CBSE Questions for Class 12 Medical Biology Ecosystem Quiz 8 - MCQExams.com

Which of the following represents sedimentary type of nutrient cycle?
  • Nitrogen
  • Carbon
  • Phosphorus
  • Oxygen
Which is correct for secondary succession?
  • It follows primary succession
  • It is similar but faster than primary succession
  • It begins on bare rock
  • It occurs on deforested site
The circulation or cycling of elements in an ecosystem is known as
  • Geological cycling
  • Geo-chemical cycling
  • Bio-geochemical cycling
  • Nutrient cycling
Pyramid of numbers in a forest ecosystem is
  • Upright
  • Inverted
  • Irregular
  • Linear
Which of the following occurs in abiotic component of an ecosystem?
  • Flow of energy
  • Cycling of materials
  • Consumers
  • Flow of energy and cycling of materials
Relationships in an ecosystem can be depicted through
  • Pyramid of energy
  • Pyramid of biomass
  • Pyramid of numbers
  • All of the above
Pyramid of numbers in a pond ecosystem is
  • Irregular
  • Inverted
  • Upright
  • Spindle shaped
A habitat not suitable for primary productivity is
  • Cave
  • Pond
  • Meadow
  • Forested river bank
Who proposed the concept of ecological pyramids?
  • Odum
  • Clements
  • Tansley
  • Elton
In lake ecosystem, the pyramid of biomass is generally
  • Spindle - shaped
  • Inverted
  • Upright
  • Horizontal
Ecological pyramids are of ______ types.
  • Two
  • Three
  • Four
  • Five
Which of the following is correct?
  • Least productive ecosystem is desert and deep lake
  • Sugarcane is the most productive agroecosystem
  • Most productive is coral reef system
  • All of the above
Total amount of living material at various levels of a food chain is depicted by
  • Pyramid of energy
  • Pyramid of numbers
  • Pyramid of biomass
  • All of the above
An aquatic ecosystem with maximum primary productivity is
  • Ocean
  • Pond
  • Estuary
  • River
Pyramid of energy in a pond ecosystem is always
  • Linear
  • Inverted
  • Upright
  • Irregular
Rate of conversion of light energy into chemical energy of organic molecules in an ecosystem is called
  • Net primary productivity
  • Gross primary productivity
  • Net secondary productivity
  • Gross secondary productivity
In upright pyramid of biomass, herbivores occupy the position
  • 1
  • 2
  • 3
  • 4
Which one has always an upright/ steeper vertical gradient?
  • Pyramid of mass
  • Pyramid of energy
  • Pyramid of numbers
  • Pyramid of energy in aquatic ecosystem
Pyramid of energy is always upright indicating that
  • Producers have the lowest energy conversion efficiency.
  • Carnivorous have a better energy efficiency than herbivores.
  • Energy conversion efficiency is same for all trophic levels.
  • Herbivores have a better energy conversion efficiency than carnivores.
The accompanying figure represents an ecological pyramid. It is
697156_9f2241a1db2b44f7855cc64944b63830.png
  • Pyramid of numbers in grassland
  • Pyramid of biomass in fallow land
  • Pyramid of biomass in lake
  • Energy pyramid in a spring
Relationship between different organisms can best be studied by
  • Food webs
  • Pyramid of mass
  • Pyramid of energy
  • Eltonian pyramids
Weathering of rocks makes phosphorus available to first
  • Producers
  • Decomposers
  • Consumers
  • All of the above
Pyramid of number in grass ecosystem is
  • Linear
  • Upright
  • Inverted
  • Negative
The term ecosystem development to ecological succession was given by
  • Odum
  • Clements
  • Mishra
  • Blackman
Slow rate of decomposition of fallen logs in nature is due to
  • Anaerobic environment around them
  • Low cellulose contents
  • Low moisture content
  • Poor nitrogen content
Primary productivity of the ecosystem is most often limited by
  • Oxygen
  • Nitrogen
  • Solar radiation
  • Consumers
Which ones are reservoirs of phosphorus and nitrogen cycles respectively?
  • Consumers
  • Atmosphere and bedrock
  • Atmosphere and producers
  • Bedrock and atmosphere
Which of the following is not correct?
  • In most ecosystems, the pyramids of numbers and biomass are upright.
  • In tree dominated ecosystem, the pyramid of numbers is inverted.
