1. Pyramid of numbers in a grassland/true ecosystem is
(a) always inverted
(b) always upright
(c) both A and B
(d) spindle-shaped
2. Food chain in which micro-organisms breakdown the food formed by primary producers is
(a) parasitic food chain
(b) detritus food chain
(c) consumer food chain
(d) predator food chain
3. Pick up the correct food chain
(a) Grass Chamelion Insect Bird
(b) Grass Fox Rabbit Bird
(c) Phytoplankton Zooplankton Fish
(d) Fallen leaves Bacteria Insect larvae
4. Pedology is science of
(a) earth
(b) soil
(c) diseases
(d) pollution
5. River water deposits
(a) loamy soil
(b) alluvial soil
(c) laterite soil
(d) sandy soil
6. Study of inter-relationships between organisms and their environment is
(a) ecology
(b) ecosystem
(c) phytogeography
(d) ethology
7. Pyramid of numbers deals with number of
(a) species in an area
(b) individuals in a community
(c) individuals in a tropic-level
(d) subspecies in a community
8. Pyramid of numbers in a pond
ecosystem is
(a) irregular
(b) inverted
(c) upright
(d) spindle shaped
9. The pyramid which cannot be inverted in a stable ecosystem is that of
(a) Biomass
(b) Number
(c) Energy
(d) All the above
10. In grass-deer-tiger food chain, grass biomass is one tonne. The tiger biomass shall be
(a) 100 kg
(b) 10 kg
(c) 200 kg
(d) 1 kg
11. In a biotic community, the most important factor for survival of an animal is
(a) day length
(b) soil moisture
(c) green food
(d) predators
12. Second most important trophic level in a lake is
(a) Zooplankton
(b) Phytoplankton
(c) Benthos
(d) Neuston
13. Bulk CO2 fixation occurs in
(a) Crop plants
(b) Oceans
(c) Tropical rain forests
(d) Temperature forests
14. Desert plants are generally
(a) viviparous
(b) succulent
(c) herbaceous
(d) heterophyllus
15. Which of the following does not have stomata?
(a) hydrophytes
(b) mesophytes
(c) xerophytes
(d) submerged hydrophytes
16. If we completely remove the decomposers from an ecosystem, its functioning will be adversely affected, because
(a) energy flow will be blocked
(b) herbivores will not receive solar energy
(c) mineral movement will be blocked
(d) rate of decomposition will be very high
17. The primary succession refers to the development of communities on a
(a) fleshly cleared crop field
(b) forest clearing after devastating fire
(c) pond, freshly filled with water after a dry phase
(d) newly-exposed habitat with no record of earlier vegetation
18. Which of the following is the most stable ecosystem?
(a) Forest
(b) Desert
(c) Mountain
(d) Ocean
19. In a biotic community, the primary consumers are
(a) carnivores
(b) omnivores
(c) detritivores
(d) herbivores
20. Which of the following pairs is a sedimentary type of biogeochemical cycle?
(a) oxygen and nitrogen
(b) phosphorus and sulphur
(c) phosphorus and nitrogen
(d) phosphorus and carbon dioxide
21. Flamingoes breed in
(a) rann of Kutch
(b) chilka lake
(c) sambhar lake
(d) mansarover Lake
22. In a food chain, the largest population is that of
(a) decomposers
(b) producers
(c) primary consumers
(d) tertiary consumers
23. The transfer of energy from one trophic level to another is governed by the 2nd law of thermodynamics. The average efficiency of energy transfer from herbivores to carnivores is
(a) 5%
(b) 10%
(c) 25%
(d) 50%
24. Niche of a species in an ecosystem refers to its
(a) function at its place of occurrence
(b) place of its occurrence
(c) competitive ability
(d) centre of origin
25. Which of the following ecosystems has highest rate of gross primary production?
(a) Grasslands
(b) Mangroves
(c) Coral reefs
(d) Equatorial rain forest
26. During adverse season, therophytes survive by
(a) bulbs
(b) corms
(c) rhizomes
(d) seeds
27. The rate at which light energy is converted to the chemical energy of organic molecules is the ecosystem‘s
(a) net primary productivity
(b) gross primary productivity
(c) net secondary productivity
(d) gross secondary productivity
28. Warm ocean surge of the Peru Current reoccurring every 5-8 years or so in the East Pacific of South America is widely known as
