ECOSYSTEM

Q1. An ecosystem can be visualised as a functional unit of nature where living organisms interact among themselves and also with the surrounding physical environment.
(A) True statement as per the chapter
(B) False because ecosystems have no interaction with physical environment
(C) False because it is only a collection of abiotic components
(D) False because it is a man-made artificial system only
Ans: A

Q2. Ecosystems vary greatly in size from a small pond to a large forest or a sea.
(A) Correct as per the description of ecosystem size variation
(B) Incorrect because all ecosystems are of same size
(C) Incorrect because ecosystems do not vary in size
(D) Incorrect because size variation is only between pond and lake
Ans: A

Q3. Many ecologists regard the entire biosphere as a global ecosystem, as a composite of all local ecosystems on Earth.
(A) True as stated in the chapter
(B) False because biosphere is not considered an ecosystem
(C) False because biosphere is only a terrestrial ecosystem
(D) False because biosphere has no relation with local ecosystems
Ans: A

Q4. Which of the following are examples of terrestrial ecosystems?
(A) Forest, grassland and desert
(B) Pond, lake, wetland, river and estuary
(C) Crop fields and aquarium only
(D) Biosphere as a single unit
Ans: A

Q5. Which of the following are examples of aquatic ecosystems?
(A) Pond, lake, wetland, river and estuary
(B) Forest, grassland and desert
(C) Crop fields and aquarium
(D) Only man-made systems
Ans: A

Q6. Crop fields and an aquarium may also be considered as
(A) Man-made ecosystems
(B) Natural terrestrial ecosystems
(C) Natural aquatic ecosystems only
(D) Global ecosystems
Ans: A

Q7. It is convenient to divide ecosystems into two basic categories namely
(A) Terrestrial and aquatic
(B) Natural and artificial only
(C) Small and large sized only
(D) Biotic and abiotic components
Ans: A

Q8. Identification and enumeration of plant and animal species of an ecosystem gives its
(A) Species composition
(B) Stratification
(C) Primary productivity
(D) Nutrient cycling
Ans: A

Q9. Vertical distribution of different species occupying different levels is called
(A) Stratification
(B) Species composition
(C) Decomposition
(D) Energy flow
Ans: A

Q10. In a forest ecosystem, trees occupy the top vertical strata, shrubs the second and herbs and grasses occupy the bottom layers. This pattern is an example of
(A) Stratification
(B) Species composition only
(C) Primary production
(D) Mineralisation
Ans: A

Q11. The components of the ecosystem are seen to function as a unit when we consider
(A) Productivity, Decomposition, Energy flow and Nutrient cycling
(B) Only species composition and stratification
(C) Only size and location of ecosystem
(D) Only abiotic factors
Ans: A

Q12. To understand the ethos of an aquatic ecosystem, a small pond is taken as an example because
(A) It is a fairly self-sustainable unit and rather simple example that explains even the complex interactions
(B) It is the largest ecosystem on Earth
(C) It has no decomposers
(D) It has only abiotic components
Ans: A

Q13. In a pond ecosystem, the abiotic component consists of
(A) Water with all the dissolved inorganic and organic substances and the rich soil deposit at the bottom of the pond
(B) Only the fish and other animals
(C) Only the phytoplankton and algae
(D) Only the bacteria and fungi
Ans: A

Q14. The solar input, the cycle of temperature, day-length and other climatic conditions in a pond
(A) Regulate the rate of function of the entire pond
(B) Have no effect on pond functioning
(C) Only affect the fish population
(D) Only control the water level
Ans: A

Q15. The autotrophic components of a pond ecosystem include
(A) Phytoplankton, some algae and the floating, submerged and marginal plants found at the edges
(B) Only zooplankton and bottom dwelling forms
(C) Only fungi and bacteria
(D) Only flagellates
Ans: A

Q16. The consumers in a pond ecosystem are represented by
(A) Zooplankton, the free swimming and bottom dwelling forms
(B) Only phytoplankton and algae
(C) Only fungi and bacteria
(D) Only marginal plants
Ans: A

