Students of class 12 Biology should refer to MCQ Questions Class 12 Biology Ecosystem with answers provided here which is an important chapter in Class 12 Biology NCERT textbook. These MCQ for Class 12 Biology with Answers have been prepared based on the latest CBSE and NCERT syllabus and examination guidelines for Class 12 Biology. The following MCQs can help you to practice and get better marks in the upcoming class 12 Biology examination

Chapter 14 Ecosystem MCQ with Answers Class 12 Biology

MCQ Questions Class 12 Biology Ecosystem provided below have been prepared by expert teachers of grade 12. These objective questions with solutions are expected to come in the upcoming Standard 12 examinations. Learn the below provided MCQ questions to get better marks in examinations.

Question. What will happen if decomposer are completely removed from the ecosystem? will be blocked
(a) There will be no energy flow.
(b) There will be an increase in the number of detrivores.
(c) Herbivores will not receive solar energy.
(d) The movement of minerals in an ecosystem will be blocked.

Question. The amount of living biomass present in a unit area of an ecosystem at a given time is referred to as:
(a) Standing state
(b) Standing crop
(c) Gross primary productivity
(d) Net primary productivity

Question. “Good ozone” is found in the-
(a) Mesosphere
(b) Troposphere
(c) Stratosphere
(d) Ionosphere

Question. Match the items in Column-A and Column-B and choose the correct answer.

Column-A	Column-B
i. Koel	A. Methanobacterium
ii. Mycorrhiza	B. Trichoderma
iii. Biological control	C. Brood parasitism
iv. Biogas	D. Glomus

The correct answer is-
(a) i-B, ii-D, iii-C, iv-A
(b) i-C, ii-D, iii-B, iv-A
(c) i-D, ii-A, iii-B, iv-C
(d) i-C, ii-B, iii-A, iv-D

Question. Find the incorrect statement.
(a) In terrestrial ecosystem larger fraction of energy flow occurs through DFC.
(b) Pyramid of energy is always upright.
(c) In comparison to food chain food webs are more stable.
(d) Detritus food chain is not at all connected with grazing food chain at any level.

Question. The rate of synthesis of organic matter by consumers is-
(a) Net primary productivity
(b) Gross primary productivity
(c) Standing state
(d) Secondary productivity

Question. The primary treatment basically involves the physical removal of particles from the sewage through?
(a) Filtration
(b) Sedimentation
(c) Microbial treatment
(d) Both 1 and 2

Question. Match the Column-I and Column-II and choose the correct answer.

The correct answer is-
(a) A-ii, B-i, C-iv, D-iii
(b) A-iii, B-ii, C-iv, D-i
(c) A-iii, B-iv, C-i, D-ii
(d) A-iii, B-i, C-iv, D-ii

Question. In which of the following ecosystem productivity is about 55million tones?
(a) Forest
(b) Grassland
(c) Agroecosystem
(d) Oceans

Question. Adaption is an attribute of the organism (morphological, physiological, and behavioral) that enables the organism to-
(a) Survive in its habitat
(b) To reproduce in his habitat
(c) Survive and reproduce in its habitat
(d) Evolve in its habitat

Question. Which of the following is not a feature of typical r-selected species?
(a) On-time big bang reproduction
(b) Large number of offspring’s in a single mating
(c) Small-sized offspring
(d) Long life span

Question. Identify the incorrect statement regarding ecotone-
(a) It is the transition zone between two communities.
(b) It contains species from both the community.
(c) The total number of species is less in the ecotone than in its adjoining communities.
(d) All of the above.

Question. Consider the following four statement select the correct option stating which ones are true(T) and which ones are false(F)-
1. An organisms at each trophic level depends on those at a higher trophic levels for their energy demands.
2. Each trophic levels has a certain mass of living material at a particular time called that the standing crop.
3. Each trophic levels has a certain mass of non-living inorganic material at a particular time called that the standing state.
4. The number of trophic levels in a grazing food chain is not restricted.
(a) 1-T, 2-T, 3-F, 4-F
(b) 1-F, 2-T, 3-F, 4-T
(c) 1-T, 2-F, 3-T, 4-F
(d) 1-F, 2-T, 3-T, 4-F

Question. If BOD sample water is very high the sample is-
(a) Highly polluted
(b) Less polluted
(c) Not polluted
(d) Potable

Question. Choose the correct statement regarding the catalytic converters-
(a) Motor vehicles equipped with catalytic converter should use leaded petrol.
(b) Catalytic converters have expensive metals namely platinum-palladium and rhodium as catalyst.
(c) Catalytic converters help in reducing particulate matter
(d) As the exhaust passes through the catalytic converter nitrogen gas is converted to nitric oxide.

