An ecosystem is a community of organisms interacting with their physical surroundings. Producers make food, consumers eat it, and decomposers return nutrients to the soil, keeping the cycle going.
Greenhouse gases such as carbon dioxide and methane trap heat and drive global warming. Ozone in the stratosphere shields the earth from ultraviolet radiation, and chlorofluorocarbons damage it.
Conservation appears in exams through protected areas, national parks and international days. India's Project Tiger is a standard example of species-focused conservation.