Studying Life: What does it mean to be alive? Objectives: 1. Describe some characteristics of living things 2. Explain how life can be studied at different levels Question: 1. What does it mean to be alive? 2. What do all living things have in common? 3. Are there any non-living objects that have living characteristics? Is this fire alive???

1. Cells All living things are made up of cells Cells are the smallest units of an organism that can be considered alive Cells can grow, respond, and reproduce Despite their small size, they are complex and highly organized Unicellular organisms = 1 cell Multicellular = many cells Stem Cells

2. Reproduction All living things produce other living things There are 2 types of reproduction =Sexual: cells from 2 different parents unite to form first cell =Asexual: New organism as a single parent

3. Based on a Genetic Code Offspring resemble their parents Asexual reproduction results in offspring with identical traits Sexual reproduction creates variety with similar features DNA: carries directions for inheritance

4. Growth and Development All living things grow at some point in their lives For many single-celled organisms growth is simply an increase in size For multi-cellular organisms they develop from one cell into many through cell division As the cells develop they take on different rolls Nerve CellSkin Cells Blood Cells

5. Materials and Energy Organisms need materials and energy to stay alive Metabolism: process of breaking down materials for energy that is needed to make other vital materials Autotrophs: use sunlight as their source of energy Heterotrophs: consume other organisms for energy Autotroph or Heterotroph?

6. Response to Environment Organisms detect and respond to stimuli in the environment

7. Maintain Internal Balance Homeostasis: process of maintaining a stable internal environment (Temperature)

8. Evolution Change of a species over time Individuals do not evolve Groups of organisms can change