Q17. The decomposers in a pond ecosystem are
(A) Fungi, bacteria and flagellates especially abundant in the bottom of the pond
(B) Only fish and other consumers
(C) Only phytoplankton
(D) Only floating plants
Ans: A

Q18. The pond ecosystem performs the function of conversion of inorganic into organic material with the help of the radiant energy of the sun by the autotrophs.
(A) True as described
(B) False because autotrophs cannot convert inorganic to organic
(C) False because only consumers perform this function
(D) False because sun energy is not involved
Ans: A

Q19. In the pond ecosystem, consumption of the autotrophs by heterotrophs and decomposition and mineralisation of the dead matter to release them back for reuse by the autotrophs
(A) Are repeated over and over again
(B) Happen only once in the lifetime of the pond
(C) Do not occur at all
(D) Occur only in terrestrial ecosystems
Ans: A

Q20. In an ecosystem like the pond, there is
(A) Unidirectional movement of energy towards the higher trophic levels and its dissipation and loss as heat to the environment
(B) Bidirectional movement of energy with no loss
(C) Only cyclic movement of energy among producers
(D) No movement of energy at all
Ans: A

Q21. A constant input of solar energy is the basic requirement for any ecosystem to function and sustain.
(A) True as stated
(B) False because ecosystems can function without solar energy
(C) False because only nutrient input is required
(D) False because only water input is required
Ans: A

Q22. Primary production is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis.
(A) True as per definition
(B) False because it is produced by consumers
(C) False because it is measured only in energy units
(D) False because time period is not considered
Ans: A

Q23. Primary production is expressed in terms of
(A) Weight (gm⁻²) or energy (kcal m⁻²)
(B) Only number of organisms
(C) Only volume of water
(D) Only height of plants
Ans: A

Q24. The rate of biomass production is called
(A) Productivity
(B) Decomposition
(C) Stratification
(D) Mineralisation
Ans: A

Q25. Productivity is expressed in terms of
(A) gm⁻² yr⁻¹ or (kcal m⁻²) yr⁻¹
(B) Only gm⁻²
(C) Only kcal m⁻²
(D) Only number per year
Ans: A

Q26. Gross primary productivity (GPP) of an ecosystem is
(A) The rate of production of organic matter during photosynthesis
(B) The rate of consumption by herbivores
(C) The rate of decomposition by bacteria
(D) The rate of nutrient leaching
Ans: A

Q27. A considerable amount of GPP is utilised by plants in
(A) Respiration
(B) Decomposition
(C) Leaching
(D) Fragmentation
Ans: A

Q28. Gross primary productivity minus respiration losses (R) is the
(A) Net primary productivity (NPP)
(B) Secondary productivity
(C) Gross secondary productivity
(D) Standing crop
Ans: A

Q29. The formula for net primary productivity is
(A) GPP – R = NPP
(B) NPP – R = GPP
(C) GPP + R = NPP
(D) NPP + R = GPP
Ans: A

Q30. Net primary productivity is the available biomass for the consumption to
(A) Heterotrophs (herbivores and decomposers)
(B) Only autotrophs
(C) Only producers
(D) Only abiotic components
Ans: A

Q31. Secondary productivity is defined as
(A) The rate of formation of new organic matter by consumers
(B) The rate of production by plants during photosynthesis
(C) The rate of decomposition of detritus
(D) The rate of nutrient mineralisation
Ans: A

Q32. Primary productivity depends on
(A) The plant species inhabiting a particular area, environmental factors, availability of nutrients and photosynthetic capacity of plants
(B) Only the size of the ecosystem
(C) Only the number of consumers
(D) Only the depth of soil
Ans: A

Q33. Primary productivity varies in
(A) Different types of ecosystems
(B) Only aquatic ecosystems
(C) Only terrestrial ecosystems
(D) Only man-made ecosystems
Ans: A

Q34. The annual net primary productivity of the whole biosphere is approximately
(A) 170 billion tons (dry weight) of organic matter
(B) 55 billion tons
(C) 100 billion tons
(D) 200 billion tons
Ans: A

