CBSE Questions for Class 12 Medical Biology Ecosystem Quiz 4 - MCQExams.com

The following ecological pyramids represent the number of organisms involved in feeding relationships.

Choose the LETTER (A, B, C or D) which is most likely to represent the organisms in each of the figures.

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The phosphorus cycle differs from those of carbon and nitrogen as well as those of sulphur, oxygen and hydrogen in that it lacks 
  • Water
  • Dust particles
  • Gaesous phase
  • All of the above
Pyramid of energy in a forest ecosystem is
  • Always inverted
  • Always upright
  • Both upright and inverted depending on ecosystem
  • First upright the inverted
Natural reservoir of phosphorus is 
  • Animal bones
  • Rock
  • Fossils
  • Sea water
Secondary productivity is 
  • Conversion of physical energy into chemical energy at producer level
  • Conversion of physical energy into chemical energy at consumer level
  • The rate of energy storage at consumer level
  • The decomposition of organic matter by decomposers
Cycling of elements in any ecosystem is called as
  • Chemical cycle
  • Geochemical cycle
  • Biogeochemical cycle
  • Geological cycle
The utilization of elements and compounds in nature and their subsequent return to the environment is called
  • Life cycles
  • Cyclic pathway
  • Material cycles
  • Recycling
Biogeochemical cycling means cycling of 
  • Energy in ecosystem
  • Gases between plants and the atmosphere
  • Nutrients in an ecosystem
  • None of the above
The percentage of solar radiation absorbed by all the green plants for the process of photosynthesis is about:
  • 1 %
  • 5 %
  • 8 %
  • 10 %
Which one of the following atoms often limit the primary productivity of an ecosystem? 
  • Carbon
  • Nitrogen
  • Phosphorus
  • Sulphur
In an ecosystem, the population of
  • Primary producers is larger than primary consumers.
  • Secondary consumers is largest.
  • Primary consumers out numbers primary producers.
  • Primary consumers are least dependent upon primary producers.
Which one of these is a sedimentary cycle?
  • Phosphorous
  • Hydrogen
  • Oxygen
  • Nitrogen
Which of the following is formed by producers in ecosystem?
  • Net primary productivity
  • Gross primary productivity
  • Net secondary productivity
  • Primary productivity
Select the correct matched ones.
A. Sedimentary nutrient- Nitrogen cycle
B. Pioneer species- Lichens 
C. Secondary succession- Burned forests
D. Pyramid of biomass in sea- Upright 
  • A, B and D only
  • A and C only
  • B and C only
  • B and D only
The graphic representation of trophic level is represented by a pyramid. Which of the following pyramid is always a true pyramid unlike the others?
  • Pyramid of number
  • Pyramid of biomass
  • Pyramid of energy
  • Both a and c
Which one of the following is sedimentary cycle? 
  • Carbon
  • Hydrogen
  • Nitrogen
  • Phosphorus
The efficiency of any ecosystem is best depicted by pyramid of  
  • Energy
  • Number
  • Biomass
  • Volume
Plant succession is a ............. process.
  • Definite
  • Haphazard
  • Unimportant
  • Harmful
Biogeochemical cycle of which element has atmospheric phase?
  • Carbon
  • Sodium
  • Phosphorus
  • Magnesium
One of Eltonian pyramids have to be upright always. That is, pyramid of
  • Biomass
  • Energy
  • Number
  • All of the above
The productivity of all the autotrophs including green plants, protists and bacteria is called as
  • Secondary productivity
  • Primary productivity
  • NPP
  • GPP
When ecological succession begins, the dominating species are:
  • Pioneer species
  • Keystone species
  • Climax species
  • Invader species
The rate of formation of new organic matter by rabbit in a grassland,
is called as
  • Net productivity
  • Secondary productivity
  • Net primary productivity
  • Gross primary productivity
Plant community development is termed as
  • Corrosion
  • Erosion
  • Succession
  • Possesion
Biomass of producers within a specified area will be maximum in 
  • Forest ecosystem
  • Grassland ecosystem
  • Both A and B
  • Lake ecosystem
The final stable community in ecological succession is termed as
  • Pioneers
  • Sere
  • Climax community
  • Carnivores
Serule is
  • Hydrosere
  • Biosere
  • Microbial succession
  • Lithosere
The natural process by which different groups or communities colonize the same area over a period of time in a definite sequence is called:
  • Adaptation
  • Variation
  • Succession
  • Biological rhythm
What is represented by the following sequence? 

