CBSE Class 12 Biology Ecosystem MCQs Set A

Practice CBSE Class 12 Biology Ecosystem MCQs Set A provided below. The MCQ Questions for Class 12 Chapter 12 Ecosystem Biology with answers and follow the latest CBSE/ NCERT and KVS patterns. Refer to more Chapter-wise MCQs for CBSE Class 12 Biology and also download more latest study material for all subjects

MCQ for Class 12 Biology Chapter 12 Ecosystem

Class 12 Biology students should review the 50 questions and answers to strengthen understanding of core concepts in Chapter 12 Ecosystem

Chapter 12 Ecosystem MCQ Questions Class 12 Biology with Answers

Question :  An ecosystem is a

a) group of components that interact with one another.
b) group of interacting species in one place at one time.
c) biological community and component of the physical environment with which the community interacts.
d) group of interacting chemicals and their cycles.

Answer : C

 

Question :  Which of the following is/are example(s) of man-made ecosystem?

a) Herbarium 
b) Crop fields
c) Aquarium  
d) Both b) and c)

Answer : D 


Question :  Vertical distribution of different species occupying different levels is called

a) enumeration           
b) stratification
c) species composition
d) none of these

Answer : B 


Question :  Which one of the following is not an abiotic component?

a) Temperature
b) Decomposers
c) Water           
d) Soil

Answer : B

 

Question :  In an ecosystem abiotic components includes which of the following ?

a) Flow of energy
b) Cycling of materials
c) Consumers
d) Flow of energy and cycling of materials

Answer : D 


Question :  Two main structural features of an ecosystem are

a) species composition and stratification
b) species composition and productivity
c) productivity and energy flow
d) nutrient cycling and stratification

Answer : A 


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

Answer : C 


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

Answer : C

 

Question :  The rate at which light energy is converted into chemical energy of organic molecules is the ecosystem’s

a) net primary productivity
b) gross secondary productivity
c) net secondary productivity
d) gross primary productivity

Answer : D 


Question :  Which of the following most often limits the primary productivity of the ecosystem ?

a) Solar radiation/light
b) Oxygen
c) Consumers             
d) Nitrogen

Answer : A

Question :  Decomposers like fungi and bacteria are:

i. autotrophs

ii. heterotrophs

iii. saprotrophs

iv. chemo-autotrophs.

Choose the correct answer

a) ii and iii,

b) i and ii

c) i and iv

d) i and iii

Answer : A

 

Question :  The process of mineralisation by micro organisms helps in the release of

a) inorganic 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

Answer :  A

 

Question :  An inverted pyramid of biomass can be found in which ecosystem?

a) Marine

b) Forest

c) Grass land

d) Tundra

Answer :  A

 

Question :  Which of the following is not a producer?

a) Agaricus

b) Nostoc

c) Volvox

d) Spirogyra

Answer :  A

 

Question :  Which of the following ecosystems is most productive in terms of net primary production?

a) Tropical rain forests

b) Deserts

c) Oceans

d) Estuaries

Answer :  A

 

Question :  Pyramid of numbers is

a) Ether upright or inverted

b) Always inverted

c) Always upright

d) Neither upright nor inverted.

Answer :  A

 

Question :  Energy flow in ecosystem is

a) Unidirectional

b) Multidirectional

c) Bidirectional

d) None of these

Answer :  A

 

Question :  Which one of the following is one of the characteristics of a biological community?

a) Stratification

b) Natality

c) Mortality

d) None of these

Answer :  A

 

Question :  Which of the following is an example of man-made ecosystem?

a) Aquarium

b) Herbarium

c) Tissue culture

d) All of these

Answer :  A

 

Question :  Approximately how much of the solar energy that falls on the leaves of a plant is converted to chemical energy by photosynthesis?

a) 2-10%

b) 30%

c) 50%

d) Less than 1%

Answer :  A

 

Question :  Among the following, where do you think the process of decomposition would be the fastest?

a) Tropical rain forest

b) Antarctic

c) Dry arid region

d) Alpine region

Answer :  A

 

Question :  How much of the net primary productivity of a terrestrial ecosystem is eaten and digested by herbivores?

a) 10%

b) 1%

c) 40%

d) 90%

Answer :  A

 

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.