(a) Gulf Stream
(b) El Nino
(c) Aye Aye
(d) Magnox
29. Upper part of sea/aquatic ecosystem contains
(a) plankton
(b) nekton
(c) plankton and nekton
(d) benthos
30. What is true of ecosystem?
(a) Primary consumers are least dependent upon producers
(b) Primar y consumers out-number producers
(c) Producers are more than primary consumers
(d) Secondary consumers are the largest and most powerful
31. In an ecosystem, which one shows one-way passage
(a) free energy
(b) carbon
(c) nitrogen
(d) potassium
32. Sudden mass killing of fishes is likely in
(a) mesotrophic lake
(b) oligotrophic lake
(c) salt lake
(d) eutrophic lake
33. Pneumatophores are characteristic of plants growing in
(a) saline soils
(b) sandy soils
(c) marshy places and salt lakes
(d) dryland regions
34. The greatest biomass of autotrophs in the oceans is that of
(a) sea grasses and slime moulds
(b) free floating microalgae, cyanobacteria and nanoplankton
(c) benthic brown algae,coastal red algae and daphnids
(d) benthic diatoms and marine viruses
35. Bamboo plant is growing in a fir forest then what will be the trophic level of it?
(a) First trophic level (T1)
(b) Second trophic level (T2)
(c) Third trophic level (T3)
(d) Fourth trophic level (T4)
36. Which of the following is expected to have the highest value (gm/m2 /yr) in a grassland ecosystem?
(a) Secondary Production
(b) Tertiary Production
(c) Gross Production (GP)
(d) Net Production (NP)
37. If by radiation all nitrogenase enzymes are inactivated, then there will be no
(a) fixation of nitrogen in legumes
(b) fixation of atmospheric nitrogen
(c) conversion from nitrate to nitrite in legumes
(d) conversion from ammonium to nitrate in soil
38. An ecosystem which can be easily damaged but can recover after some time if damaging effect stops will be having
(a) low stability and high resilience
(b) high stability and low resilience
(c) low stability and low resilience
(d) high stability and high resilience
39. Barophilic prokaryotes:
(a) grow and multiply in very deep marine sediments
(b) occur in water containing high concentrations of barium hydroxide
(c) readily grow and divide in sea water enriched in any soluble salt of barium
(d) grow slowly in highly alkaline frozen lakes at high altitudes
40. More than 70% of world‘s freshwater is contained in:
(a) polar ice
(b) glaciers and mountains
(c) antarctica
(d) greenland
41. Which one of the following is not used for construction of ecological pyramids?
(a) Number of individuals
(b) Rate of energy flow
(c) Fresh weight
(d) Dry weight
42. Which one of the following ecosystem types has the highest annual net primary productivity?
(a) tropical deciduous forest
(b) temperate evergreen forest
(c) temperate deciduous forest
(d) tropical rain forest.
43. A lake near a village suffered heavy mortality of fishes within a few days. Consider the following reasons for this?
(a) Lots of urea and phosphate fertilizer were used in the crops in the vicinity
(b) The area was sprayed with DDT by an aircraft
(c) The lake water turned green and stinky
(d) Phytoplankton populations in the lake declined initially thereby greatly reducing photosynthesis. Which two of the above were the main causes of fish mortality in the lake?
44. About 70% of total global carbon is found in
(a) grasslands
(b) agroecosystems
(c) oceans
(d) forests
45. The slow rate of decomposition of fallen logs in nature is due to their
(a) low moisture content
(b) poor nitrogen content
(c) anaerobic environment around them
(d) low cellulose content
46. Consider the following statements concerning food chains
(a) removal of 80% tigers from an area resulted in greatly increased growth of vegetation
(b) removal of most of the carnivores resulted in an increased population of deers
(c) the length of food chains is generally limited to 3-4 trophic levels due to energy loss
(d) the length of food chains may vary from 2 to 8 trophic levels Which two of the above statements are correct?
