Characteristics of Life What does it mean to

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