1 / 14

Using Dichotomous Keys

Using Dichotomous Keys. Turner College & Career High School  2016. How is life organized ?. Life is organized at all levels from cells to biosphere All Organisms and systems are organized from simple parts into complex systems that must maintain homeostasis in order to survive.

thomasclarence
Download Presentation

Using Dichotomous Keys

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Using Dichotomous Keys Turner College & Career High School  2016

  2. How is life organized? • Life is organized at all levels from cells to biosphere • All Organisms and systems are organized from simple parts into complex systems that must maintain homeostasis in order to survive.

  3. But what if we find things we don't know and we want to know what they are? • We use something’s characteristics in a similar way using… What’s my name !?

  4. 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 twoparts. • Dichotomous keys always give two distinct choices in each step, often they are opposites. • Black/white; good/evil; pointed/rounded

  5. How to use a Dichotomous Key? Here are creatures we don’t know! Lets choose one

  6. How to use a Dichotomous Key? Choose only one creature at a time.

  7. How to use a Dichotomous Key? • Read steps 1a and 1b 1a. The creature has two eyes. Go to step 2. 1b.The creature has one eye. Go to step 5. • Decide which statement is true. • Statement 1b is true. • Go to Step 5, skipping steps 2-4.

  8. How to use a Dichotomous Key? • At 5, you make another dichotomous choice. • Read steps 5a and 5b 5a. The creature has 1 or more antennae. Go to step 6. 5b. The creature has no antennae.Its name is A. • Decide which statement is true. • Statement 5a is true. • Go to Step 6.

  9. How to use a Dichotomous Key? Keep going until you come to a step that gives you the creature’s name. • Read steps 6a and 6b 6a. The creature has 1 antennae. Go to step 7. 6b. The creature has 2 antennae. Its name is C. • Decide which statement is true. • Statement 6b is true.

  10. 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. • Then find all the creature’s names. C

  11. What if I need to Make a Dichotomous Key: • Use constant characteristics rather than variable ones. (Flowers change with the seasons) • Use measurements rather than terms like "large" and "small". • Make the choice a positive one • Something "is" instead of "is not". • Ex: snake ears are internal only • If possible, start both choices of a pair with the same word or item. • The body is “round” vs the body is “square” • Finish the dichotomous key with a full description of the organism.

  12. Dichotomous Keys

  13. NOW…

More Related