47. The correct sequence of plants in a hydrosere is:
(a) Volvox → Hydrilla → Pistia →Scirpus Lantana → Oak
(b) Pistia →Volvox →Scirpus →Hydrilla → Oak →Lantana
(c) Oak→Lantana →Volvox →Hydrilla → Pistia →Scirpus
(d) Oak →Lantana →Scirpus →Pistia → Hydrilla →Volvox
48. Which one of the following types of organisms occupy more than one trophic level in a pond ecosystem?
(a) Fish
(b) Zooplankton
(c) Frog
(d) Phytoplankton
49. Study the four statements (a–d) given below and select the two correct ones out of them: (i) A lion eating a deer and a sparrow feeding on grain are ecologically similar in being consumers (ii) Predator star fish Pisaster helps in maintaining species diversity of some invertebrates (iii) Predators ultimately lead to the extinction of prey species (iv) Production of chemicals such as nicotine, strychnine by the plants are metabolic disorders The two correct statements are:
(a) (ii) and (iii)
(b) (iii) and (iv)
(c) (i) and (iv)
(d) (i) and (ii)
50. The biomass available for consumption by the herbivores and the decomposers is called:
(a) net primary productivity
(b) secondary productivity
(c) standing crop
(d) gross primary productivity
51. Mass of living matter at a trophic level in an area at any time is called
(a) standing crop
(b) deteritus
(c) humus
(d) standing state
52. Which one of the following statements for pyramid of energy is incorrect, whereas the remaining three .are correct?
(a) Its base is broad
(b) It shows energy content of different trophic level organisms
(c) It is inverted in shape
(d) It is upright in shape
53. Which one of the following animals may occupy more than one trophic levels in the same ecosystem at the same time?
(a) Sparrow
(b) Lion
(c) Goat
(d) Frog
54. Both, hydrarch and xerarch successions lead to:
(a) medium water conditions
(b) xeric conditions
(c) highly dry conditions
(d) excessive wet conditions
55. Pheretima and its close relatives derive nourishment from:
(a) sugarcane roots
(b) decaying fallen leaves and soil organic matter.
(c) soil insects
(d) small pieces of fresh fallen leaves of maize, etc.
56. Which one of the following is not a gaseous biogeochemical cycle in ecosystem?
(a) Sulphur cycle
(b) Phosphorus cycle
(c) Nitrogen cycle
(d) Carbon cycle
57. Identify the possible link ―A‖ in the following food chain: Plant insect – frog ―A‖ Eagle
(a) Rabbit
(b) WoIf
(c) Cobra
(d) Parrot
58. Which one of the following is not a function of an ecosystem
(a) Energy flow
(b) Decomposition
(c) Productivity
(d) Stratification
59. The upright pyramid of number is absent in
(a) Pond
(b) Forest
(c) Lake
(d) Grassland
60. The rate of formation of new organic matter by rabbit in a grassland, is called
(a) net productivity
(b) secondary productivity
(c) net primary productivity
(d) gross primary productivity
61. The second stage of hydrosere is occupied by plants like
(a) Azolla
(b) Typha
(c) Salix
(d) Vallisneria
62. Natural reservoir of phosphorus is:
(a) Animal bones
(b) Rock
(c) Fossils
(d) Sea water
63. Which one of the following processes during decomposition is correctly described?
(a) Humification-Leads to the accumulation of a dark coloured substance humus which undergoes microbial action at every fast rate
(b) Catabolism – Last step decomposition under fully anaerobic condition
(c) Leaching –water soluble inorganic Nutrient rise to the top level of soil
(d) Fragmentation –Carried out by organisms such as earthworm.
64. Secondary productivity is rate of formation of new organic matter by
(a) Parasite
(b) Consumer
(c) Decomposer
(d) Producer
65. Which one of the following is a primary consumer in maize field ecosystem?
(a) Lion
(b) Grasshopper
(c) Wolf
(d) Phytoplankton
66. When man eats fish which feeds on zooplankton which have eaten small plants, the producer in the chain is
(a) Zooplankton
(b) Small plants
(c) Fish
(d) Man
67. Population of which of the following will be highest in the foodchain?
(a) Decomposer
(b) Primary Producer
(c) Photosynthetic organism
(d) Secondary consumers
68. Mr. X is eating curd/yoghurt. For this food intake in a food chain Mr. X should be considered as occupying
(a) first trophic level
(b) fourth trophic level
(c) second trophic level
(d) third trophic level
69. The primary producers of the deepsea hydrothermal vent ecosystem are
(a) bluegreen algae
(b) coral reefs
(c) green algae
(d) chemosynthetic bacteria
70. which of the following is placed in upper most (highest) level of ecological pyramids.
(a) Herbivores
(b) Carnivors
(c) Primary and Secondary Producers.
(d) Primary and Secondary consumer
71. Which one of the following is a characteristic feature of cropland ecosystem?
(a) Absence of soil organisms
(b) Absence of weeds
(c) Ecological succession
(c) Least genetic diversity
72. The enzyme responsible for the reduction of molecular nitrogen to the level of ammonia in the leguminous root nodule is
(a) nitrite reductase
(b) nitrogenase
(c) nitrate reductase
(d) ammoneases
73.ln a biotic community, the primary consumers are
(a) carnivores
(b) omnivores
(c) detritivores
(d) herbivores
74. Whale is
(a) Primary producer
(b) Herbivorous
(c) Carnivorous, secondary consumer
(d) A decomposer
75.In an ecosystem the rate of production of organic matter during photosynthesis is termed as
(a) secondary productivity
(b) net productivity
(c) net primary productivity
(d) gross primary productivity.
