Characteristics of Living Things Chapter 1 Section 3

1. Living things are made up of units called cells. The cell is the smallest unit of an organism that can be considered alive.

2. Living things reproduce. This means they can produce new organisms, either by sexual or asexual reproduction.

3. Living things are based on a universal genetic code. Organisms store the information they need to live, grow, and reproduce in a genetic code stored in the molecule known as DNA.

4. Living things grow and develop. Organisms have particular patterns of growth and development. Cells can divide and differentiate, which means they start to look different from one another and perform different functions.

5. Living things obtain and use materials and energy. Organisms must take in materials and energy to grow, develop, and reproduce. Metabolism is the process of chemical reactions that organisms use to build up or break down materials.

6. Living things respond to their environment. Organisms can detect and respond to stimuli in their environment. A stimulus is any signal an organism responds to.

7. Living things maintain a stable internal environment. Even when conditions outside an organism change dramatically, most organisms must maintain constant conditions within their bodies. This process is known as homeostasis.

8. Taken as a group, living things change over time. Change over time is referred to as evolution. The basic traits an organism inherits from its parents usually do not change. Over many generations, however, given groups of organisms change over time.