Characteristics of Living Characteristics of Living ThingsThings

How do you know if something is How do you know if something is alive?alive?

• All living things…– Are made up of units called cells– Reproduce– Are based on a universal genetic code– Grow and develop– Obtain and use materials and energy– Respond to the environment– Maintain a stable internal environment– As a group, living things change over time

What is a cell?What is a cell?

• A collection of living matter enclosed by a barrier that separates the cell from its surrounding.

• Cells are the smallest units of an organism that can be considered alive.

• Unicellular = one cell

• Multi-cellular = many cells

ReproductionReproduction

• Producing new organisms

• Sexual reproduction= cells from 2 different parents unite to produce the first cell of the new organism.

• Asexual reproduction= the new organism has a single parent

Based on a Genetic codeBased on a Genetic code

• Offspring resemble their parents because they inherited traits from their parents.

• The directions for inheritance are carried on DNA.

• This genetic code determines the inherited traits of every organism on earth.

Growth and DevelopmentGrowth and Development

• All organisms grow during at least part of their lives

• Single celled organisms simply grow in size

• Multi-cellular organisms grow by development.

Need for materials and energyNeed for materials and energy

• Organisms use energy and materials to grow and stay alive

• Metabolism = the combination of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes

Response to the environmentResponse to the environment

• Organisms detect and respond to stimuli from their environment.

• Stimulus = a signal to which an organism responds

Maintaining internal balanceMaintaining internal balance

• Even though conditions in the external environment vary, most organism must keep internal conditions fairly constant to survive

• Homeostasis = maintaining internal stability.

EvolutionEvolution

• A group of organisms will change over time

• As the environment changes a group of organism will change to adapt through the passing of traits from one generation to the next generation