How do living things take in air, food and water?
That depends entirely on the type of organism you are talking about: Land-plants take in their water through their roots, and their gas requirements by diffusion from the air; and their “food” is sunlight, water, and CO2 (which they use to manufacture sugars by photosynthesis). Animals might have lungs or gills to breathe, or they might have spiracles or other gas-exchange mechanisms for their oxygen requirements. They eat other organisms for their food, and they drink water (or take it in by diffusion across their gills if they are aquatic). Multicellular fungi mostly consist of a meshwork of fine fibres called hyphae. These take in oxygen and water by diffusion, and they extract their food from their immediate environment by secreting digestive enzymes, and then absorbing the released nutrients.
