1. Living organisms: This includes all plants, animals, fungi, bacteria, and other microorganisms. They all interact with each other and their environment.

2. Physical environment: This includes the Earth's atmosphere, hydrosphere (water), and lithosphere (land). These provide the conditions necessary for life, such as air, water, and nutrients.

3. Chemical interactions: These include the flow of energy and matter between living organisms and their environment. For example, photosynthesis converts sunlight into energy, and respiration releases carbon dioxide into the atmosphere.

These three components work together to create a complex and interconnected system that sustains life on Earth.