Question. Which of the following is not a characteristic feature of the humus?
(a) It is a dark coloured, amorphous substance
(b) Highly resistant to microbial action
(c) It is reservoir of nutrients
(d) Cannot be degraded further

Question. Minamata disease is caused due to the consumption of-
(a) Sea food, containing lot of cadmium
(b) Fish contaminated with mercury
(c) Oysters with lot of pesticide
(d) Sea food, containing with selenium

Question. Read the following statements w.r.t. predation and select the two wrong statements-
I. Predators help in maintaining species diversity in a community.
II. Predators in nature are prudent.
III. Predators cannot reduce the intensity of competition among competing prey species.
IV. Predators do not act as conducts for energy transfer across trophic levels.
(a) I and II
(b) III and IV
(c) I and III
(d) II and III `

Question. Which of the following is not an example of ex-situ conservation?
(a) Seed bank
(b) Zoo
(c) Sanctuaries
(d) Botanical gardens

Question. Following are the roles of predation except-
(a) It helps in maintaining species diversity in a community.
(b) It is a potent force of organic evolution.
(c) Predators act as ‘conduits’ of energy transfer across trophic levels.
(d) The population of prey is kept under control by the predators.

Question. The species composition that invades a barren area and drives the succession is called:
(a) a climax community
(b) a pioneer community
(c) the keystone species
(d) the standing crop

Question. Which of the following is a mismatch?
(a) AIR (Prevention and Control of Pollution) act-1981.
(b) Concept of Joint Forest Movement- Introduced by government in 1980.
(c) Ramesh Chandra Dagar – Worked on integrated organic farming.
(d) Water (Prevention and Control of Pollution) act-1986.

Question. If birth and death rates were equal, a zero population growth rate would result. It is known as-
(a) Replacement level
(b) Rate of natural increase
(c) Stable population
(d) Doubling time

Question. Which of the following is not an insectivorous plant-?
(a) Drosera
(b) Nepenthes
(c) Monotropa
(d) Utricularia

Question. When environmental conditions are favorable, then the population growth curve will be-
(a) Hyperbola
(b) ‘J’ Shaped
(c) ‘S’ shaped
(d) None of these

Question. Mass of living matter at a trophic level in an area at any time is called
(a) standing crop
(b) detritus
(c) humus
(d) standing state

Question. Which one of the following is not a gaseous biogeochemical cycle in ecosystem?
(a) Oxygen cycle
(b) Phosphorus cycle
(c) Nitrogen cycle
(d) Carbon cycle

Question. There is no difference between
(a) secondary consumers and herbivores.a
(b) primary consumers and herbivores.
(c) first trophic level and herbivores.
(d) primary carnivores and second trophic level

Question. Pyramid of numbers is
(a) always upright
(b) always inverted
(c) either upright or inverted
(d) neither upright nor inverted

Question. Which of the following compartments of the global ecosystem would be characterized by very slow movement of materials within the compartment ?
(a) Oceans
(b) Fresh water
(c) Atmosphere
(d) Land

Question. Identify the possible link “A” in the following food chain.
Plant → insect → frog → “A” → eagle
(a) rabbit
(b) wolf
(c) cobra
(d) parrot

Question. Which one of the following is not a functional unit of an ecosystem?
(a) Energy flow
(b) Decomposition
(c) Productivity
(d) Stratification

Question. Which statement is true corresponding to the given food chain ?
Grass → Rabbits → Snakes → Hawks
(a) Each predator population has a greater biomass than its prey population.
(b) Each prey population has a greater biomass than its predator population.
(c) Each population is omnivorous.
(d) Each level of food chain returns inorganic nutrients and energy to the producer.