Q35. Despite occupying about 70 per cent of the surface, the productivity of the oceans is only
(A) 55 billion tons
(B) 170 billion tons
(C) 100 billion tons
(D) 20 billion tons
Ans: A

Q36. Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal matter, constitute
(A) Detritus
(B) Humus
(C) Mineral salts
(D) Standing crop
Ans: A

Q37. The process of breakdown of complex organic matter into inorganic substances like carbon dioxide, water and nutrients is called
(A) Decomposition
(B) Photosynthesis
(C) Stratification
(D) Primary production
Ans: A

Q38. Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called
(A) Fragmentation
(B) Leaching
(C) Catabolism
(D) Humification
Ans: A

Q39. By the process of leaching
(A) Water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts
(B) Complex organic matter is broken into smaller particles
(C) Bacterial enzymes degrade detritus into simpler substances
(D) Dark coloured humus is formed
Ans: A

Q40. Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called
(A) Catabolism
(B) Fragmentation
(C) Leaching
(D) Mineralisation
Ans: A

Q41. Humification leads to accumulation of a dark coloured amorphous substance called
(A) Humus
(B) Detritus
(C) Litter
(D) Mineral salts
Ans: A

Q42. Humus is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. Being colloidal in nature it serves as
(A) A reservoir of nutrients
(B) A source of only carbon dioxide
(C) A source of only water
(D) An energy source for producers directly
Ans: A

Q43. The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as
(A) Mineralisation
(B) Humification
(C) Fragmentation
(D) Leaching
Ans: A

Q44. Decomposition is largely
(A) An oxygen-requiring process
(B) An anaerobic process only
(C) A process that does not require any energy
(D) A process that occurs only at night
Ans: A

Q45. The rate of decomposition is controlled by
(A) Chemical composition of detritus and climatic factors
(B) Only the size of detritus
(C) Only the colour of detritus
(D) Only the location of ecosystem
Ans: A

Q46. In a particular climatic condition, decomposition rate is slower if detritus is rich in
(A) Lignin and chitin
(B) Nitrogen and water-soluble substances like sugars
(C) Only water
(D) Only minerals
Ans: A

Q47. Decomposition rate is quicker if detritus is rich in
(A) Nitrogen and water-soluble substances like sugars
(B) Lignin and chitin
(C) Only complex proteins
(D) Only fats
Ans: A

Q48. Temperature and soil moisture are the most important climatic factors that regulate decomposition through their effects on the activities of
(A) Soil microbes
(B) Only plants
(C) Only animals
(D) Only consumers
Ans: A

Q49. Warm and moist environment
(A) Favour decomposition
(B) Inhibit decomposition
(C) Have no effect on decomposition
(D) Only favour photosynthesis
Ans: A

Q50. Low temperature and anaerobiosis
(A) Inhibit decomposition resulting in build up of organic materials
(B) Favour rapid decomposition
(C) Have no effect on decomposition rate
(D) Only affect producers
Ans: A

Q51. Except for the deep sea hydro-thermal ecosystem, sun is the only source of energy for all ecosystems on Earth.
(A) True as stated
(B) False because all ecosystems have internal energy source
(C) False because only aquatic ecosystems need sun
(D) False because terrestrial ecosystems do not need sun
Ans: A

Q52. Of the incident solar radiation less than 50 per cent of it is
(A) Photosynthetically active radiation (PAR)
(B) Infrared radiation only
(C) Ultraviolet radiation only
(D) Heat energy only
Ans: A

Q53. Plants and photosynthetic bacteria (autotrophs) fix Sun’s radiant energy to make food from simple inorganic materials. Plants capture only
(A) 2-10 per cent of the PAR
(B) 50 per cent of the PAR
(C) 100 per cent of the PAR
(D) 1 per cent of total solar radiation
Ans: A

Q54. The small amount of energy captured by plants (2-10 per cent of PAR)
(A) Sustains the entire living world
(B) Is used only by plants
(C) Is lost completely as heat
(D) Is not used by any organism
Ans: A

