What is Life?

What is Biology? Biology is the study of living things. Bio = life Ology = study of

What are living things? Living things are called organisms. Organisms are made up of atoms organized into molecules. When molecules are organized together they form cells.

What are living things? Cells work together to form organs. Organs work together to form organ systems. Several organ systems together make up an organism.

Structure of Life

Structure of Life Molecular – consists of atoms and molecules. Building blocks of life. Cellular – Smallest unit of life capable of carrying out all functions of living things.

Structure of Life Tissue – Group of cells that work together and have similar functions. Organ – Group of tissues that work together and have the same function.

Structure of Life Organ system – Group of organs working together that have a similar function Organism – Group of organ systems that work together.

Structure of Life Population – Group of organisms of the same species living together in a location. Community – all populations of different kinds living together in an area.

Structure of Life Ecosystem – community of organisms in an area, as well as the non-living factors. Biosphere – The part of the earth that contains all ecosystems.

What is Living? Biotic – Living factor that shapes the ecosystem. Ex: Frog Abiotic – physical nonliving factor that shapes the ecosystem. Ex: Rock

Criteria for Life So how do we determine which objects are living and which are nonliving? There are 8 criteria an object must meet in order to be considered living.

1. Cells Every living thing is composed of one or more cells. Some cells are specialized for certain functions.

2. All living things Reproduce All living objects are capable of reproducing.

3. Genetic Code All living things are based on a genetic code. DNA provides instructions for making various molecules.

Genetic Code

4. Living Things Grow and Develop All organisms grow. In single-celled organisms, the cell gets bigger. In multi-cellular organisms, the number of cells increases.

5. Living things use energy Living things metabolize, which means they break down material to make energy.

6. Respond Living things interact with and respond to their environment.

7. Homeostasis Living things maintain a stable internal environment, which is called homeostasis.

8. Change over time All living things change over time and adapt to their environment.