1. Introduction to Living Things
Table of Contents
What Is Life?
Classifying Life
Domains and Kingdoms
Evolution and Classification

2. What Is Life? Redi’s Experiment
Francesco Redi designed one of the first controlled experiments. Redi showed that flies
do not spontaneously arise from decaying meat.

3. What Is Life? Pasteur’s Experiment
Louis Pasteur’s carefully controlled experiment demonstrated that bacteria arise only from existing bacteria.

4. Classifying Life Aristotle and Classification
Aristotle, an ancient Greek scholar, developed a classification system for animals.

5. Classifying Life Levels of Classification
Domain Eukarya
Kingdom Animalia
Levels of Classification
The number of organisms on each level decreases as the levels of classification get lower and the organisms share more characteristics with each other, and are related.
Phylum Chordata
Class Aves
Order Strigiformes
Family Strigidae
Genus Bubo
Species Bubo
virginianus

6. Classifying Life Identifying Organisms
The six paired statements in this taxonomic key describe physical characteristics of different organisms.

7. Domains and Kingdoms The table shows the number of species of bees,
mammals, and birds that scientists have found so far!

8. Domains and Kingdoms Three Domains of Life
Bacteria and Archaea are unicellular organisms that have no nucleus. Organisms with cells that contain nuclei are called Eukarya.

9. Evolution and Classification
A Branching Tree
This branching tree diagram shows how cats have evolved.

10. Evolution and Classification
Note the characteristics of Figures A, B, C, and D. Which Figure is most like Figure B? If these figures represent fossils of extinct organisms, which would be the ancestor of the others?

11. Evolution and Classification
Convergent Evolution
Birds and insects both use wings to fly, but they are not closely related organisms.