76. The functional efficiency of ecosystem is effected when decomposers are removed from it, because..
(a) Energy flow will stop
(b) Rest components decomposetion will become faster
(c) Herbivous will not get sun light
(d) Flow of nutrient will stop
77. During ecological succession
(a) the numbers and types of animals remain constant
(b) the changes lead to a community that is in near equilibrium with the environment and is called pioneer community
(c) the gradual and predictable change in species composition occurs in a given area
(d) the establishment of a new biotic community is very fast in its primary phase
78. Which age group in pyramid indicate less reproductive potential ?
(a) Bell shaped
(b) Triangular
(c) Inverted Bell shaped
(d) All of them have equal( same) potential
79. Vertical distribution of different species occupying different levels in a biotic community is known as
(a) divergence
(b) zonation
(c) pyramid
(d) stratification
80. If earth is considered a unit region then biosphere can be compared to….
(a) Eco-System
(b) Population
(c) Biotic Community
(d) Species
81. Food chain in which microorganisms breakdown the food formed by primary producers is
(a) parasitic food chain
(b) detritus food chain
(c) consumer food chain
(d) predator food chain.
82. Which two distinct microbial processes are responsible for the release of fixed nitrogen as dinitrogen gas (N2) to the atmosphere?
(a) Aerobic nitrate oxidation and nitrite reduction
(b) Decomposition of organic nitrogen and conversion of dinitrogen to ammonium compounds
(c) Enteric fermentation in cattle and nitrogen fixation by Rhizobium in root nodules of legumes
(d) Anaerobic ammonium oxidation and Denitrification
83. Which is the reason for highest biomass in aquatic ecosystem?
(a) Nano plankton, blue green algae and green algae
(b) Sea grass and slime moulds
(c) Benthoic and brown algae
(d) Diatoms
84. Which one of the following is not a functional unit of an ecosystem?
(a) Energy flow
(b) Decomposition
(c) Productivity
(d) Stratification
85. Which one of the following is not used for construction of ecological pyramids?
(a) Fresh weight
(b) Dry weight
(c) Number of individuals
(d) Rate of energy flow
86. Mass of living matter at a trophic level in an area at any time is called
(a) humus
(b) standing state
(c) standing crop
(d) detritus
87. Which ecosystem has the maximum biomass ?
(a) Grassland ecosystem
(b) Pond ecosystem
(c) Lake ecosystem
(d) Forest ecosystem
88. What type of ecological pyramid would be obtained with the following data?
Secondary consumer : 120 g
Primary consumer : 60 g
Primary producer : 10 g
(a) Inverted pyramid of biomass
(b) Pyramid of energy
(c) Upright pyramid of biomass
(d) Upright pyramid of numbers
89. Which of the following ecological pyramids is generally inverted?
(a) Pyramid of numbers in grassland
(b) Pyramid of energy
(c) Pyramid of biomass in a forest
(d) Pyramid of biomass in a sea
90. In relation to Gross primary productivity and Net primary productivity of an ecosystem, which one of the following statements is correct?
(a) Gross primary productivity and Net primary productivity are one and same
(b) There is no relationship between Gross primary productivity and Net primary productivity
(c) Gross primary productivity is always less than net primary productivity
(d) Gross primary productivity is always more than net primary productivity
91. Match the trophic levels with their correct species examples in grassland ecosystem.
(a) Fourth trophic level (i) Crow
(b) Second trophic level (ii) Vulture
(c) First trophic level (iii) Rabbit
(d) Third trophic level (iv) Grass
Select the correct option
(a) (b) (c) (d)
(1) (iv) (iii) (ii) (i)
(2) (i) (ii) (iii) (iv)
(3) (ii) (iii) (iv) (i)
(4) (iii) (ii) (i) (iv)
92. In the equation GPP – R = NPP R represents :
(a) Respiration losses
(b) Radiant energy
(c) Retardation factor
(d) Environmental factor
93. The amount of nutrients, such as carbon, nitrogen, phosphorus and calcium present in the soil at any given time, is referred as :
(a) Standing crop
(b) Climax
(c) Climax community
(d) Standing state
Solutions :
1.Solution: (b)
Pyramid of numbers in a grassland ecosystem is always upright. For most ecosystem, like grass and ecosystem. Pyramids of numbers are upright because numbering of organisms decrease at successively higher trophic levels. Trophic level refers to the organisms, position in the food chain.