Answer :  A

 

Question :  Climax community is in a state of

a) equilibrium

b) disorder

c) constant change

d) non-equilibrium

Answer : A

 

Question :  Among the following bio-geo-chemical cycles which one does not have losses due to respiration?

a) All of the above

b) Sulphur

c) Nitrogen

d) Phosphorus

Answer : A

 

Question :  These belong to the category of primary consumers

a) Insects and cattle

b) Snakes and Frogs

c) Eagle and snakes

d) Water insects

Answer : A

 

Question :  Which one of the following pairs in mismatched?

a) Prairie - epiphytes

b) Savanna - acacia trees

c) Coniferous forest - evergreen trees

d) Tundra - permafrost

Answer :  A

 

Question :  Presence of plants arranged into well defined vertical layers depending on their height can be seen best in

a) Tropical Rain Forest

b) Grassland

c) None of these

d) Temperate Forest

Answer : A

  

Question :  The term ecosystem was coined by

a) A.G. Tansley

b) E.P. Odum

c) E. Haeckel

d) E. Haeckel

Answer :  A

 

Question :  The sequence of communities of primary succession in water is

a) phytoplankton, rooted submerged hydrophytes, floating hydrophytes, reed swamp, sedges, meadow and trees

b) free-floating hydrophytes, sedges, phytoplankton, rooted hydrophytes, grasses and trees

c) phytoplankton, free-floating hydrophytes, rooted hydrophytes, sedges, grasses and trees.

d) phytoplankton, sedges, free-floating hydrophytes, rooted hydrophytes, grasses and trees.

Answer :A

 

Question :  The reservoir for the gaseous type of bio-geo chemical cycle exists in 

a) atmosphere

b) stratosphere

c) ionosphere

d) lithosphere

Answer :  A

 

Question :  If the carbon atoms fixed by producers already have passed through three species, the trophic level of the last species would be

a) tertiary consumer

b) secondary consumer

c) tertiary producer

d) scavenger

Answer :  A

 

Question :  Which of the following type of ecosystem is expected in an area where evaporation exceeds precipitation, and mean annual rainfall is below 100mm 

a) Desert

b) Mangrove

c) Grassland

d) Shrubby forest

Answer :  A

 

Question :  The zone at the edge of a lake or ocean which is alternatively exposed to air and immersed in water is called 

a) Littoral zone

b) Lentic one

c) Benthic zone

d) Pelagic zone

Answer :  A

 

Question :  Edaphic factor refers to 

a) Soil

b) Relative humidity

c) Altitude

d) Water

Answer :  A

 

Question :  Which of the following is an ecosystem service provided by a natural ecosystem? 

a) All of the above

b) Pollutant absorption and reduction of the threat of global warming

c) Prevention of soil erosion

d) Cycling of nutrients

Answer :  A

 

Question :  Which is the reason for highest biomass in aquatic ecosystem?

a) Benthonic and brown algae

b) Sea grass, and slime molds

c) Nanoplankton, blue green algae, green algae

d) None of these

Answer :  A

 

Question :  The average trophic efficiency of transfer of energy from one trophic level to the. higher trophic level is called 

a) Linderman's trophic efficiency rule

b) Linderman's trophic efficiency rule

c) Assimilation. Efficiency

d) All of these

Answer :  A

 

Question :  Secondary Succession takes place on/in 

a) Degraded forest

b) Bare rock

c) Newly cooled lava

d) None of these

Answer :  A 

 

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.

Answer : A

 

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

Answer : B

 

Question : How much portion of the photosynthetically active radiation (PAR) is captured by the plants?

a) 5 – 10%
b) 7 – 10%
c) 8 – 10%
d) 2 – 10%

Answer : D


Question : Energy flow in an ecosystem is

a) unidirectional  
 b) bidirectional
c) multidirectional
d) all of these

Answer : A

 

Question : Each trophic level has a certain mass of living material at a particular time is known as

a) catabolism  
b) standing crop
c) humification
d) primary productivity

Answer : B


Question :  Ecosystems are ______ because resources ____ move from one ecosystem to another.

