Do you need some help in preparing for your upcoming Class 12 Biology exam? We’ve compiled a list of MCQ questions on Ecosystem Class 12 MCQs Questions with Answers to get you started with the subject. You can download NCERT MCQ Questions for Class 12 Biology Chapter 14 Ecosystem with Answers Pdf free download, and learn how smart students prepare well ahead MCQ Questions for Class 12 Biology with Answers.
Ecosystem Class 12 MCQs Questions with Answers
Solve this Ecosystem Multiple Choice Questions of Class 12 Biology Chapter 14 MCQ, so as not to miss out on any concept from being clear about what they mean!
Select the correct answer
Question 1.
Decomposers like fungi and bacteria are:
(i) autotrophs
(ii) heterotrophs
(iii) saprotrophs
(iv) chemo-autotrophs
Choose the correct answer:
(a) i and iii
(b) i and iv
(c) ii and iii
(d) i and ii.
Answer
Answer: (c) ii and iii
Question 2.
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
Answer: (a) inorganic nutrients from humus
Question 3.
Productivity is the rate of production of biomass expressed in terms of:
(i) (kcal m-1) yr-1
(ii) g-2yr-1
(iii) g-1 yr-1
(iv) (kcal m-2 yr-1
(a) ii
(b) iii
(c) ii and iv
(d) i and iii.
Answer
Answer: (c) ii and iv
Question 4.
An inverted pyramid of biomass can be found in which ecosystem?
(a) Forest
(b) Marine
(c) Grassland
(d) Tundra.
Answer
Answer: (b) Marine
Question 5.
Which of the following is not a producer?
(a) Spirogyra
(b) Agaricus
(c) Volvox
(d) Nostoc.
Answer
Answer: (b) Agaricus
Question 6.
Which of the following ecosystems is most productive in terms of net primary production?
(a) Deserts
(b) Tropical rainforests
(c) Oceans
(d) Estuaries.
Answer
Answer: (b) Tropical rainforests
Question 7.
Pyramid of numbers is:
(a) Always upright
(b) Always inverted
(c) Either upright or inverted
(d) Neither upright nor inverted.
Answer
Answer: (c) Either upright or inverted
Question 8.
Approximately how much of the solar energy that falls on the leaves of a plant is converted to chemical energy by photosynthesis?
(a) Less than 1%
(b) 2-10%
(c) 30%
(d) 50%.
Answer
Answer: (b) 2-10%
Question 9.
Among the following, where do you think the process of decomposition would be the fastest?
(a) Tropical rainforest
(b) Antarctic
(c) Dry arid region
(d) Alpine region.
Answer
Answer: (a) Tropical rainforest
Question 10.
How much of the net primary productivity of a terrestrial ecosystem is eaten and digested by herbivores?
(a) 1%
(b) 10%
(c) 40%
(d) 90%.
Answer
Answer: (b) 10%
Question 11.
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
Answer: (a) Orderly and sequential
Question 12.
Climax community is in a state of:
(a) non-equilibrium
(b) equilibrium
(c) disorder
(d) constant change.
Answer
Answer: (b) equilibrium
Question 13.
Among the following biogeochemical cycles which one does not have losses due to respiration?
(a) Phosphorus
(b) Nitrogen
(c) Sulphur
(d) All of the above.
Answer
Answer: (d) All of the above.
Question 14.
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.
Answer
Answer: (b) phytoplankton, free-floating hydrophytes, rooted hydrophytes, sedges, grasses and trees.
Question 15.
The reservoir for the gaseous type of bio-geochemical cycle exists in
(a) stratosphere
(b) atmosphere
(c) ionosphere
(d) lithosphere.
Answer
Answer: (b) atmosphere
Question 16.
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.
Answer
Answer: (c) tertiary consumer
Question 17.
Which of the following types 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.
Answer
Answer: (c) Desert
Question 18.
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.
Answer
Answer: (d) Littoral zone.
Question 19.
Edaphic factor refers to:
(a) Water
(b) Soil
(c) Relative humidity
(d) Altitude.
Answer
Answer: (b) Soil
Question 20.
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.
Answer
Answer: (d) All of the above.
Assertion and Reason Type Questions
The questions given below consist of an assertion and a reason. Use the following key to choose the appropriate answer.
(a) Both Assertion and Reason are true and Reason is a correct explanation of the Assertion.
(b) Both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
(c) Assertion is true but Reason is false.
(d) If both Assertion and Reason are false.
Question 21.
Assertion: Energy pyramid is slopping.
Reason: The energy of one trophic level is lower than the preceding trophic level.
Answer
Answer: (a) Both Assertion and Reason are true and Reason is a correct explanation of the Assertion.
Question 22.
Assertion: Alpine forests consist of dwarf shrubs mainly of junipers, silver firs and Rhododendrons.
Reason: Alpine forests occur in the Himalayas above the altitude of 3500 metres.
Answer
Answer: (a) Both Assertion and Reason are true and Reason is a correct explanation of the Assertion.
Question 23.
Assertion: In a food chain, members of successive higher levels are fewer in number.
Reason: Number of organisms at any trophic level depends upon the availability of organisms which serve as food at the lower level.
Answer
Answer: (b) Both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
Question 24.
Assertion: Tropical rainforests are disappearing fast from developing countries such as India.
Reason: No value is attached to these forests because these are poor in biodiversity.
Answer
Answer: (c) Assertion is true but Reason is false.
Question 25.
Assertion: No two species within a given community can have exactly the same niche.
Reason: The hahitat of a species together with the functions forms its niche.
Answer
Answer: (b) Both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
Question 26.
Assertion: Red algae contribute in producing coral reefs.
Reason: Some red algae secrete and deposit calcium carbonate over their walls.
Answer
Answer: (a) Both Assertion and Reason are true and Reason is a correct explanation of the Assertion.
Question 27.
Assertion: A network of food chains existing together in an ecosystem is known as a food web.
Reason: An animal like kite cannot be a part of a food web.
Answer
Answer: (b) Both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
Question 28.
Assertion: Animals adapt different strategies to survive in hostile environment.
Reason: Praying mantis is green in colour which merges with plant foliage.
Answer
Answer: (b) Both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.
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