The role of living things

 The living and nonliving things in any area form a community are called ecosystem. They act on one another in many ways. Two of the most important ways are through food chains and chemical cycles.

Life could not exist without energy from the sun. The sun's energy travels to earth as light. It affects plants and animals through chemical processes. All plants and animals are linked together in these processes. The sun's energy flows through all of them in a continuing path called a food chain.

Plants-eating animals, or herbivores, consume (eat) the plants. In their own bodies, these animals reorganize the chemical in the plants and use them as nourishment. The same thing happens when a plant-eating animal, such as rabbit, is eaten by a meat-eating animal, or carnivore, such as a fox. (animals that eat both plants and meat are called omnivore).

A certain process takes place when living things die. Bacteria" and fungi break the chemical compounds down into simple nutrients. This process is called decomposition. The nutrients from decaying animals enter the soil, where they are used again by plants.

Thousand of years ago, the human population was much smaller than it is today and people did not greatly affect the balance of nature. Several hundred people who lived as community of hunters did not kill enough animals to disturb the balance of their ecosystem. A few thousand people who lived by a river, and discarded waste did not pollute the water enough to change the ecosystem.

Today the human population is enormous; And people have created many ecological crises, especially in areas where the population has grown quickly. Their demand for space, their production of waste, and their need for quantities of food, water, and energy all have had an important effect on natural system. Very often, the activities of people have upset the natural balance.

Posted in: Article