Our Environment

An ecosystem is all the living things (biotic) plus their non-living surroundings (abiotic — air, water, soil, light) interacting together. The living members play three roles:

• Producers — green plants that make food by photosynthesis.
• Consumers — herbivores, carnivores and omnivores.
• Decomposers — bacteria and fungi that break down dead matter and recycle nutrients.

A food chain shows who eats whom, level by level (trophic levels). Energy flows one way and only about 10% passes to the next level — the rest is lost as heat. That is why chains rarely have more than 3–4 levels. See it:

Some harmful chemicals (like the pesticide DDT) are not broken down or excreted. As one organism eats many of the level below, these toxins become more concentrated at each higher trophic level — this is biological magnification. The top carnivores (and humans) end up with the highest, most dangerous levels.

Ozone (O₃) high in the atmosphere absorbs the Sun's harmful ultraviolet (UV) rays, protecting us from skin cancer and crop damage. CFCs (chlorofluorocarbons, from old refrigerants and sprays) break ozone apart, thinning the layer. Global agreements now phase CFCs out.

Biodegradable wastes are broken down by microbes; non-biodegradable wastes (plastic, glass, metals) persist and pollute. Sorting them is the first step to reduce, reuse, recycle. Tap a category: