CBSE Class 12 (Science) Ecosystem — practice questions
80 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice CBSE Class 12 (Science) Ecosystem in the app →Which of these is a terrestrial ecosystem?Which is a man-made ecosystem?The basic energy input to any ecosystem is:Green plants in an ecosystem are called:Animals that feed directly on plants are:Producers belong to which trophic level?Energy movement through trophic levels is:The rate of biomass production is called:GPP minus respiration losses equals:The rate at which consumers form new organic matter is:The annual net primary productivity of the biosphere is about:Raw material for decomposition is called:Which is NOT a step of decomposition?Plants capture what share of photosynthetically active radiation?Decomposition is slower when detritus is rich in:Which conditions favour decomposition?The mass of living material at a trophic level is the:The pyramid of biomass in the sea is generally:Which ecological pyramid can never be inverted?Which group is left out of ecological pyramids?What is the vertical distribution of species at different levels in an ecosystem called?Identifying and listing the plant and animal species of an ecosystem gives its what?In a forest, which plants occupy the topmost vertical layer?Which of these is NOT one of the four aspects through which ecosystem components function as a unit?Which organisms form the autotrophic part of a pond ecosystem?Which group acts as the decomposers at the bottom of a pond?In a pond ecosystem, zooplankton and swimming animals represent which component?How does energy move through the trophic levels of an ecosystem?Biomass produced per unit area over a period of time by plants during photosynthesis is called what?Net primary productivity is gross primary productivity minus what?Net primary productivity is the biomass available to which organisms?The rate of formation of new organic matter by consumers is termed what?Roughly how much dry organic matter does the whole biosphere add as annual net primary productivity?Oceans cover about 70 percent of Earth's surface. How much annual NPP do they account for?What do detritivores such as earthworms do to detritus?Dead plant remains, dead animals and faecal matter together make up what?Humification leads to the accumulation of which dark amorphous substance?Why does humus act as a reservoir of nutrients?Which process releases inorganic nutrients when microbes degrade humus?Decomposition is largely a process that requires which substance?Apart from deep sea hydrothermal systems, what is the only energy source for ecosystems?What fraction of PAR do plants capture to sustain the entire living world?Which organisms are the main producers in an aquatic ecosystem?Primary consumers in a food chain are always which kind of organism?The detritus food chain begins with what?Decomposers such as fungi and bacteria are also known as what?Which food chain is the major conduit for energy flow in an aquatic ecosystem?In a terrestrial ecosystem, which food chain carries a larger fraction of the energy?What forms when natural food chains interconnect?Which organisms occupy the second trophic level?Why is biomass measured in dry weight preferred over fresh weight?The number of trophic levels in a grazing food chain is limited because of what?What happens to the amount of energy at successive trophic levels?Which of these is NOT an ecological pyramid usually studied?What does the base of an ecological pyramid represent?A trophic level represents which of the following?The energy pyramid is always upright because energy is lost in what form at each step?In which ecosystem is the pyramid of biomass generally inverted?In most ecosystems, what shape do pyramids of number, biomass and energy take?Which group finds no place in ecological pyramids despite playing a vital role?An ecosystem is best described as what kind of unit of nature?Which are the two main structural features of an ecosystem?What is primary production at its most basic level?How does a rise in temperature affect microbial decomposition?A volcanic eruption that leaves soil without plants, animals or organic matter leads to which process?A forest fire or hurricane is a less severe disturbance. It typically results in what?The conversion of ammonium to nitrite and nitrate ions by soil bacteria is called what?Mycorrhizal fungi pass phosphorus and nitrogen compounds to plant roots in return for what?A keystone species affects ecosystem function in what way?What is an ecosystem engineer?Primary succession occurs after colonization of which kind of habitat?Secondary succession follows which event?In Clements' stages of succession, what is nudation?Which stage of succession involves establishment and initial growth of vegetation?Which stage of succession ends when a stable climax community forms?What is a seral community?What is the end point of succession, in equilibrium with its habitat, called?What is true of organic matter accumulation in a climax community?In a climax ecosystem, gross primary production is balanced by what?What is a prisere?