2. Living Systems

3. Chapter Three: Classifying Living Things 3.1 Types of Living Things 3.2 Dichotomous Keys

4. A dichotomous key is a tool that helps its user identify natural objects like birds, trees, rocks, fungi, and insects. Dichotomous means "divided into two parts.”

5. 3.2 What is it? The ghost plant (Monotropa uniflora) lacks the green pigment chlorophyll, which gives most plants their color. How should we classify this species?

6. 3.2 Dichotomous Keys It is difficult to create a key for the kingdoms because there are so many organisms to consider.

7. 3.2 Dichotomous Keys A dichotomous key turns questions into paired statements.

8. 3.2 Dichotomous Keys Most dichotomous keys are designed to identify small groups like trees, butterflies, and song birds. Can you suggest a way to tell these arthropod classes apart?

9. 3.2 Dichotomous Keys Here is one solution…

10. Ecology Connection There are still remote regions on Earth, even though it may seem like humans have been everywhere. Discovering a New Species

11. Activity Scientists who study the characteristics of organisms and their relationships to other organisms are called taxonomists. Make a dichotomous key to identify your classmates’ shoes. Making a Dichotomous Key