-Mus" (the "mus" is like "bus" but with an "m")

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