Creating a Dichotomous Key s1

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Creating a DichotOmous Key Classification is a specific way of organizing information so that it can be more useful. There are as many as 100 million species of living things on earth today. Classification of these organisms helps us see similarities and differences amongst the biotic world. Scientists have classified millions of living species based on their physical characteristics and they have given a unique name to each unique species. This classification is important in understanding the natural world. All of the information known about living species is used to organize them into a sort of family tree, which helps us to see the similarities and differences that exist in the living things all around us. The scientists who classify living things record their classifications so that later, others who encounter a certain species will be able to identify it in the same way. Making sure that two scientists are referring to the same thing when using a certain name is important for clear communication. Dichotomous keys help guide scientists toward identification so classifications can be shared and used mutually. A dichotomous key is a guide for classification and identification, somewhat like a map through a classification system that was previously developed. Dichotomous comes from the Greek root dich-, meaning "two" and temnein, meaning "to cut". Dichotomous keys ask a series of questions about the object to be identified; each question has only two possible answers, and the answer in reference to the certain object will lead the user in one of the two possible directions laid out by the answer. Dichotomous keys can be developed to identify anything in any sort of classification. Your challenge as a group is to develop a dichotomous key in order to better understand a dichotomous key, how it works, and the diversity of life.

Above is an example of a dichotomous key. For your challenge, pick ten organisms from the Pond Life book. Choose any five as long as at least three kingdoms are represented in your key. The first part of creating a key is to create a dichotomy that will send the reader to the area of the key that is specific to a kingdom. Once in the correct kingdom, the reader can identify that specific type of fungus, protozoan, animal, etc.

EXAMPLE 1. a. The cells are prokaryotic………………..Bacteria b. The cells are eukaryotic…………………go to 2 2.a. The organism is unicellular…………….Protista b. The organism is multicellular…………...go to 3 3. a. The organism You will be graded on the ability of your classmates and instructor to use your key to correctly identify one of your ten organisms! GOOD LUCK

Analysis Questions 1. Is it possible to create more than one dichotomous key for classifying and identifying the same group of objects? Why or why not?

2. When two people use the same dichotomous key to identify the same object, is it possible (should it be possible) for them to have different final answers?

3. Why are classification and identification important?

4. Explain the binomial nomenclature system.

CITATION Text from: http://www.saskschools.ca/curr_content/biology20/unit3/unit3_mod1_les2.htm Image: http://www.ekcsk12.org/faculty/jbuckley/leclass/practicemidterm6.htm