Q55. There is unidirectional flow of energy from the sun to producers and then to consumers. This is in keeping with
(A) The first law of thermodynamics
(B) The second law of thermodynamics only
(C) Both laws equally
(D) Neither law
Ans: A

Q56. Ecosystems are not exempt from the Second Law of thermodynamics. They need a constant supply of energy to
(A) Synthesise the molecules they require, to counteract the universal tendency toward increasing disorderliness
(B) Only increase disorder
(C) Only decrease energy
(D) Only store energy without use
Ans: A

Q57. The green plants in the ecosystem are called
(A) Producers
(B) Consumers
(C) Decomposers
(D) Detritivores
Ans: A

Q58. In a terrestrial ecosystem, major producers are
(A) Herbaceous and woody plants
(B) Only phytoplankton
(C) Only algae
(D) Only bacteria
Ans: A

Q59. In an aquatic ecosystem, producers are
(A) Various species like phytoplankton, algae and higher plants
(B) Only herbaceous plants
(C) Only woody plants
(D) Only detritivores
Ans: A

Q60. All organisms are dependent for their food on producers, either directly or indirectly. They are called
(A) Consumers and also heterotrophs
(B) Producers
(C) Autotrophs
(D) Saprotrophs only
Ans: A

Q61. If animals feed on the producers (the plants), they are called
(A) Primary consumers or herbivores
(B) Secondary consumers
(C) Tertiary consumers
(D) Decomposers
Ans: A

Q62. Common herbivores in terrestrial ecosystem are
(A) Insects, birds and mammals
(B) Only fish
(C) Only molluscs
(D) Only bacteria
Ans: A

Q63. Common herbivores in aquatic ecosystem are
(A) Molluscs
(B) Insects and birds only
(C) Mammals only
(D) Fungi
Ans: A

Q64. The consumers that feed on herbivores are
(A) Carnivores or primary carnivores (secondary consumers)
(B) Producers
(C) Decomposers only
(D) Autotrophs
Ans: A

Q65. Those animals that depend on the primary carnivores for food are labelled
(A) Secondary carnivores or tertiary consumers
(B) Primary consumers
(C) Herbivores
(D) Producers
Ans: A

Q66. A simple grazing food chain (GFC) is
(A) Grass (Producer) → Goat (Primary Consumer) → Man (Secondary consumer)
(B) Grass → Man → Goat
(C) Goat → Grass → Man
(D) Man → Goat → Grass
Ans: A

Q67. The detritus food chain (DFC) begins with
(A) Dead organic matter (detritus)
(B) Living green plants
(C) Only consumers
(D) Only sunlight
Ans: A

Q68. Decomposers in detritus food chain are heterotrophic organisms, mainly
(A) Fungi and bacteria
(B) Only plants
(C) Only animals
(D) Only fish
Ans: A

Q69. Decomposers are also known as
(A) Saprotrophs
(B) Autotrophs
(C) Herbivores
(D) Carnivores
Ans: A

Q70. In an aquatic ecosystem, GFC is
(A) The major conduit for energy flow
(B) The minor conduit for energy flow
(C) Not present at all
(D) Equal to DFC in energy flow
Ans: A

Q71. In a terrestrial ecosystem, a much larger fraction of energy flows through
(A) The detritus food chain than through the GFC
(B) The grazing food chain than DFC
(C) Only the producers
(D) Only the consumers
Ans: A

Q72. Detritus food chain may be connected with the grazing food chain at some levels because
(A) Some of the organisms of DFC are prey to the GFC animals
(B) There is no connection possible
(C) Only producers connect them
(D) Only sunlight connects them
Ans: A

Q73. In a natural ecosystem, some animals like cockroaches, crows, etc., are
(A) Omnivores
(B) Only herbivores
(C) Only carnivores
(D) Only producers
Ans: A

Q74. The natural interconnection of food chains make it a
(A) Food web
(B) Single food chain only
(C) Trophic level
(D) Standing crop
Ans: A

