CBSE Questions for Class 12 Medical Biology Ecosystem Quiz 13 - MCQExams.com

Human activity affecting carbon cycle is
  • Burning of fossil fuels
  • Burning and ploughing of tropical rain forest
  • Growing paddy
  • Both A and B
Pick the correct statement.
  • Home range of members of a species has larger area than that of territory.
  • Many insects mainly honey bees communicate among themselves by secreting pheromones.
  • The last succession in series of biotic succession is called as climax community.
  • Number of individuals of particular species present in a unit area at a given time is known as population size.
In the population having high growth rate, the age pyramid is shown by 
  • Straight pyramid shaped
  • Bell shaped
  • Parabola shaped
  • None of the above
Plagioclimax is climax of plagiosere which means
  • Sere of marine plants
  • Deflected sere resulting in deviation of plant succession from natural course due to human activity
  • Sere where plant succession deviates from its natural course due to human activity
  • Both B and C
Primary succession takes much longer than secondary succession, because it involves
  • Development of the soil
  • Development of a seed bank
  • Colonization by organisms that are farther away
  • Colonization by more K-selected organism
Primary productivity can be measured by
  • Harvest method
  • Chlorophyll content
  • Oxygen given out
  • All of the above
Which region of the sea will have maximum, productivity?
  • Coastal
  • Continental shelf water level
  • Deep sea
  • Very deep sea
The developmental stages in a community are called ______.
  • Climax changes
  • Biological changes
  • Seral changes
  • Climatic changes
Secondary succession can occur on
  • Burnt lands.
  • Lumbered lands.
  • Cut wood lands.
  • All of the above.
In any lithosere, the pioneer community is
  • Blue green algae
  • Foliose lichens
  • Mosses
  • Crustose lichen
The total amount of conversion of light energy into chemical energy of organic molecules in an ecosystem is
  • Net primary productivity
  • Gross primary productivity
  • Gross secondary productivity
  • None of the above
The initial community of the area which is replaced in time by a sequence of succeeding communities is
  • Final stage
  • Climax
  • Pioneer stage
  • None of the above
Succession on secondary bare area is
  • Primosere
  • Xerosere
  • Subsere
  • None of the above
The upright pyramid of number may not be traced in a
  • Lake
  • Grassland
  • Pond
  • Forest tree
In plant succession, when climax is reached the net productivity
  • Continues to increase
  • Becomes halved
  • Becomes stable
  • Becomes zero
  • Becomes 10%
The succession includes in which of the following series?
  • Lichens - mosses - shrubs
  • Lichens - mosses - trees
  • Mosses - trees - shrubs
  • Mosses - lichens - trees
Which of the following always shows steeper slopes?
  • Pyramid of mass
  • Pyramid of number
  • Pyramid of energy
  • Pyramid of energy in the aquatic biomes
The inverted ecological pyramid can be seen in case of
  • Pyramid of numbers in a grassland
  • Pyramid of biomass in a fallow land
  • Pyramid of biomass in a lake
  • Energy pyramid in a spring
Which of the following is expected to have the highest value ($$gm/m^2/yr$$) in a grassland ecosystem?
  • Secondary production
  • Tertiary production
  • Gross production (GP)
  • Net production (NP)
Find out the correct order of succession levels in xerarch.
  • Lichen, moss stage, annual herb stage, perennial herb stage, shrub stage, forest
  • Annual herb stage, perennial herb stage, lichen moss stage, shrub stage, forest
  • Perennial herb stage, annual herb stage, lichen moss stage, shrub stage, forest
  • Shrub stage, forest, annual herb stage, perennial herb stage, lichen moss stage
  • Forest, shrub stage, annual stage, perennial herb stage, lichen moss stage
Most of the plants cultivated in agriculture are actually belonging to the succession level 
  • Early 1$$^{o}$$ succession
  • Late 1$$^{o}$$ succession
  • Early 2$$^{o}$$ succession
  • Late 2$$^{o}$$ succession
In a climax community
  • Size of individual is small
  • Food chain and food web is complex
  • Efficiency of energy use is low
  • Ecological niches are few generalised compared to adjoining communities
Which one of the following statements is correct for secondary succession?
  • It is similar to primary succession except that it has a relatively faster pace.
  • It begins on a bare rock.
  • It occurs on a deforested site.
  • It follows primary succession.
Pyramid of energy is always upright, it represents
  • There is increase in energy of ecosystem.
  • There is decrease in energy due to concentration in successive levels.
  • There is decrease in energy due to loss in form of heat in each trophic level.
  • There is increase in energy due to gain of heat in each trophic level.
Which of the following representation shows the pyramid of numbers in a forest ecosystem?
228392_ef5b7cf4a63f40dfa5c4a7cd57f73aa6.png
  • D
  • A
  • B
  • C
Which one of the following statements for pyramid of energy is incorrect, whereas the remaining three are correct?
  • It is upright in shape.
  • Its base is broad.
