Please answer the following
questions from last class:
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
Name the steps your group took to classify your
“creepy critters.”
Why do scientists use dichotomous keys?
Why do we give organisms a
“scientific name”?
Sometimes the common names we give
organisms can be misleading...
Sea Lion, Antlion, Lion...
Are these related?
What kinds of organisms are these?
Sea Horse?
Sea Monkey?
Spider Monkey?
Scientists had to come up with a way to name
organisms that more clearly described their
physiology, and their relationship to others...
Scientific Naming

Just like Aristotle and Linnaeus, we use
binomial nomenclature when assigning names
to organisms. What does this mean?
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The first name is the genus that the organism
belongs to.

It should begin with a capital letter and be
written in Italics (Or underlined when italics
are not possible.)

The genus tells us which species are closely
related
The second name is the organism's species
classification.

It should also be written in Italics (or
underlined when italics are not possible), and
in lower case letters.

We use Latin when naming organisms because
it is the universal language of science.
Creating Dichotomous Keys

Dichotomous means to divide into 2 parts

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So each question must offer only 2 choices
Start with the most general question to split all
of your items into 2 groups
Then work with each of your smaller groups one
at a time to divide into 2 more specific groups

It will help to create a “spider key”

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When you cannot divide a group any further (it
contains only items that are identical), write the
name of that item on the key.
Now use your spider key to create a
dichotomous key
Each time you split a group into 2 smaller
groups, you can create 2 options for your key
(one for each group)

Conquer one group at a time
Please answer the following
questions from yesterday's class
What Genus to Homo sapiens belong to?
What is the first step to creating a dichotomous
key?
Assignment details
Create a Dichotomous Key for organisms that you
can find locally (in your community) or regionally
(in this area of the world)
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•
•
You can choose 4 – 8 organisms
You must use scientific names for your organisms
(if you can't find them, come speak to me)
You must bring in a sample or picture of one of
your organisms so we can see if your key works
This is to be handed in Monday, December 6,
2010