The Characteristics of Life Life is diverse yet all living things share common characteristics. Living things are organized.

Living things acquire materials and energy. Photosynthetic organisms use carbon dioxide, water, and solar energy to make food. Animals obtain nutrients and energy from food eaten. Energy is the capacity to do work. Many living things can convert energy to motion.

Living things reproduce. Genes (DNA) contain information needed for heredity and metabolism. Metabolism is all the chemical reactions in the cell. Reproduction may be asexual or sexual.

Living things respond to stimuli. Living things may respond to external stimuli by movement toward or away from a stimulus. Movement constitutes part of the behavior of an organism. Movement in animals is possible because of muscular and skeletal systems.

Living things are homeostatic. Homeostasis is the ability of an organism to maintain relatively constant internal conditions. An example is temperature regulation in the human body. All organ systems contribute to homeostasis.

Living things grow and develop. All organisms undergo development. Growth, with increases in size and number of cells, is part of development. Development involves many stages from conception until death.

Review Guide for Quiz 9/11/09 Characteristics of Life 1. Energy- Living things acquire materials and energy. Photosynthetic organisms use carbon dioxide, water, and solar energy to make food. Animals obtain nutrients and energy from food eaten. Energy is the capacity to do work. Many living things can convert energy to motion. 2. Growth- Living things grow and develop. 3. Reproduce- Living things reproduce. Reproduction may be asexual or sexual. 4. Respond to Stimuli - Living things may respond to external stimuli by movement toward or away from a stimulus. A stimulus is a change (external or internal) in the environment of an organism that initiates a response. 5. Homeostasis- Homeostasis is the ability of an organism to maintain relatively constant internal conditions. An example is temperature regulation in the human body. All organ systems contribute to homeostasis.