  • It shows energy content of different trophic level organisms.
  • It is inverted in shape.
Ecesis is
  • Establishment of a plant in a new place
  • A condition of equilibrium
  • Climax
  • Invasion of a number of plants
Ginkgo has been taken out of the list of endangered species, because it had been conserved by
  • In-situ conservation
  • Ex-situ conservation
  • Imported in large number from Japan
  • None of the above
The biomass available for consumption by the herbivores and the decomposers is called as _______________.
  • Gross primary productivity
  • Net primary productivity
  • Secondary productivity
  • Standing crop
The pyramid of energy in any ecosystem is
  • Always upright 
  • May be upright
  • Always inverted
  • May be inverted
Which one of the following is considered as pioneer community in xerarch?
  • Annual herb
  • Perennial herb
  • Scrub stage
  • Forest stage
  • Lichen
A rocky barren land after some time changes into fertile rich, crop yielding land. Which sequence might have occured?
  • Lichens, mosses, shrubs, herbs
  • Lichens, mosses, herbs, shrubs
  • Mosses, herbs, shrubs, lichens
  • Herbs, shrubs, lichens, mosses
Succession in a water body leads to formation of
  • Mesophytic vegetation
  • Xerophytic vegetation
  • Halophytic vegetation
  • Epiphytic vegetation
The largest vegetational group is known as
  • Ecosystem
  • Association
  • Consociation
  • Formation
The ecological pyramid of numbers in pond ecosystem is
  • Upright
  • Inverted
  • May upright or inverted
  • First upright then inverted
Which ecological pyramid can never occur in an inverted form?
  • Pyramid of number
  • Pyramid of biomass
  • Pyramid of energy
  • Pyramid of species richess
Given below is one of the types of ecological pyramids. This type represents 
236513_fd1a2cf73fec4931ba6badddccf46dd4.png
  • Pyramid of numbers in a grassland
  • Pyramid of biomass in a fallow land
  • Pyramid of biomass in a lake
  • Energy pyramid in a spring
The number of primary producers in a specified area would be maximum in 
  • Pond ecosystem
  • Grassland ecosystem
  • Marine ecosystem
  • Desert ecosystem
In plant succession last community is called as
  • Ecotone
  • Climax community
  • Seral community
  • Ecocystem
The correct sequence of plants in a hydrosere is
  • $$Oak \rightarrow Lantana \rightarrow Volvox \rightarrow Hydrilla \rightarrow Pistia \rightarrow Scirpus $$
  • $$Oak \rightarrow Lantana \rightarrow Scirpus \rightarrow Pistia \rightarrow Hydrilla \rightarrow Volvox$$
  • $$Volvox \rightarrow Hydrilla \rightarrow Pistia \rightarrow Scirpus \rightarrow Lantana \rightarrow Oak$$
  • $$Pistia \rightarrow Volva\rightarrow Scirpus\rightarrow Hydrilla \rightarrow Oak \rightarrow Lantana $$
Which of the following is the most productive ecosystem?
  • Estuary
  • Mountain
  • Desert
  • None of the above
In the phosphorus cycle, weathering makes phophate available first to 
  • Decomposers
  • Consumers
  • Producers
  • All of the above
The rate at which producers in an ecosystem capture and store chemical energy as biomass is called as
  • Gross primary productivity
  • Net primary productivity
  • Net secondary productivity
  • Gross secondary productivity
Match the following and select the correct option.
Column 1
(a) Earthworm
Column 2
(i) Pioneer species
(b) Succession
(ii) Detrivore
(c) Ecosystem service
(iii) Natality
(d) Population growth
(iv) Pollination
  • $$a=(i), b=(ii), c=(iii), d=(iv)$$
  • $$a=(iv), b=(i), c=(iii), d=(ii)$$
  • $$a=(iii), b=(ii), c=(iv), d=(i)$$
  • $$a=(ii), b=(i), c=(iv), d=(iii)$$
Ozone hole was first detected over
  • Arctic circle
  • Antartica
  • Equator
  • All of these
Highest value in g/m$$^2$$/yr of a grassland ecosystem would be
  • Gross primary production
  • Net primary production
  • Secondary production
  • Tertiary productlon
The breakdown of detritus into smaller particles by earthworm is a process called as
  • Humification
  • Fragmentation
  • Mineralisation
  • Catabolism
In parasitic food chain, the pyramid of number is
  • Inverted
  • Upright
  • Linear
  • Upright and inverted
The correct order of succession in xerarch is
  • Annual herb stage--> perennial herb stage--> lichen moss stage--> shrub stage--> forest
  • Perennial herb stage--> annual herb stage--> lichen moss stage--> shrub stage--> forest
  • Lichen moss stage--> annual herb stage--> perennial herb stage--> shrub stage--> forest
  • Shrub stage--> forest--> annual herb stage--> perennial herb stage--> lichen moss stage
The ultimate source of energy in an ecosystem is
  • glucose
  • sucrose
  • sunlight
  • green plants
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