Q75. Organisms occupy a specific place in the food chain that is known as their
(A) Trophic level
(B) Species composition
(C) Stratification
(D) Standing crop
Ans: A

Q76. Producers belong to the
(A) First trophic level
(B) Second trophic level
(C) Third trophic level
(D) Fourth trophic level
Ans: A

Q77. Herbivores (primary consumers) belong to the
(A) Second trophic level
(B) First trophic level
(C) Third trophic level
(D) Fourth trophic level
Ans: A

Q78. Carnivores (secondary consumers) belong to the
(A) Third trophic level
(B) First trophic level
(C) Second trophic level
(D) Fourth trophic level
Ans: A

Q79. Each trophic level has a certain mass of living material at a particular time called as the
(A) Standing crop
(B) Net primary productivity
(C) Gross primary productivity
(D) Detritus
Ans: A

Q80. The standing crop is measured as the mass of living organisms (biomass) or the number in a unit area.
(A) True as stated
(B) False because it is measured only in energy units
(C) False because it is measured only as volume
(D) False because it does not include living organisms
Ans: A

Q81. The biomass of a species is expressed in terms of
(A) Fresh or dry weight
(B) Only fresh weight
(C) Only number of individuals
(D) Only energy content
Ans: A

Q82. Measurement of biomass in terms of dry weight is more accurate.
(A) True as stated in the chapter
(B) False because fresh weight is more accurate
(C) False because both are equally accurate
(D) False because biomass cannot be measured
Ans: A

Q83. The number of trophic levels in the grazing food chain is restricted as the transfer of energy follows
(A) 10 per cent law – only 10 per cent of the energy is transferred to each trophic level from the lower trophic level
(B) 50 per cent law
(C) 100 per cent transfer with no loss
(D) 2-10 per cent law only for PAR
Ans: A

Q84. In nature, it is possible to have so many levels in the grazing food chain such as
(A) Producer, herbivore, primary carnivore, secondary carnivore
(B) Only producer and herbivore
(C) Only decomposers
(D) Only consumers
Ans: A

Q85. The detritus food chain
(A) May or may not have the same limitation of trophic levels as GFC (as posed as question in text)
(B) Always has exactly 4 trophic levels
(C) Has no decomposers
(D) Has only producers
Ans: A

Q86. Ecological pyramids express the food or energy relationship between organisms at different trophic levels in terms of
(A) Number, biomass or energy
(B) Only number
(C) Only biomass
(D) Only energy
Ans: A

Q87. The base of each ecological pyramid represents the
(A) Producers or the first trophic level
(B) Tertiary consumers
(C) Decomposers
(D) Top carnivores
Ans: A

Q88. The apex of each ecological pyramid represents the
(A) Tertiary or top level consumer
(B) Producers
(C) First trophic level
(D) Detritus
Ans: A

Q89. The three types of ecological pyramids that are usually studied are
(A) Pyramid of number, pyramid of biomass and pyramid of energy
(B) Only pyramid of number
(C) Only pyramid of biomass
(D) Only pyramid of energy
Ans: A

Q90. In most ecosystems, all the pyramids of number, of energy and biomass are
(A) Upright
(B) Inverted
(C) Spindle shaped
(D) Circular
Ans: A

Q91. In most ecosystems, producers are more in number and biomass than the herbivores, and herbivores are more in number and biomass than the carnivores.
(A) True as generalisation
(B) False because carnivores are always more
(C) False because producers are always less
(D) False because all are equal
Ans: A

Q92. Also energy at a lower trophic level is always
(A) More than at a higher level
(B) Less than at a higher level
(C) Equal to higher level
(D) Not related to higher level
Ans: A

Q93. Pyramid of energy is always upright, can never be inverted, because
(A) When energy flows from a particular trophic level to the next trophic level, some energy is always lost as heat at each step
(B) Energy is created at each level
(C) Energy is cycled back fully
(D) No energy loss occurs
Ans: A

