How do we define life?

How do we define life?

Properties of Living Things

• Are organized, and are made of one or more cells (Cellular Organization)

• Maintain stable internal conditions (Homeostasis)

•Are capable of Reproduction

•Exhibit Growth and development

•Respond to their environment(Responsiveness)

Properties of living things (continued)

• Pass traits to offspring (Heredity)

• Use energy. Metabolism is the sum of all chemical reactions carried out in an organism.

Stimulus or response?• The bell rings at the end of a class period• Your dog runs into the kitchen when you

open a can• A paramecium backs up and moves away

when it encounters an obstacle. • A plant grows toward the window• A baby hears a loud noise• You pull your hand away after touching the

hot oven

Examples

• Hummingbirds feed almost constantly to supply energy to their racing wings and hearts.

• Metabolism, homeostasis

• A butterfly emerges from a cocoon.

• Growth and Development

A bacterium divides into new cells every 15 minutes

• Reproduction

•  An elephant's large ears allow the blood in the ears to be cooled by as much as 10 degrees.

• Homeostasis, responsiveness

• A pill bug rolls into a ball when touched.

• Responsiveness

• Earthworms are made of specialized cells, such as digestive cells, muscle cells, skin cells, etc.

• Cellular Organization

•A female frog lays many eggs at a time

• Reproduction

• A toad burrows in the mud during hot weather to avoid water loss

• Homeostasis

• Responsiveness

•An amoeba is composed of a single cell

•Cellular Organization

A child inherits cystic fibrosis from her parents

• Heredity

Mitochondria in a cell release energy from sugars

• Metabolism, cellular organization, homeostasis

Branches of Biology• Biochemistry: chemistry of

life

• Ecology: how organisms interact with each other and their environment

• Cell biology: life on the cellular level

• Genetics: how organisms pass traits to their offspring

• Evolution: changes in organisms over time

• Microbiology: microscopic organisms

• Botany: plants

• Zoology: animals