What is Life?

Characteristics of Life

• Cellular Organization: All living things are composed of one or more cells.
• Growth and Development: Living organisms grow and undergo changes in form and function over their lifetime.
• Reproduction: Living organisms can reproduce and create offspring.
• Response to Stimuli: Organisms respond to their environment and can detect and respond to changes in their surroundings.
• Homeostasis: Living organisms maintain a stable internal environment despite external changes.
• Heredity: Living organisms pass on genetic information to their offspring.
• Adaptation: Living organisms can adapt to their environment through the process of natural selection.

Domains of Life

1. Archaea: Single-celled microorganisms that are similar to bacteria but have different evolutionary histories.
2. Bacteria: Single-celled microorganisms that can be found in various environments.
3. Eukarya: Organisms with complex cells, including plants, animals, fungi, and protists.

Life Processes

1. Metabolism: The chemical processes that occur within a living organism to maintain life.
2. Respiration: The process of obtaining energy from the intake of oxygen and release of carbon dioxide.
3. Photosynthesis: The process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll.
4. Excretion: The process of eliminating waste products from the body.
5. Nutrition: The process by which organisms obtain and use food for growth, maintenance, and repair.

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