Q94. Each bar in the energy pyramid indicates
(A) The amount of energy present at each trophic level in a given time or annually per unit area
(B) Only the number of organisms
(C) Only the biomass
(D) Only the volume of water
Ans: A

Q95. In a grassland ecosystem, the pyramid of numbers shows
(A) Only three top-carnivores are supported based on production of nearly 6 millions plants
(B) Millions of top carnivores
(C) Equal number at all levels
(D) Inverted shape always
Ans: A

Q96. The pyramid of biomass in sea is generally inverted because
(A) The biomass of fishes far exceeds that of phytoplankton
(B) Phytoplankton biomass is always higher
(C) There are no fishes in sea
(D) Energy is not lost
Ans: A

Q97. Pyramid of biomass shows a sharp decrease in biomass at higher trophic levels in most cases.
(A) True
(B) False because biomass increases at higher levels
(C) False because biomass remains constant
(D) False because only energy pyramid shows decrease
Ans: A

Q98. An inverted pyramid of biomass is seen where small standing crop of phytoplankton supports large standing crop of zooplankton.
(A) True as example given
(B) False because phytoplankton always has higher biomass
(C) False because zooplankton cannot have biomass
(D) False because sea has no pyramid
Ans: A

Q99. Any calculations of energy content, biomass or numbers in pyramids has to include
(A) All organisms at that trophic level
(B) Only a few selected individuals
(C) Only producers
(D) Only top consumers
Ans: A

Q100. A given organism may occupy more than one trophic level simultaneously. For example, a sparrow is a primary consumer when it eats seeds, fruits, peas, and a secondary consumer when it eats insects and worms.
(A) True as stated
(B) False because one organism occupies only one trophic level
(C) False because sparrow is only a producer
(D) False because birds do not eat insects
Ans: A

Q101. Human beings can function at
(A) More than one trophic level in a food chain (e.g. as primary consumer when vegetarian and higher when non-vegetarian)
(B) Only one trophic level always
(C) Only as top carnivore
(D) Only as producer
Ans: A

Q102. There are certain limitations of ecological pyramids such as it does not take into account
(A) The same species belonging to two or more trophic levels
(B) Only energy loss
(C) Only biomass
(D) Only number of organisms
Ans: A

Q103. Ecological pyramids assume a simple food chain, something that
(A) Almost never exists in nature
(B) Always exists in nature
(C) Exists only in aquatic ecosystems
(D) Exists only in terrestrial ecosystems
Ans: A

Q104. Ecological pyramids do not accommodate
(A) A food web
(B) A single food chain
(C) Only producers
(D) Only decomposers
Ans: A

Q105. Saprophytes (decomposers) are
(A) Not given any place in ecological pyramids even though they play a vital role in the ecosystem
(B) Always shown at the base
(C) Always shown at the apex
(D) Shown in all pyramids equally
Ans: A

Q106. Plants are called as producers because they
(A) Fix carbon dioxide
(B) Consume other organisms
(C) Decompose dead matter
(D) Only provide oxygen
Ans: A

Q107. In an ecosystem dominated by trees, the pyramid (of numbers) is
(A) Inverted type
(B) Upright type always
(C) Spindle shaped
(D) Circular
Ans: A

Q108. Common detritivores in our ecosystem are
(A) Earthworms
(B) Only fish
(C) Only birds
(D) Only mammals
Ans: A

Q109. The major reservoir of carbon on earth for the gaseous type of cycle is
(A) Atmosphere or hydrosphere
(B) Only Earth’s crust
(C) Only rocks
(D) Only fossil fuels
Ans: A

Q110. Which one of the following has the largest population in a food chain?
(A) Producers
(B) Primary consumers
(C) Secondary consumers
(D) Decomposers
Ans: A

Q111. The second trophic level in a lake is
(A) Zooplankton
(B) Phytoplankton
(C) Benthos
(D) Fishes
Ans: A

Q112. Secondary producers are
(A) Herbivores
(B) Producers
(C) Carnivores
(D) None of the above
Ans: A

Q113. What is the percentage of photosynthetically active radiation (PAR) in the incident solar radiation?
(A) Less than 50%
(B) 100%
(C) 1-5%
(D) Exactly 50%
Ans: A

