4.3 Multicellular Organization  Unicellular  One cell carries out everything.  Multicellular *Cells are differentiated to perform specific functions.

Cells make up Tissues that make up Organs that make up Organ Systems that make up Complete Organisms.

Cells  The basic unit of life.

Tissues  A group of similar cells which carry out a common function.

Organ  Several types of body tissues that together form a function. Examples are stomach, lungs, heart.

Organ System  A group of organs that interact to perform a set of related tasks. Examples of organ systems are; digestive, respiratory, reproductive, endocrine, immune, urinary.

Organ System  The digestive system is made up of the following organs: mouth, esophagus, stomach, large intestines, small intestines, pancreas, gall bladder.

Organism  Living things.

Specialized Tissues (“MENC”)  Muscle *contraction  Epithelial *surface covering  Nervous *transmits messages  Connective *support and link together

Specialized Tissues  Example of specialized tissues.  Take cells that make up the stomach. *muscle tissue causes movement. *epithelial tissue secretes enzymes. *nervous tissue transmits messages back and forth from stomach to brain. *connective tissue holds stomach together.

Plants have Tissues and Organs  Vascular tissue transports water and nutrients from leaves to roots and from roots to leaves.  Organs are roots, stems, leaves.

Prokaryotes *First cells on Earth. * Evidenced by fossils  Did not produce own food.  Depend on nutrients in environment. *Through evolution, these cells started to compete for the environment and cells with adaptations evolved. These were eukaryotes.

Colonial Organisms  A collection of genetically identical cells that live together in a closely connected group and each cell group has its own function.  The green alga known as volvox is the evolutionary link between unicellular organisms and multicellular organisms. It still lacks tissues and organs.