  • In deep water ecosystem, the pyramid of biomass is upright.
  • Pyramid of energy expresses mainly the rate of food production.
  • Total energy flow at successive trophic levels always decreases.
Highest annual net primary productivity is of
  • Topical deciduous forest
  • Temperate evergreen forest
  • Temperate deciduous forest
  • Tropical rain forest
Ecosystem having the highest primary productivity is
  • Pond
  • Ocean
  • Desert
  • Forest
An ecosystem with little primary productivity is
  • Forest
  • River
  • Sea
  • Grassland
Estuaries are highly productive as they are nutrient trap due to mixing of
  • Ocean and pond
  • Lake and river
  • Pond and lake
  • River and Sea water
Which atom mostly limits the primary productivity? 
  • P
  • O
  • N
  • C
Important steps in decomposition are
  • Fragmentation and mineralisation
  • Leeching and catabolism
  • Humification and mineralisation
  • All the above
Biomass available for consumption by herbivores and decomposers is called
  • Secondary productivity
  • Standing crop
  • Gross primary productivity
  • Net primary productivity
In the pyramid of numbers, find out the correct possibilities.

697309_d2f83737ec2745908ca015792c33f00e.JPG
  • Level PC is rats and level SC is cats
  • Level PP is pipal tree and level SC is sheep
  • Level PP is phytoplankton in sea and level TC is whale
  • Level PC is insects and level SC is small insectivorous birds
The pyramid of biomass in a sea is
  • Upright
  • Slanting
  • Horizontal
  • Inverted
Rate of formation of organic matter by rabbit in a grassland is
  • Gross primary production
  • Net primary production
  • Net productivity
  • Secondary productivity
Which is not a gaseous biogeochemical cycle?
  • Sulphur
  • Phosphorus
  • Nitrogen
  • Carbon
The upright pyramid of number is absent in
  • Lake
  • Forest
  • Grassland
  • Aquatic
Out of nutrient cycles of sulphur (a) phosphorus (b) carbon (c) and nitrogen (d), which one is sedimentary?
  • a only
  • b only
  • c only
  • a and b only
  • c and d only
Which one of the following representations shows the pyramid of numbers in a forest ecosystem?
697314_37f0d0f76ea34e518eb96f272aaaf66d.JPG
  • d
  • a
  • b
  • c
Loss of energy from one trophic level to next higher trophic level is:
  • 30%
  • 40%
  • 60%
  • 90%
An inverted pyramid of number and an inverted pyramid of biomass are respectively seen in
  • Grassland Tree ecosystem
  • Sea and Tree ecosystem
  • Tree and Sea ecosystem
  • Sea and Grassland ecosystem
  • Tree and Grassland ecosystem
Which of the following statements is incorrect?
  • The species that invade a bare area are called pioneer species
  • The entire sequence of communities that successively change in a given area called sere
  • Pyramid of energy is always inverted
  • Pyramid of numbers in a tree ecosystem can be inverted
Select the correct statement.
  • Phosphorus cycle is an example of gaseous nutrient cycle
  • The pyramid of biomass in sea is generally inverted
  • By the process of humification, soluble inorganic nutrients go down into soil horizon
  • A given organism may not occupy more than one trophic level simultaneously
  • Pyramid of energy is always inverted, can never be upright
Which process of decomposition is correctly described?
  • Leaching: Water soluble inorganic nutrients rise to the top layers of soil
  • Fragmentation: Carried out by organisms such as earthworm
  • Humification: Leads to accumulation of a dark coloured substance humus which undergoes microbial action at a very fast rate
  • Catabolism: Last step in decomposition under fully anaerobic conditions
Which is correct about GPP and NPP in a ecosystem?
  • NPP = GPP - Plant respiration
  • NPP = GPP + Plant respiration
  • NPP = GPP - Animal respiration
  • NPP = GPP + Animal respiration
Biomass available for consumers and rate of formation of new organic matter by consumers are
  • Gross primary productivity and net primary productivity
  • Net primary productivity and gross primary productivity
  • Gross primary productivity and secondary productivity
  • Net primary productivity and secondary productivity
  • Secondary productivity and net primary productivity
Gross primary productivity is the rate of production of ____ during photosynthesis.
  • Organic matter
  • Oxygen
  • Carbon dioxide
  • Chlorophyll
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