Q114. Grazing food chain and detritus food chain differ because
(A) GFC starts with living producers while DFC starts with dead organic matter
(B) Both start with living producers
(C) Both start with dead matter
(D) GFC has no decomposers
Ans: A

Q115. Production and decomposition differ because
(A) Production builds organic matter while decomposition breaks it down to inorganic substances
(B) Both build organic matter
(C) Both break down matter
(D) Production occurs only at night
Ans: A

Q116. Upright and inverted pyramid differ because
(A) Upright has broad base of producers while inverted has narrow base at producer level
(B) Both have broad base always
(C) Both have narrow base always
(D) Inverted has more energy at top
Ans: A

Q117. Food chain and Food web differ because
(A) Food chain is linear while food web is interconnected network of chains
(B) Both are linear
(C) Both are networks
(D) Food web has no producers
Ans: A

Q118. Litter and detritus differ because
(A) Litter is freshly fallen plant material while detritus includes all dead organic matter including fecal matter
(B) Both are same
(C) Litter is only animal waste
(D) Detritus is only living matter
Ans: A

Q119. Primary and secondary productivity differ because
(A) Primary is by producers (plants) while secondary is by consumers
(B) Both are by producers
(C) Both are by consumers
(D) Primary occurs only in water
Ans: A

Q120. The components of an ecosystem include
(A) Abiotic (air, water, soil) and biotic (producers, consumers, decomposers)
(B) Only abiotic components
(C) Only biotic components
(D) Only energy
Ans: A

Q121. Ecological pyramids are defined as
(A) Graphical representation of number, biomass or energy at different trophic levels
(B) Only pictures of ecosystems
(C) Only food chains
(D) Only nutrient cycles
Ans: A

Q122. Pyramid of number in grassland shows
(A) Large number of producers supporting fewer consumers at higher levels
(B) Fewer producers than consumers
(C) Equal numbers at all levels
(D) No producers
Ans: A

Q123. In pyramid of biomass, there is generally
(A) Sharp decrease in biomass at higher trophic levels
(B) Increase in biomass at higher levels
(C) Constant biomass
(D) No relation with trophic levels
Ans: A

Q124. The inverted pyramid of biomass in aquatic ecosystem occurs because
(A) Small standing crop of phytoplankton supports large standing crop of zooplankton
(B) Large phytoplankton supports small zooplankton
(C) No biomass exists in water
(D) Fish have no biomass
Ans: A

Q125. Ideal pyramid of energy shows that primary producers convert only
(A) 1% of the energy in the sunlight available to them into NPP
(B) 10% of sunlight
(C) 50% of sunlight
(D) 100% of sunlight
Ans: A

Q126. Energy flow in an ecosystem is
(A) Unidirectional from sun to producers to consumers to decomposers with loss as heat
(B) Bidirectional and cyclic
(C) Only from consumers to producers
(D) Without any loss
Ans: A

Q127. Nutrient cycling is
(A) The storage and movement of nutrient elements through the various components of the ecosystem; nutrients are repeatedly used
(B) Only one way movement
(C) Only loss of nutrients
(D) Not related to ecosystem
Ans: A

Q128. Nutrient cycling is of two types
(A) Gaseous and sedimentary
(B) Only gaseous
(C) Only sedimentary
(D) Only biological
Ans: A

Q129. Atmosphere or hydrosphere is the reservoir for the
(A) Gaseous type of cycle (e.g., carbon)
(B) Sedimentary type of cycle
(C) Only phosphorus cycle
(D) Only energy flow
Ans: A

Q130. Earth’s crust is the reservoir for
(A) Sedimentary type (e.g., phosphorus)
(B) Gaseous type
(C) Only carbon cycle
(D) Only water cycle
Ans: A

Q131. Products of ecosystem processes are named as ecosystem services, e.g.,
(A) Purification of air and water by forests
(B) Only food production
(C) Only oxygen release
(D) Only decomposition
Ans: A

