Characteristics of Life

What does it mean to be alive? All living things share common characteristics

Homeostasis Maintaining a steady, stable condition in the body Feedback mechanisms Negative feedback What happens when your systems need to slow down or completely stop a process Positive feedback What happens to cause a process to start or continue

Homeostasis example Body Temperature Humans are homoeothermic organisms, which means they regulate their own body temperature. If humans get too cold, a series of actions are taken to warm your body. The nervous system recognizes when the temperature drops and starts muscular system shivering. Shivering allows heat to be generated. Likewise, when humans get too warm, the nervous system starts up the sweating process.

Growth and Development All organisms grow and develop Instructions are coded for by their genes Cell division - the formation of new cells Cell enlargement - the increase in size of a cell. Cells grow to a certain size and then divide An organism gets larger as the number of its cells increases

Response to Environment Organisms respond to different stimuli Positive response Movement toward a stimulus Negative response Movement away from a stimulus

Response to Environment examples Plants can grow toward a source of light, climb on fences and walls, or respond to touch Bacteria move toward or away from chemicals or light

Adaptation Adaptations are traits giving an organism an advantage in a certain environment Physical Behavioral Evolution

Cellular Organization Organisms are made out of cells Unicellular Multicellular Cells are organized Tissue - a group of cells that perform a common function. Organ - a group of tissues that perform a common function. Organ system - a group of organs that perform a common function. Organism - any complete living thing.

Reproduction Reproduction must occur for a species to survive All living things reproduce in one of the following ways: Asexual reproduction - Producing offspring without the use of gametes (egg & sperm) Sexual reproduction - Producing offspring by the joining of gametes

Energy Use and Metabolism Organisms take in energy and use it for maintenance and growth Metabolism is the chemical process that transforms the energy