Dichotomous Keys 4.3

Dichotomous Keys

Dichotomous Keys

What is a Dichotomous Key?

A dichotomous key is a series of "yes or no" questions that allow you to correctly identify any living organism, such as plant or animal, or non-living thing, like rocks. The word dichotomous means divided into two parts.

When following a dichotomous key you always answer with "yes" or "no" and follow the instructions.

Following a dichotomous key should be simple. Answer "yes" or "no" and follow along.
For example, comparing a turtle to a tortoise:

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Identifying an Organism

1. Does the animal have a flipper or foot? If it has a flipper go to 2. If it has a foot go to 3.

2. The animal is a turtle.

3. The animal is a tortoise.
   

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Steps to Identify an Organism

​There are many other differences between a turtle and tortoise that can be observed by this picture! The examples given are just ONE of many ways of identifying a turtle or tortoise!

Follow along to identify the organism on the dichotomous key by answering "yes" or "no" starting with 1!

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Dichotomous Key Example

Multiple Choice

Following this dichotomous key, identify the insect labeled "B"

• Ladybug

• Firefly

• Dragonfly

• Bee

Multiple Choice

Following this dichotomous key, identify the insect labeled "D"

• Ladybug

• Firefly

• Dragonfly

• Bee

Let's identify organism #4 together.

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Following the Key Practice

• ​It has NO backbone, so I'm going to look at b. I'll go to 5.

• It has NO antenna so I'm going to look at b.

• Organism #4 is a spider!

Multiple Choice

Using this dichotomous key identify organism 2.

• Snake

• Tortoise

• Lizard

• Ant

Looking at organism #2, this is how we can properly identify the lizard.
It has a backbone, it has no wings, it has legs, and it has no shell.
Therefore, it is a lizard!

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Reviewing the Key

You can see in this dichotomous key that there are no living things present. Instead, there's different types of rocks!

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​Dichotomous for non-living

Using this dichotomous key let's try to identify sample D:

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​Dichotomous for non-living

1. ​The rock is black - go to step 2.

2. The rock has a glassy texture

3. The rock is obsidian!

Multiple Choice

Using this dichotomous key, identify sample C:

• Conglomerate

• Granite

• Slate

• Gneiss

Multiple Choice

Using this dichotomous key, identify sample E:

• Conglomerate

• Granite

• Slate

• Gneiss