Question. The upright pyramid of number is absent in
(a) pond
(b) forest
(c) lake
(d) grassland

Question. The rate of formation of new organic matter by rabbit in a grassland, is called
(a) net productivity
(b) second productivity
(c) net primary productivity
(d) gross primary productivity

Question. The process of mineralisation by microorganisms helps in the release of
(a) inorganic3 nutrients from humus
(b) both organic and inorganic nutrients from detritus
(c) organic nutrients from humus
(d) inorganic nutrients from detritus and formation of humus.

Question. An inverted pyramid of biomass can be found in which ecosystem?
(a) Forest
(b) Marine
(c) Grass land
(d) Tundra

Question. Which of the following ecosystems is most productive in terms of net primary production?
(a) Deserts
(b) Tropical rain forests
(c) Oceans
(d) Estuaries

Question. If the carbon atoms fixed by producers already have passed through three species, the trophic level of the last species would be:
(a) scavenger
(b) tertiary producer
(c) tertiary consumer
(d) secondary consumer

Question. Of the total amount of energy that passes from one trophic level to another, about 10% is
(a) respired and becomes heat
(b) passed out as faces or urine
(c) stored as body tissue
(d) recycled to autotrophs

Question. Climax community is in a state of
(a) non-equilibrium
(b) equilibrium
(c) disorder
(d) constant change.

Question. Which one of the following is not used for construction of ecological pyramids?
(a) Number of individuals
(b) Rate of energy flow
(c) Fresh weight
(d) Dry weight

Question. Among the following bio-geo-chemical cycles which one does not have losses due to respiration?
(a) Phosphorus
(b) Nitrogen
(c) Sulphur
(d) All of the above

Question. The sequence of communities of primary succession in water is
(a) phytoplankton, sedges, free-floating hydrophytes, rooted hydrophytes, grasses and trees.
(b) phytoplankton, free-floating hydrophytes, rooted hydrophytes, sedges, grasses and trees.
(c) free-floating hydrophytes, sedges, phytoplankton, rooted hydrophytes, grasses and trees.
(d) phytoplankton, rooted submerged hydrophytes, floating hydrophytes, reed swamp, sedges,meadow and trees.

Question. The reservoir for the gaseous type of bio-geo chemical cycle exists in
(a) stratosphere
(b) atmosphere
(c) ionosphere
(d) lithosphere

Question. Productivity is the rate of production of biomass expressed in terms of
(i) (kcal m–3) yr–1 (ii) g–2 yr–1
(iii) g–1 yr–1 (iv) (kcal m–2) yr–1
(a) (ii) (b) (iii)
(b) (ii) and (iv)
(c) (i) and (iii)

Question. Humans benefit from ecosystems because ecosystems provide
(a) buffers from natural disasters such as floods.
(b) maintenance of a clean water supply.
(c) climate moderation.
(d) All of the above

Question. Which of the following type of ecosystem is expected in an area where evaporation exceeds precipitation, and mean annual rainfall is below 100 mm?
(a) Grassland
(b) Shrubby forest
(c) Desert
(d) Mangrove

Question. The zone at the edge of a lake or ocean which is alternatively exposed to air and immersed in water is called:
(a) pelagic zone
(b) benthic zone
(c) lentic one
(d) littoral zone

Question. Edaphic factor refers to:
(a) water
(b) soil
(c) relative humidity
(d) altitude

Question. Which of the following is an ecosystem service provided by a natural ecosystem?
(a) Cycling of nutrients
(b) Prevention of soil erosion
(c) Pollutant absorption and reduction of the threat of global warming
(d) All of the above

Question. A succession of communities on barren land, is known as
(a) secondary succession
(b) primary succession
(c) tertiary succession
(d) none of these

Question. Vertical distribution of different species occupying different levels is called
(a) enumeration
(b) stratification
(c) species composition
(d) none of these

Question. Primary productivity
(a) is equal to the standing crop of an ecosystem.
(b) is greatest in freshwater ecosystems.
(c) is the rate of conversion of light to chemical energy in an ecosystem.
(d) is inverted in some aquatic ecosystems.

