Q1. Name any two biodegerable pollutants. Ans – Sewage and paper Q2. List any two non-biodegradable pollutants. Ans – DDT, mercury Q3. List four common waste disposal methods. Ans – Landfills, recycling of wastes, preparation of compost, and incineration Q. What is incineration ? Ans – Incineration is the process of burning of huge waste at high temperature ( usually more than 1000 C ) converting into gases , water vapours , and ash is left behind. It is used to dispose of household waste , chemical waste , and hospital waste. Q. Name the three major biotic components of an ecosystem. Ans – Plants , animals , and micro-organisms. Q. Name the decomposers ? Ans – Bacteria , fungi of decay. Q. Which are more numerous , secondary consumers or tertiary consumers ? Ans – Secondary consumers Q. What is the ultimate source of energy for organisms ? Ans – Sunlight Q. Name the radiations that are absorbed by ozone blanket. Ans – ? Ultraviolet ( UV ) radiations Q. In which year did UNEP succeed in forging an agreement between nations to freeze CFCs concentration to 1986 level ? Ans – 1987 Q. In an ecosystem , insects feed on plant matter. Name the trophic level to which the insects belong ? Ans – Herbivore level ( primary consumer level ). Q Define food chain ? Ans – Food chain is the sequential interlinking of organisms involving the transfer of food energy from the prodecers , through a series of organisms with repeated eating and being eaten is called food chain. Q. What is food web ? Ans – Food web is a network of food chains which become interconnected at various trophic level so as to form a number of feeding connections amongst different organisms in a biotic community. Q. Name two basic components of an ecosystem . Ans – (i) Abiotic component , and (ii) biotic component Q. Give reason why ozone layer in the stratosphere is considered useful ? Ans – Ozone layer in the stratosphere protects the living organisms including man from UV radiations of the sun by absorbing most of them. Q. Why plastic bags and containers should not be disposed of by burning ? Give reason. Ans – It is so because plastic , when burnt , gives off noxious fumes which pollute the air. Q. Give examples of autotrophs in a garden ecosystem. Ans – Grasses , flower plants and trees Q. Give examples of heterotrophs in an ecosystem. Ans – All animals and decomposers are heterotrophs Q. Which of the following are essential components ? (i) primary consumers , (ii) secondary consumers , (iii) decomposers Ans – Decomposers Q. Define autotrophs. Ans – Autotrophs are the organisms which can synthesize their own food from simple inorganic sustances by utilising solar energy or other form of energy , e.g. green plants. Define heterotrophs. Ans – Heterotrophs are the organisms which can not synthesize their own food and hence depend on plants directly or indirectly , e.g. , all animals Q. Give names of chemicals which are responsible fror thinning of ozone layer. Ans – Chlorofluorocarbons ( CFCs ) , methane ( CH4 ) , and oxides of nitogen ( NOX ). Q. Expand UNEP. Ans – UNEP stands for United Nations Environment Programme. Q. What kind of cups are being used now a days in trains for serving tea / coffee / soup etc. in our country ? Ans – Disposable paper cups Q. Expand the term ODS. Ans – ODS stand for Ozone Depleting Substances Q. Which two gases have replaced Chlorofluorocarbons ( CFCs ) ? Ans – Hydrofluorocarbon ( HFC ) , and Hydrochlorofluorocarbon ( HCIFC ). Q. From the following list , pick out the items which can be recycled : Pestisides , polythene carry bags , newspaper , used clothes , glass bottles Ans – Polythene carry bags and newspaper can be recycled. Q. what are the biological components of environmrnt ? Ans – Plants and animals Q. What do you call the functional unit of the environment comprising both living and non-living components ? Ans – Ecosystem Q. Which two of the following are biodegradable ? Tomato leaves , Aluminium wire , synthetic fibre , wool Ans – Tomato leaves and wool Q. Which of the following are not biodegradable ? Wool , glass , silver foil , leather Ans – Glass and silver foil Q. Why is it necessary to conserve our environment ? Ans – It is necessary to conserve our environment to have ecological balance. Q. Which of the following gases is the major constituent of biogas ? Ans – Methane gas ( about 75% ) is the major constituent of biogas. Q. Why are green plants called producers ? Ans – Green plants are called producers because they utilise solar energy to convert raw materials into organic compounds ( carbohydrates ) by the process called photosynthesis. Q. What is a green house ? Green house is a building made chiefly of glass for growing or sheltering the delicate or exotic plant species is called a green house. Q. What is green house effect ? Ans – ……………..