Transcript PowerPoint Dichotomous Key

Dichotomous
Key
Using Observable Characteristics
to Identify Objects
Dichotomous Keys
 A dichotomous key is a tool that allows the
user to determine the identity of items in
the natural world based on the items
characteristics
 "Dichotomous" means
“divided into two parts” Greek origin
 dichotomous keys always give two distinct
choices in each step, often they are opposites
Black/white; good/evil; pointed/rounded
Dichotomous key
Example of a dichotomous key…
1 With flower.
Without flower
2 Seedless.
Seed bearing
3 Plant body do not differentiated into root,
stem and leaves.
Plant body differentiated into root, stem and
leaves
4 Without photosynthetic pigment.
With chlorophyll or other photosynthetic
pigment
5 No vascular tissues.
With vascular tissues
Angiosperms
Go to 2
Go to 3
Gymnosperms
Go to 4
Go to 5
Algae
Fungi
Mosses
Fern
Dichotomous key
 the dichotomous key can also be expressed in a diagram form
Plants
With flower
Without flower
Flowering Plants
(Angiosperm)
Non-flowering plants
Seed-bearing
Seedless
Plant body not
differentiated into
root, stem and
leaves
Without photsynthetic pigment
Algae
Plant body
differentiated
into stem and
leaves
With chlorophyll or
other photosynthetic
pigment
Fungi
No vascular
tissues
With vascular
tissues
Mosses
Ferns
Gymnosperms
How to use a Dichotomous Key?
Here are creatures we don’t know!
Lets choose one
How to use a Dichotomous Key?
Choose only one creature at a time.
How to use a Dichotomous Key?
Read steps 1a and 1b
Decide which statement is true
1b is true
How to use a Dichotomous Key?
Then follow the directions after that step.
How to use a Dichotomous Key?
At choice 5, you make another dichotomous choice
5a is true
How to use a Dichotomous Key?
Keep going until you come to a step
that gives you the creature’s name.
6 a. The creature has one antennae
Go to Step 7.
How to use a Dichotomous Key?
Choose a new creature and start at step 1a and 1b
again. Continue until you find the creature’s name.
C
Where do you start Again?
Then, find the names of all the
creatures
1. a. wings covered by an exoskeleton – go to step 2
b. wings freely observed – Go to step 3
2. a. body has a round shape ……….ladybug, a red beetle with
black spots
b. body has an elongated shape ……….grasshopper, a green
insect that hops
3. a. wings point out from the side of the body ……….dragonfly,
an insect that is 10- 15 cm long and lives in marshes
b. wings point to the posterior of the body ……….housefly, a
flying insect with red eyes and an annoying buzz
Pick an individual to identify,
Use ayou
dichotomous
keystart.
to
When
are ready click
identify these individuals.
Start
Is the individual male or female?
Male
Female
Is the individual wearing a hat?
Hat
No Hat
Is the individual in the military?
Military
Not Military
Is he wearing a dress uniform or a
camouflage uniform?
Dress
Uniform
Camouflage
Uniform
Arnold
Introducing
He is a man
wearing a hat
and a military
dress uniform.
Return to Start
Hector
Introducing
He is a man
wearing a hat
and a camouflage
military uniform.
Return to Start
Greg
Introducing
He is a man
wearing a hat,
but not wearing a
military uniform.
Return to Start
Does the individual have facial
hair or is he clean shaven?
Facial
Hair
Clean
Shaven
Is the individual wearing black?
Wearing
Black
Not Wearing
Black
What is the individual wearing?
Suit
Jeans
Reggie
Introducing
He is a man with
facial hair,
wearing a black
suit, but not
wearing a hat.
Return to Start
Hugo
Introducing
He is a man with
facial hair, wearing
a black shirt and
jeans, but not
wearing a hat.
Return to Start
Bill
Introducing
He is a man with
facial hair who is
not wearing black
or a hat.
Return to Start
What is the individual wearing?
Shorts
Pants
Jack
Introducing
He is a clean
shaven man who
is wearing shorts,
but not black or a
hat.
Return to Start
Kurt
Introducing
He is a clean
shaven man who
is wearing pants,
but not black or a
hat.
Return to Start
Is the individual wearing a hat?
Hat
No Hat
Is the individual wearing purple?
Wearing
Purple
Not Wearing
Purple
What is the individual wearing
Green Boa
and Hat
Red Boa
and Hat
Doris
Introducing
She is wearing a
purple dress and
green boa and
hat.
Return to Start
Does the individual have a purse?
Purse
No Purse
Introducing
Erin
She is wearing a
purple dress and
red purse, boa,
and hat.
Return to Start
Introducing
Rhonda
She is wearing a
purple dress and
red boa and hat.
Return to Start
Introducing
Gail
She is wearing a
hat, but not
wearing purple.
Return to Start
What is the individual wearing?
Pants
Skirt
Introducing
Jenny
She is wearing
pants, but not a
hat.
Return to Start
What color boots is the individual
wearing?
Red
Black
Introducing
Mary
She is wearing a
skirt and red
boots, but not a
hat.
Return to Start
Introducing
Beth
She is wearing a
skirt and black
boots, but not a
hat.
Return to Start
How to use a dichotomous key?
HA! HA!
Dichotomous
Keys