Multicellular Organization

I. Tissues, Organs, & Organ Systems a)Cells are organized into tissues (a group of cells that carry out a specific function)

b) Types of tissues: epithelial, connective, muscle, nerve.

c) An organ is formed when several types of tissue interact to perform a specific function Ex: stomach (muscle, epithelial, connective, and nerve tissue)

D. An organ system is composed of a group of organs that perform a set of related tasks. Ex: the digestive system (mouth, esophagus, stomach, intestines) E. Types of plant tissue: dermal, ground, vascular. F. Types of plant organs: roots, stems, leaves, and flowers.

II. Evolution of Multi-Cellular Organization Fossil records indicate the earliest cells were simple prokaryotes like present day bacteria. Fossil records indicate the earliest cells were simple prokaryotes like present day bacteria. Organisms dependent on limited organic resources reproduced competition of resources cells with adaptations evolved (early eukaryotes) Organisms dependent on limited organic resources reproduced competition of resources cells with adaptations evolved (early eukaryotes)

1. Definition: A collection of genetically identical cells that live together in a closely connected group. 2. Example: green alga Volvox a. Outer cells use flagella for movement b. Cells involved with reproduction A. Colonial Organizations

3. Unicellular organisms Colonial organismsTrue multicellular organisms 4. Some believe that plants, animals, and fungi evolved from different colonial organisms hundreds of millions of years ago.