a) open; can     
 b) closed; cannot
c) one-way; can
d) one-way; cannot

Answer : A


Question : Energy pyramids are used to represent energy transfer in an ecosystem because energy is _______ between each trophic level.

a) gained
b) lost
c) conserved
d) either conserved or gained

Answer : B

 

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

Answer : D

 

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

Answer : D


Question : Consider the following statements.
(i) An ecosystem is a functional unit of nature and comprises abiotic and biotic components.
(ii) Abiotic components are organic materials.
(iii) Biotic components are producers, consumers and decomposers.
(iv) Energy flow is bidirectional.
which two statements are correct ?

a) (i) and (ii)  
b) (ii) and (iv)
c) (iii) and (iv)
d) (i) and (iii)

Answer : D 

 

Question : A mutually beneficial association necessary for survival of both partners are 
a) mutualism/symbiosis
b) commensalism
c) amensalism
d) Both a) and b)
Answer : A
 
Question : The relation between algae and fungi in a lichen is 
a) symbiosis       
b) parasitism
c) commensalism
d) protocooperation
Answer : A
 
Question : Pyramid of numbers in a grassland/true eco- system is 
a) always inverted
b) always upright
c) Both a) and b)
d) spindle-shaped
Answer : B
 
Question : Pick up the correct food chain 
a) Grass -> Chaemeleon -> Insect -> Bird
b) Grass -> Fox -> Rabbit -> Bird
c) Phytoplankton -> Zooplankton -> Fish
d) Fallen leaves -> Bacteria -> Insect larvae
Answer : C
 
Question : Food chain in which micro-organisms break- down the food formed by primary producers are                                                    
a) parasitic food chain
b) detritus food chain
c) consumer food chain
d) predator food chain
Answer : B
 
Question : The sum total of the population of the same kind of organisms constitute 
a) colony       
b)  genus
c) community
d) species
Answer : D
 
Question : Pyramid of number deals with number of 
a) species in an area
b) individuals in a community
c) individuals in a trophic level
d) sub-species in a community
Answer : C
 
Question : Study of inter-relationships between living organisms and their environment is 
a) Ecology
b) Ecosystem
c) Phytogeography
d) Ethology
Answer : A
 
Question : Pyramid of number in a pond ecosystem is
a) irregular
b)  inverted
c)  upright
d) spindle-shaped
Answer : C
 
Question : In grass-deer-tiger food chain, grass biom- ass is one tonne. The tiger biomass shall be 
a) 100 kg
b) 10 kg
c) 200 kg
d) 1 kg
Answer : B
 
Question : In a biotic community, the most important factor for survival of an animal is 
a) day length
b)  soil moisture
c) green food
d) predators
Answer : C
 
 
Question : The pyramid which cannot be inverted in a stable ecosystem is that of 
a) biomass
b)  number
c) energy
d) All of these
Answer : C
 
Question : In a food chain, the largest population is that of 
a) producers
b) decomposers
c) secondary consumers
d) primary consumers
Answer : A
 
Question : Second most important trophic level in a lake 
a) zooplankton
b)  phytoplankton
c) benthos
d) neuston
Answer : A
 
Question : Which of the following is the most stable eco-system? 
a) Forest
c) Mountain
b) Desert
d) Ocean
Answer : D
 
Question : The primary succession refers to the devel- opment of communities on a 
a) fleshly cleared crop field
b) forest clearing after devastating fire
c) pond, freshly filled with water after a dry phase
d) newly-exposed habitat with no record of earlier vegetation
Answer : D
 
Question : Mycorrhiza is a symbiotic relationship be- tween roots of higher plants and 
a) virus
b)  fungi
c) bacteria
d) blue-green algae
Answer : B
 
Question : Which of the following can fix atmospheric nitrogen? 
a) Albugo
b) Cystopus
c) Saprolegnia
d) Anabaena 
Answer : D
 
Question : In a biotic community, the primary consum-ers are 
a) carnivores
c) detritivores
b)  omnivores
d) herbivores
Answer : D
 
Question : Which of the following pair is a sedimen- tary type of biogeochemical cycle? 
a) Oxygen and nitrogen
b) Phosphorus and sulphur
c) Phosphorus and nitrogen
d) Phosphorus and carbon dioxide
Answer : B
 