Cyanobacteria, Crustose lichens, Foliose lichens, Mosses, Shrub, Dicotyledenous plants.
  • Genetic drift
  • Eltonian pyramid
  • Ecological succesion
  • Phylogenetic relationship
In the pyramid of numbers, for a grassland ecosystem, the largest population is that of
  • Producers
  • Tertiary consumers
  • Secondary consumers
  • Primary consumers
  • Herbivores
The storage of energy at consumer level is known as
  • Gross primary production
  • Secondary productivity
  • Net primary productivity
  • Net productivity
The flow of materials from non living components to living components and back to the non living components in a more or less cyclic manner is called 
  • Gaseous cycle
  • Sedimentary cycle
  • Biogeochemical cycle
  • Hydrologic cycle
The community which starts succession at a place is termed as
  • Climax community
  • Seral community
  • Pioneer community
  • Primary community
Pyramids of energy are 
  • Always upright
  • Always inverted
  • Mostly upright
  • Mostly inverted
In any given ecosystem, number of individuals in a species remains more or less constant over a period of time. This constancy of number is maintained by
  • Parasites
  • Predators
  • Man
  • Available food
  • All of the above
Stable plant community formed during succession is called as
  • Sere community
  • Climax community
  • Dominant community
  • Ecotone
Earliest settlers on barren lands or the 'farmers of nature' are
  • Diatoms
  • Lichens
  • Moss and grasses
  • Ferns
Gross primary productivity is 
  • Rate at which organic molecules are formed in an autotroph
  • Rate at which organic molecules are used up by an autotroph
  • Storage of organic molecules in the body of an autotroph
  • Rate at which organic molecules are transferred to next higher trophic level
The pyramid of numbers in grassland ecosystem will be  ?
  • Upright
  • Inverted
  • Irregular
  • Linear
In plant succession, last community is called as
  • Ecotone
  • Climax community 
  • Seral community
  • Ecosystem
Pyramid of energy in a forest ecosystem is 
  • Always inverted
  • Always upright
  • Both upright and inverted depending on ecosystem
  • First upright then inverted
Total amount of energy trapped by green plants in food is called ____.
  • Gross primary production
  • Net primary production
  • Standing crop
  • Standing state
The number of individuals of a species in a particular ecosystem at a given time remains constant due to
  • Man
  • Parasites
  • Predators
  • Available food
Concept of ecological pyramid is given by 
  • Odum
  • Elton
  • Darwin
  • Reiter
_________ are the cyclic pathways through which chemical elements move from environment to organism and back to the environment.
  • Biogeochemical cycles
  • Geo-chemical cycles
  • Physio-chemical cycles
  • All of the above
In order to maintain proper ecological balance  
  • The existing forests would be cleared and new ones should be planted
  • Some quick growing annuals should be planted if a tree must be cut for other uses
  • Tree must be cut whenever necessary because the underground part performs the useful purpose
  • A tree should be planted in place of one to be cut
In which layer of atmosphere ozone is maximum concentrated?
  • Troposphere
  • Stratosphere
  • Mesosphere
  • Ionosphere
Maximum photosynthesis takes place by 
  • Phytoplankton
  • Zooplankton
  • Marsh plants
  • Woody plants
A decrease in the grass population will most immediately decrease the available energy for the:
  • Mouse
  • Snake
  • Hawk
  • Frog
The percentage of solar radiation absorbed by all the green plants for the process of photosynthesis is about 
  • 1%
  • 5%
  • 8%
  • 10%
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