Q132. In decomposition, complex organic compounds of detritus are converted to carbon dioxide, water and inorganic nutrients by the
(A) Decomposers
(B) Producers
(C) Consumers only
(D) Sunlight directly
Ans: A

Q133. Decomposition involves processes namely
(A) Fragmentation of detritus, leaching and catabolism (as per summary)
(B) Only photosynthesis
(C) Only respiration
(D) Only mineralisation
Ans: A

Q134. The rate of capture of solar energy or total production of organic matter is called as
(A) Gross primary productivity (GPP)
(B) Net primary productivity (NPP)
(C) Secondary productivity
(D) Standing crop
Ans: A

Q135. NPP is the remaining biomass or the energy left after
(A) Utilisation of producers (respiration)
(B) Consumption by herbivores
(C) Decomposition
(D) Leaching
Ans: A

Q136. Secondary productivity is the rate of
(A) Assimilation of food energy by the consumers
(B) Capture of solar energy by plants
(C) Decomposition of detritus
(D) Formation of humus
Ans: A

Q137. In energy flow, plants capture solar energy and then food is transferred from the producers to
(A) Decomposers (via various paths)
(B) Only to herbivores
(C) Only to carnivores
(D) Back to sun
Ans: A

Q138. Organisms of different trophic levels in nature are connected to each other for food or energy relationship forming a
(A) Food chain
(B) Only food web
(C) Only pyramid
(D) Only cycle
Ans: A

Q139. The storage and movement of nutrient elements through the various components of the ecosystem is called
(A) Nutrient cycling
(B) Energy flow
(C) Decomposition only
(D) Productivity
Ans: A

Q140. In an ecosystem dominated by trees, the pyramid of numbers is inverted because
(A) One tree (producer) supports large number of insects and birds at higher levels
(B) Large number of trees support few insects
(C) All levels have equal numbers
(D) No consumers exist on trees
Ans: A

Q141. The pyramid of energy is always upright because
(A) Energy is lost as heat at each trophic level transfer
(B) Energy is gained at each level
(C) Energy remains constant
(D) Energy flows back to producers
Ans: A

Q142. If we count the number of insects feeding on a big tree and then small birds and larger birds, the pyramid of numbers would be
(A) Inverted
(B) Upright
(C) Spindle shaped
(D) Rectangular
Ans: A

Q143. The biomass of fishes far exceeds that of phytoplankton in sea leading to
(A) Inverted pyramid of biomass
(B) Upright pyramid of biomass
(C) No pyramid
(D) Pyramid of numbers only
Ans: A

Q144. Primary productivity in oceans is low compared to land despite large area because
(A) As stated (reason to be discussed with teacher; text gives the numerical difference only)
(B) Oceans have more plants
(C) Oceans have no consumers
(D) Oceans have higher sunlight
Ans: A

Q145. Detritus is the raw material for
(A) Decomposition
(B) Photosynthesis
(C) Primary production
(D) Stratification
Ans: A

Q146. All the steps in decomposition (fragmentation, leaching, catabolism, humification and mineralisation) operate
(A) Simultaneously on the detritus
(B) Only one after another in strict sequence without overlap
(C) Only in aquatic ecosystems
(D) Only at night
Ans: A

Q147. Humification and mineralisation occur during decomposition in the
(A) Soil
(B) Air only
(C) Water surface only
(D) Leaves of living plants
Ans: A

Q148. Being colloidal in nature, humus serves as
(A) A reservoir of nutrients
(B) A source of only heat
(C) A source of only light
(D) An inhibitor of all microbial activity
Ans: A

Q149. Warm and moist environment favour decomposition whereas low temperature and anaerobiosis
(A) Inhibit decomposition resulting in build up of organic materials
(B) Favour fast decomposition
(C) Have no effect
(D) Only affect producers
Ans: A

Q150. The important point to note is that the amount of energy
(A) Decreases at successive trophic levels
(B) Increases at successive trophic levels
(C) Remains constant at all levels
(D) Is created at higher levels
Ans: A

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