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

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.

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

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

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

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

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

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.

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

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?

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