Our Environment Test - 6

Substances that can be broken down by biological processes are said to be biodegradable. Substances like paper, wood and cloth are biodegradable.

The Montreal Protocol became effective in 1989. The Montreal Protocol is a protocol to the Vienna Convention for the Protection of the Ozone Layer. It is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion.

Ozone layer shields the surface of the earth from ultraviolet (UV) radiation from the Sun. Ozone depletion has resulted in more UV radiations on earth.

Organisms can be grouped as producers, consumers and decomposers according to the manner in which they obtain their sustenance from the environment. Micro-organisms belong to the group of decomposers. They break-down the dead remains and waste products of organisms.

Different materials in an ecosystem are cycled in separate biogeochemical cycles. Essential nutrients like nitrogen, carbon, oxygen and water are changed from one form to another in these biogeochemical cycles. Producers in an ecosystem fix up the solar energy and make it available for the next trophic levels.

The driving force of an ecosystem is solar energy. A food chain in an ecosystem always starts with photosynthesis. The autotrophs or the producers are at the first trophic level. They fix up the solar energy and make it available for heterotrophs or the consumers.

A food chain in an ecosystem always starts with photosynthesis. The autotrophs or the producers are at the first trophic level. They fix up the solar energy and make it available for heterotrophs or the consumers.

According to 10% law, the energy available to each successive trophic level is 10% of the previous trophic level. An average of 10% of the food eaten by a consumer is turned into its own body and made available for the next level of consumers. 10% can be taken as the average value for the amount of organic matter that is present at each step and reaches the next level of consumers.

An ecosystem consists of biotic components comprising living organisms and abiotic components comprising physical factors like temperature, rainfall, wind, soil and minerals.

The decomposers in an ecosystem are microorganisms, comprising bacteria and fungi. They break down the complex organic substances (dead remains and waste products of organisms) into simple inorganic substances, which go into the soil and are used up once more by the plants.