Question. Which one of the following process help the watersoluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts?
(a) Fragmentation
(b) Leaching
(c) Catabolism
(d) Humification

Question. In a food web, each successive trophic level has
(a) increased total energy content
(b) less total energy content
(c) more total energy content
(d) non-estimated energy content

Question. The primary difference between sedimentary and atmospheric cycles is that in _____ cycles the nutrient does not _____.
(a) sedimentary; leave the terrestrial environment
(b) sedimentary; leave the aquatic environment
(c) atmospheric; leave the aquatic environment
(d) sedimentary; enter the atmosphere

Question. Which one of the following pairs is a sedimentary type of biogeochemical cycle ?
(a) Phosphorus and carbon monoxide
(b) Oxygen and nitrogen
(c) Phosphate and nitrogen
(d) Phosphorus and sulphur

Question. During the process of ecological succession the changes that take place in communities are
(a) orderly and sequential
(b) random
(c) very quick
(d) not influenced by the physical environment.

Question. Which one of the following statement is correct?
(a) Warm and moist environment favour decomposition whereas low temperature and anaerobiosis inhibit decomposition.
(b) Warm and moist environment inhibit decomposition whereas low temperature and anaerobiosis favour decomposition.
(c) Warm moist environment and anaerobiosis inhibit decomposition whereas low temperature favours decomposition.
(d) Warm and low temperature inhibit decomposition whereas anaerobiosis favours decomposition

Question. The given statements (i – iv) are the characteristics of productivity.
(i) The rate of biomass production is called productivity and is expressed in terms of a kcal m–2.
(ii) Net primary productivity is rate of production of biomass during photosynthesis.
(iii) Net primary productivity minus respiration loss is called net primary productivity.
(iv) Primary productivity depends only on the plant species inhabiting a particular area.
Identify the correct statements.
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (ii), (iii) and (iv)
(d) (ii) and (iv)

Question. Which of the following include(s) ecosystem services ?
(i) Purification of air and water by forests.
(ii) Forests mitigate droughts and flood.
(iii) Forests act as store house of carbon.
(iv) Forests influence hydrological cycle.
(a) (i) and (iii)
(b) (i) and (iv)
(c) (i), (ii) and (iii)
(d) All of these

Question. Productivity at the second trophic level is always
(a) greater than the productivity at the first trophic level.
(b) less than the productivity at the first trophic level.
(c) equal to the productivity at the first trophic level.
(d) extremely variable compared to the productivity at the first trophic level.

Question. Which one of the following animals may occupy more than one trophic levels in the same ecosystem at the same time?
(a) Sparrow
(b) Lion
(c) Goat
(d) Frog

Question. Which one of the following is not an abiotic component?
(a) Temperature
(b) Decomposers
(c) Water
(d) Soil

Question. What is the annual net primary productivity of whole biosphere?
(a) 170 billion tons (dry weight) of organic matter.
(b) 165 billion tons (dry weight) of organic matter.
(c) 160 billion tons (dry weight) of organic matter.
(d) 155 billion tons (dry weight) of organic matter.

Question. Identification and enumeration of plant and animal species of an ecosystem gives its
(a) productivity
(b) stratification
(c) species composition
(d) all of these

Question. Which of the following could not be considered an ecosystem ?
(a) A small pond
(b) All the fish in a coral reef
(c) Earth
(d) A pile of dung in a pasture

Question. Decomposers like fungi and bacteria are
(i) autotrophs (ii) heterotrophs
(iii) saprotrophs (iv) chemo-autotrophs
(a) (i) and (iii)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (i) and (ii)

Question. In ecological succession from pioneer to climax community, the biomass shall
(a) decrease
(b) increase and then decrease
(c) no relation between these communities
(d) increase continuously

Question. Which one is the correct food chain ?
(a) Eagle → Snake → Grasshopper → Grass → Frog
(b) Frog → Snake → Eagle → Grasshopper → Grass
(c) Grasshopper → Grass → Snake ® Frog → Eagle
(d) Grass → Grasshopper → Frog ® Snake → Eagle

We hope the above multiple choice questions for Class 12 Biology for Chapter 14 Ecosystem provided above with answers based on the latest syllabus and examination guidelines issued by CBSE, NCERT and KVS are really useful for you. Ecosystem is an important chapter in Class 12 as it provides very strong understanding about this topic. Students should go through the answers provided for the MCQs after they have themselves solved the questions. All MCQs have been provided with four options for the students to solve. These questions are really useful for benefit of class 12 students. Please go through these and let us know if you have any feedback in the comments section.