CBSE Questions for Class 12 Medical Biology Ecosystem Quiz 1 - MCQExams.com

In an ecosystem, the rate of production of organic matter during photosynthesis is termed as
  • Secondary productivity.
  • Net productivity.
  • Net primary productivity.
  • Gross primary productivity.
Given above is a simplified model of phosphorus cycling in a terrestrial ecosystem with four blanks (A-D). Identify the blanks.

312232.png
  • A- Rock minerals, B- Detritus, C- Litter falls, D- Producers
  • A- Litter, B- Producers, C- Rock minerals, D- Detritus
  • A- Detritus, B- Rock minerals, C- Producers, D- Litter fall
  • A- Producers, B- Litter fall, C- Rock minerals, D- Detritus
Secondary succession takes place on/in
  • Newly created pond.
  • Newly cooled lava.
  • Bare rock.
  • Degraded forest.
In relation to Gross primary productivity and Net primary productivity of an ecosystem, which one of the following statements is correct?
  • Gross primary productivity is always more than Net primary productivity.
  • Gross primary productivity and Net primary productivity are one and the same.
  • There is no relationship between Gross primary productivity and Net primary productivity.
  • Gross primary productivity is always less than Net primary productivity.
The rate of formation of new organic matter by rabbit in a grassland is called
  • Secondary productivity
  • Net primary productivity
  • Grass primary productivity
  • None of the above
In which of the following, both pairs have correct combination?
  • Gaseous nutrient cycle-Sulphur and Phosphorus, Sedimentary nutrient cycle-Carbon and Nitrogen
  • Gaseous nutrient cycle-Sulphur and Phosphorus, Sedimentary nutrient cycle-Carbon and sulphur
  • Gaseous nutrient cycle-Carbon and sulphur, Sedimentary nutrient cycle-Nitrogen and sulphur
  • Gaseous nutrient cycle-Carbon and nitrogen, Sedimentary nutrient cycle- Sulphur and Phosphorus
Which of the following representations shows the pyramid of number in a forest ecosystem?
306739_7f868dc481034601b19f6c1c1bdf17a3.png
  • C
  • D
  • A
  • B
Which of the following ecological pyramids is generally inverted?
  • Pyramid of numbers in grassland
  • Pyramid of energy
  • Pyramid of biomass in a forest
  • Pyramid of biomass in a sea
The second stage of hydrosere is occupied by plants like
  • Typha
  • Salix
  • Vallisneria
  • Azolla
During ecological succession
  • The changes lead to a community that is in near equilibrium with the environment and is called pioneer community.
  • The gradual and predictable change in species composition occurs in a given area.
  • The establishment of a new biotic community is very fast in its primary phase.
  • The numbers and types of animals remain constant.
Given image is one of the types of ecological pyramids. This type represents
430986.png
  • Pyramid of numbers in a grassland
  • Pyramid of biomass in a fallow land
  • Inverted pyramid of biomass in a lake
  • Energy pyramid in a spring
Keystone species deserve protection because they
  • Are capable of surviving in harsh environmental conditions.
  • Indicate presence of certain minerals in the soil.
  • Have become rare due to overexploitation.
  • Play an important role in supporting other species.
Biotic succession is caused by
  • Competition among species
  • Occurrence of dieseases
  • Changes in grazing habits
  • Adaptive ability to environmental changes
Cycling of elements in an ecosystem is called as
  • Chemical cycle
  • Geochemical cycle
  • Biogeochemical cycle
  • Geological cycle
In forest ecosystem, pyramid of number is
  • Upright
  • Inverted
  • Any of the two
  • None of the above
Which one of the following is not a gaseous biogeochemical cycle in ecosystem?
  • Sulphur cycle
  • Phosphorus cycle
  • Nitrogen cycle
  • Carbon cycle
The reservoir pool for gaseous cycles of matter is
  • Atmosphere
  • Hydrosphere
  • Both (A) and (B)
  • Lithosphere
Which one of the following ecosystem types has the highest annual net primary productivity?
  • Tropical rain forest
  • Tropical deciduous forest
  • Temperate evergreen forest
  • Temperate deciduous forest
Which is an example of true pyramid in an ecosystem?
  • Pyramid of biomass
  • Pyramid of number
  • Pyramid of energy
  • None of the above
Which of the following food chains directly depend on solar radiations?