Question : If we completely remove the decomposers, from an ecosystem, its functioning will be adversely affected, because  
a) energy flow will be blocked
b) herbivores will not receive solar energy
c) mineral movement will be blocked
d) rate of decomposition will be very high
Answer : C
 
Question : The transfer of energy from one trophic level to another is governed by the 2nd law of ther- modynamics. The average efficiency of en- ergy transfer from herbivores to carnivores is 
a) 5%
b) 10%
c) 25%
d) 50%
Answer : B
 
Question : The nature of climax community ultimately depends on          
a) climate
b) bed rock
c) soil organisms
d) pool of available nutrients
Answer : A
 
Question : In a food chain, the largest population is that of  
a) decomposers
b) producers
c) primary consumers
d) tertiary consumers
Answer : B
 
Question : Niche of a species in an ecosystem refers to its     
a) function at its place of occurrence
b) place of its occurrence
c) competitive ability
d) centre of origin
Answer : A
 
Question : Which of the following ecosystem has the highest gross primary productivity? 
a) Grasslands
b) Coral reefs
c) Mangroves
d) Equatorial rain forest
Answer : B
 
Question : Keystone species in an ecosystem are those which     
a) are present in maximum number
b) are most frequent
c) attain a large biomass
d) contribute to ecosystem properties
Answer : B
 
Question : Which of the following is free-living aerobic non-photosynthetic nitrogen-fixing bacte- rium? 
a) Rhizobium       
b)  Azotobacter
c) Nostoc             
d) Azospirillum
Answer : B
 
Question :   An orchid resembling the female of an in- sect so as to be able to get pollinated is due to phenomenon of   
a) mimicry
b) pseudocopulation
c) pseudopollination
d) pseudoparthenocarpy
Answer : A
 
Question : Species restricted to a given area are called
a) sibling                
b) endemic
c) sympatric          
d) allopatric
Answer : B
 
Question : Plants  such  as  Prosop is,  Acaciaand Capparis represent examples of tropical 
a) grasslands
b) thorn forests
c) deciduous forests
d)  evergreen forests
Answer : B
 
Question : the rate at which light energy is converted into chemical energy of organic molecules is the ecosystem’s          
a) net primary productivity
b) gross secondary productivity
c) net secondary productivity
d) gross primary productivity
Answer : D

Question : In a terrestrial ecosystem such as forest, maxi- mum energy is in which trophic level ?
a) T1                                      
b) T2
c) T3                                      
d) T4
Answer : A

Question : Which part of the world has high density of organisms? 
a) Deciduous forests
b) Grasslands
c) Savannas
d) Tropical rain forests
Answer : D

 

Question : The maximum biomagnification would be in which of the following in case of aquatic ecosystem ?  
a) Fishes                 
b)  Phytoplanktons
c) Birds                   
d) Zooplanktons
Answer : A

 

Question : The greatest biomass of autotrophs in the world’s oceans is that of   
a) benthic brown algae, coastal red algae and daphnids
b) benthic diatoms and marine viruses
c) sea grasses and slime molds
d) free-floating micro-algae, cyanobacteria and nanoplankton
Answer : D

 

Question : Which type of association is found in be- tween entomophilous flower and pollinat- ing agent?            
a) Mutualism      
b)  Commensalism
c) Cooperation     
d) Co-evolution
Answer : A

 

Question : Two different species cannot live for long duration in the same niche or habitat. This law is   
a) Allen’s law
b) Mendel’s law
c) Gause’s competitive exclusion principal
d) Weismann’s theory
Answer : C

 

Question : Cause of mimicry is    
a) attack (offence)
b) protection (defence)
c) Both a) and b)
d) isolation
Answer : C

 

Question : Choose the correct match Bladderwort, sun- dew, venus fly trap 
a) Nepenthes, Dionea, Drosera
b) Nepenthes, Utricularia, Vanda 
c) Utricularia, Drosera, Dionea
d) Dionea, Trapa, Vanda
Answer : C

 

Question : Bamboo plant is growing in a far forest then what will be the trophic level of it?    
a) First trophic level (T1)
b) Second trophic level (T2)
c) Third trophic level (T3)
d) Fourth trophic level (T4)
Answer : A

 

