*Physical components* - These are non-living parts of the ecosystem which include sunlight, soll and air. Sunlight - used to make food during photosynthesis. It is the ultimate source of energy in the ecosystem. Soil - it provides plants with nutrients and water so that they grow well. Soil is a habitat for some organisms like ants and worms. Air - it is essential in an ecosystem. Components of air include: Carbon-dioxide - for photosynthesis needed by plants Note: carbon-dioxide is a by-product of respiration. Oxygen - living organisms need oxygen for respiration Note: oxygen is a by-product of photosynthesis Nitrogen - for plants and animals to make proteins, nitrogen must be present. However, plants and animals cannot absorb nitrogen gas directly from the environment therefore the nitrogen is converted by bacteria and fungi. Water vapour - the amount of water vapour in the air varies. Living organisms need water to survive in the ecosystem. Plants also need water to make food for the ecosystem.