In an ecosystem, decomposers convert :
Important Points to Remember in Chapter -1 - Our Environment from S.P. Sharma ESSENTIALS OF BIOLOGY CLASS X Solutions
(i) The solid waste we generate may be biodegradable or non-biodegradable.
(ii) Substances that can be broken down by biological process are called biodegradable; the substances that are not broken down in this manner are called non-biodegradable substances.
(iii) Many human-made materials like plastics will not be broken down by the enzymatic action of microbes. So, these non-biodegradable substances persist for a long time.
(iv) Domestic waste products, sewage, agricultural residue, paper, and cloth are biodegradable, but plastics, polythene bags, and aluminum foil are non-biodegradable substances.
(v)Our environment is composed of biotic and abiotic components.
(vi) The various components of an ecosystem are interdependent.
(vii) All the interacting organisms in an area, together with the non-living constituents of the environment, form an ecosystem.
(viii) Organisms can be grouped as producers, consumers, and decomposers. All green plants and certain blue-green algae which can produce food by photosynthesis come under producers.
(ix) The organisms which consume the food produced, either directly from producers or indirectly by feeding on other consumers, are the consumers. Consumers can be grouped as herbivores, carnivores, omnivores.
2. Food chain and food web:
(i) A series of organisms feeding on one another constitute a food chain. Each step of the food chain forms a trophic level.
(ii) When a number of food chains are interlinked together, it is called a food web. It provides stability to the food chain.
(iii) The flow of energy is unidirectional.
(iv) Only of energy is transferred from one trophic level to the next successive trophic level while the rest of the energy is lost during the transfer of energy and during respiration. This is known as the law of energy transfer.
(v) Several pesticides and other harmful chemicals enter the food chain. The toxin concentration increases successively in the organism's tissues across the food chain. This phenomenon is known as biological magnification.
(vi) Due to biological magnification, wheat, rices, vegetables, fruits, and even meats contain varying amounts of pesticide residue.
3. Ozone layer and its depletion:
(i) Ozone shields the Earth's surface from UV radiation from the sun. This radiation is highly damaging to organisms by causing skin cancer in human beings.
(ii) The amount of ozone in the atmosphere began to drop sharply in the . This decrease has been linked to synthetic chemicals like CFCs (chlorofluorocarbons) used as refrigerants and in fire extinguishers.
(iii) In, the United Nations Environment Programme (UNEP) succeeded in forging an agreement to freeze CFC production.
