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...P a g e science class notes for our environment introduction the includes physical surroundings like air or atmosphere water bodies soil land and all organisms such as plants animals human beings micro bacteria fungi called decomposers waste materials produced by various activities of man are poisonous to some extent can be divided into two main groups biodegradable wastes non ecosystem an is self contained unit living things their forest pond lake greenland etc there components biotic component abiotic it three types producer consumer decomposer saprophyte consumers further herbivores carnivores omnivores planktons very minute microscopic freely floating on surface in river ocean phytoplanktons zooplanktons aquatic protozoa example zooplankton which break down complex organic compounds present dead products faeces urine simpler substances food chains webs sequence community one organism consumes another transfer energy chain unidirection where takes place only direction www ncerthelp ...