Unicellular vs. Multicellular.pdf

Unicellular vs. Multicellular Organisms What is an “organism”? Organism: An organism is something that is living. Cells: A cell is the smallest unit of life that is classified as a living thing. http://vimeo.com/37107992 Do all living things have the same amount of cells? Structure Unicellular Organ...

Unicellular vs. Multicellular Organisms What is an “organism”? Organism: An organism is something that is living. Cells: A cell is the smallest unit of life that is classified as a living thing. http://vimeo.com/37107992 Do all living things have the same amount of cells? Structure Unicellular Organism Body is made up of a single cell Multicellular Organism Body is made up of numerous cells All organisms perform the following LIFE FUNCTIONS: 1. 2. 3. 4. 5. 6. growth movement reproduction (make more of themselves) respiration (breathing/gas exchange) nutrition (finding food for energy) excretion (getting rid of wastes) Specialization Unicellular Organism A single cell carries out all the life processes Multicellular Organism Different cells are specialized to perform different functions Exposure to Environment Unicellular Organism The cell is exposed to the external environment on all sides Multicellular Organism Only outer cells are specialized to face the environment. Inner cells are devoted to other functions Injury Unicellular Organism An injury of the cells can cause death of the organism Multicellular Organism Injury or death of some cells does not affect the organisms as the same can be replaced by new one Size Limitation Unicellular Organism A cell body cannot attain a large size because of the limit imposed by surface area to volume ratio Multicellular Organism A multicellular body can attain a large size by increasing the number of small cells Lifespan Unicellular Organism Lifespan is short due to heavy load of work Multicellular Organism Lifespan is long due to limited load of work for each cell type Regeneration Unicellular Organism A well-marked capacity of regeneration is present Multicellular Organism The capacity of regeneration decreases with increasing specialization (more special = less easy to regenerate)