Question : What is true for individuals of same species?
a) Live in same niche
b) Live in same habitat
c) Interbreeding
d) Live in different habitats
Answer : C

 

Question : In which condition, the gene ratio remains constant for any species ?               
a) Sexual selection
b) Random mating
c) Mutation
d) Gene flow
Answer : B

 

Question : Which of the following is a correct pair?
a) Cuscuta — Parasite
b) Dischidia — Insectivorous
c) Opuntia — Predator
d) Capsella —Hydrophyte
Answer : A

 

Question : Two different species cannot live for long duration in the same niche or habitat. This law is                           
a) Allen’s law       
b)  Gause’s hypothesis
c) Dollo’srule       
d) Weismann’s theory
Answer : B

 

Question : Which of the following is most important for speciation?                                            
a) Seasonal isolation
b) Reproductive isolation
c) Behavioural isolation
d) Tropical Isolation
Answer : B

 

Question : Reason of fast speciation in present day crop plants is               
a) mutation           
b)  isolation
c) polyploidy       
d) sexual reproduction
Answer : C

Question : Mycorrhiza is an example of                
a) endoparasitism     
b)  decomposers
c) symbiotic relationship
d) ectoparasitism
Answer : C

 

Question : Escherichia coli is used as an indicator or- ganism to determine pollution of water with 
a) industrial effluents
b) pollen of aquatic plants
c) heavy metals
d) faecal matter
Answer : D

 

Question : Species are considered as                     
a) artificial concept of human mind which cannot be defined in absolute terms
b) real units of classification devised by taxonomists
c) real basic units of classification
d) the lowest units of classification
Answer : C

 

Question : What is a keystone species ?                 
a) A species which makes up only a small proportion of the total biomass  of a community, yet has a huge impact on the community’s organization and survival
b) A common species that has plenty of biomass, yet has a fairly low impact on the community’s organization
c) A rare species that has minimal impact on the biomass and on other species in the community
d) A dominant species that constitutes a large proportion of the biomass and which affects many other species
Answer : A

 

Question : Which of the following is expected to have the highest  value (gm/m2/yr) in a grass- land ecosystem?         
a) Secondary Production (SP)
b) Tertiary Production (TP)
c) Gross Production (GP)
d) Net Production (NP)
Answer : C

 

Question : An ecosystem which can be easily damaged but can recover after some time if damaging effect stops, will be having                 
a) low stability and high resilience
b) high stability and low resilience
c) low stability and low resilience
d) high stability and high resilience
Answer : A

Question : Lichens are well known combination of an alga and a fungus where fungus has  
a) a saprophytic relationship with the alga
b) an epiphytic relationship with the alga
c) a parasitic relationship with the alga
d) a symbiotic relationship with the alga
Answer : D

Question : There exists a close association between the alga and the fungus within a lichen. The fun- gus      
a) provides protection, anchorage and absorption for the alga
b) provides food for the alga
c) fixes the atmospheric nitrogen for the alga
d) release oxygen for the alga
Answer : A

Question : Animals have the innate ability to escape from predation. Examples for the same are given below. Select the incorrect example
a) enlargement of body size by swallowing air in puffer fish
b) melanism in moths
c) poison fangs in snakes
d) colour change in Chamaeleon
Answer : C

Question : Which one of the following pairs is mis- matched ?         
a) Savanna —Acacia trees
b) Prairie — Epiphytes
c) Tundra — Permafrost
d) Coniferous forest — Evergreen trees
Answer : B

Question : Praying mantis is a good example of
a) warning colouration
b) social insects
c) camouflage
d) Mullerian mimicry
Answer : C

Question : Which of the following is not true for a spe- cies?                                                      
a) Members of a species can interbreed
b) Variations occur among members of a species
c) Each species is reproductively isolated from every other species
d) Gene flow does not occur between the populations of a species
Answer : D

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

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Chapter 12 Ecosystem
CBSE Class 12 Biology Ecosystem MCQs Set A
CBSE Class 12 Biology Ecosystem MCQs Set B
CBSE Class 12 Biology Ecosystem MCQs Set C
CBSE Class 12 Biology Ecosystem MCQs Set D

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MCQs for Chapter 12 Ecosystem Biology Class 12

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