  • Predator
  • Grazing
  • Detritus
  • None of these
A community which starts succession in a habitat is 
  • Pioneer Community
  • Seral Community
  • Biotic Community
  • Ecosere
In an ecosystem
  • Cycling of energy and nutrients is a coupled process.
  • Cycling of energy is an independent process.
  • Movement of energy is unidirectional.
  • Movement of energy is bidirectional.
The difference between primary succession and secondary succession is that
  • Primary succession occurs on soil
  • Primary succession begins with lichens
  • Primary succession begins with plant species
  • Secondary succession involves animal species
  • Secondary succession involves the weathering of rock
Which of these help in decomposition of organic wastes?
  • Bacteria
  • Fungi
  • Earthworm
  • All of the above
The largest biomass in food chain is present in 
  • Plants
  • Grasshopper
  • Mouse
  • Owl
  • Snake
The rate at which light energy is converted into chemical energy of organic molecules is 
  • Net primary productivity
  • Gross secondary productivity
  • Net secondary productivity
  • Gross primary productivity
Which of these is a biogeochemical cycle?
  • Water cycle
  • Nitrogen cycle
  • Carbon cycle
  • All of the above
Which of the following are the examples of biogeochemical cycle?
  • Nitrogen cycle
  • Krebs cycle
  • Electron cycle
  • All of the above
.......... play a very important role in  decomposition of organic matter in the soil
  • Cat
  • Plants
  • Microorganisms
  • All of the above
The given pyramid of biomass represents different trophic levels in a terrestrial ecosystem. The producers are represented by level
497066.jpg
  • 1
  • 2
  • 3
  • 4
  • 5
Which of the following is the largest reservoir of carbon?
  • Soil
  • Atmosphere
  • Ocean
  • Sedimentary rocks
A progressive series of changes in plant and animal life in an area from initial colonisation is called
  • Evolution
  • Succession
  • Selection
  • Specilisation
Rate of storage of organic matter not used by heterotrophs is termed as
  • Net productivity
  • Net primary productivity
  • Gross primary productivity
  • Secondary productivity
Graphic representation of biomass relationship between the producers and consumers in an ecosystem is called
  • Trophic level
  • Ecological system
  • Ecological niche
  • Ecological pyramid
Reservior of sulphur is
  • Rocks
  • Oceans
  • Atmosphere
  • Lakes
Energy stored at the consumer level is 
  • Gross primary productivity
  • Net primary productivity
  • Net productivity
  • Secondary productivity
Which one is a sedimentary cycle?
  • Oxygen cycle
  • Nitrogen cycle
  • Hydrogen cycle
  • Phosphorus cycle
  • Carbon cycle
Succession showing changes in communities at a place is called 
  • Geographical succession
  • Biotic succession
  • Physiographic succession
  • Climatic succession
In pyramid of food, the producers occupy
  • The base
  • Position near the base
  • Apex
  • Position near apex
Pyramid of numbers in a grassland/true ecosystem is
  • Always inverted
  • Always upright
  • Both A and B
  • Spindle shaped
Breakdown of detritus into smaller particles by earthworm is a process called
  • Humification
  • Fragmentation
  • Mineralisation
  • Catabolism
In ecosystem, cycling of nutrients is called
  • Geological cycle
  • Biogeochemical cycle
  • Geochemical cycle
  • Chemical cycle
The decomposed organic matter is called
  • Callose
  • Callus
  • Litter
  • Humus
The process of breakdown of detritus by detrivores is
  • Mineralisation
  • Fragmentation
  • Leaching
  • Humification
Breakdown of detritus into small particles by detrivores is called
  • Leaching
  • Humification
  • Catabolism
  • Mineralisation
  • Fragmentation
Rate of conversion of light energy into chemical energy of organic molecules in an ecosystem is
  • Gross primary productivity
  • Net primary productivity
  • Net secondary productivity
  • Gross secondary productivity
The animal species controlling ecosystem functioning is known as 
  • Edge species
  • Pioneer species
  • Keystone species
  • Umbrella species
Total energy fixed by an ecosystem is
  • Primary production
  • Gross production
  • Net production
  • Secondary production
Which one statement for pyramid of energy is incorrect?
  • Inverted in shape
  • Upright in shape
  • Base is broad
  • Shows energy content of different trophic levels
Occurrence of relatively definite sequence of communities over a period of time in the same area is known as 
  • Change in biodiversity
  • Ecosystem degradation
  • Ecological succession
  • Economic succession
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