Characteristics of Life Chapter 9: Lessons 1

What makes YOU “living”? All living things have ALL the characteristics of life. Things that have all the characteristics of life are called ORGANISMS. Characteristics of Life: 1.organization 2.growth & development 3.reproduction 4.response to environment 5.maintaining internal conditions 6.use of energy

Organization Whether a living thing is made up of only one cell or many, all are ORGANIZED. Cell – smallest unit of life Organisms can be unicellular – made up of one cell multicellular – made up of many cells Unicellular organisms have structures in the cell with special functions (like a house with rooms) Multicellular organisms have specific groups of cells with specialized functions (like digestion or breathing)

Growth & Development Growth means to increase in size In unicellular organisms, growth happens when the cell grows in size In multicellular organisms, growth is when the number of cells increases Development are changes that happen to an organism in its lifetime

Reproduction Once organisms grow and development, they can be able to reproduce. Reproduction – the process of when an organisms makes one or more new organisms IMPORTANT for living things to continue existing Unicellular organisms reproduce by diving (splitting in two) Some organisms need a mate to reproduce, but others can reproduce without a mate. Number of offspring can vary. (frog produces hundreds; humans produce just one or two)

Response to Stimuli All living things respond and react to changes (stimuli) Changes can occur inside an organisms body or on the outside (in their environment) Internal stimuli happen inside (example: hunger, thirst) External stimuli happen in the environment (example: sweating when temp. increases) Energy All living things need and use energy Everything you do requires energy in order to happen Digestion Breathing Sleeping Thinking Cells use energy ALL energy originates from the SUN

Homeostasis All living things MUST maintain a stable internal environment; if not you are no longer living (DEAD). Homeostasis – maintaining steady internal conditions when outside conditions change EXAMPLES: Using the restroom to urinate when you drink too much water is an example. Sweating when it is too hot to maintain your body temperature Shivering when it’s too cold to make your body warmer Organisms become sick or even die if they cannot maintain homeostasis