2.Solution: (b)
Detritus food chain being with dead organic matter with dead plant parts, animals and their excretory product which is being acted upon by decomposers such as saprophytes to obtain energy needed for their survival.
3.Solution: (c)
Phytoplankton → zooplankton → Fish. This is a type of food chain in aquatic ecosystem.
4.Solution: (b)
Soil is the uppermost weathered layer or earth’s crust and is composed of minerals and partly decomposed organic matter. Pedologist is a scientist who studies origin, composition and distribution of soil and the materials from which the soil is made.
5.Solution: (b)
River water deposits alluvial soil. Alluvial soil- formed by the alluvium deposition by the rivers when they slowly lose their carrying capacity due to decrease in velocity. These consist of diverse ratio of sand, silt and clay. These the most widespread soil in India the entire northern plains as loamy soil. It contains roughly equal amount of sand silt and clay. It is more fertile than sandy soil. Laterite soilformed and hot wet tropical areas are formed by intensive and long lasting weathering of underlying rocks and are rich in iron and aluminium.
6.Solution: (a)
German biologist Ernst Haeckel coined the term ‘ecology’, the study of interrelationship between organisms and their environment. Ecosystem, consist of different communities of organism and the physical environment with which they interact. Phytogeography is the study of geographic distribution of plants species on earth.
7.Solution: (c)
Pyramid of number represents the number of individuals on each tropic level.
8.Solution: (c)
Pyramid of numbers of pond ecosystem is upright.
9. Solution: (c)
Energy pyramid can not be inverted because energy always flows in one direction only. According to 10% law of energy transfer given by Lindemann (1972), during transfer of energy from one trophic level to other there is always loss in respiration and other activities only 10% of
energy is transfered to neat trophic level. So the amount of energy flow decreases with successive trophic levels.
10.Solution: (b)
Only 10% of the mass is flown from one tropic level to another in the form of energy.
11.Solution: (c)
Food is necessary for life.
12.Solution: (a)
First tropic level in a lake is phytoplankton, second is zooplankton.
13.Solution: (b)
Due to majority of phytoplanktons.
14.Solution: (b)
Succulent plants are fleshy xerophytes, which can grow in low water level area (desert). That is why, they are called as desert plants.
15.Solution: (d)
In submerged hydrophytes whole plant body remains under water. e.g. Ceratophyllum and Utricularia. In these plants, stomata is absent and gaseous exchange takes place through general body surface.
16.Solution: (c)
The decomposers act on the dead organic matter and break them down into simpler compounds and minerals.
17.Solution: (d)
The primary succession means the development of communities only on a newly exposed habitat with no record of earlier vegetation.
18.Solution: (d)
The oceans cover about 2/3 of the whole surface of our earth. Thus it is the most stable ecosystem, because of buffering action by water.
19.Solution: (d)
In a biotic community the herbivores (goat, deer) are those animals, which consume the primary producers (green plants). Hence they are primary consumers.
20.Solution: (b)
Biogeochemical cycles: Two types: (a) Gaseous: Biogenetic materials involved in circulation are gases eg. N2, O2, CO2 etc. (b) Sedimentary: Biogenetic materials involved in circulation are non-gaseous eg. P2, Ca, Setc. forms rocks.
21.Solution: (b)
Flamingoes breed in chilka lake.
22.Solution: (b)
Producers are the direct and indirect source of food for all the trophic levels. They are always more in number.
23.Solution: (b)
According to the 10% law, at each trophic level, only 10% of the energy received is transfered to the next trophic level.
24.Solution: (a)
Niche is a specific part of the habitat that is determined by the functioning of the population like shelter, type of food, season etc.
25.Solution: (d)
Coral reefs are often called “rainforest of the sea”. It forms some of the most diverse ecosystem on earth. Coral reef ecosystem have the highest grass primary productivity in the sea.
26.Solution: (d)
Therophytes are those plants which survive the adverse season like winter as a seed and complete their life cycle between spring and autumn.
27. Solution: (b)
The rate at which organic molecules are formed in a green plant is called gross productivity.
28.Solution: (b)
El. Nino flows to the north from Antarctica along the west coast of South America to S. Ecuador, the west. It reoccurs after every 5
to 8 yrs. El Nino and La Nina are officially defined as sustained sea surface temperature anomalies of magnitude greater than 0.5°C across the central tropical Pacific Ocean. When the condition is met for a period of less than five months, it is classified as El Nino or La Nina conditions; if the anomaly persists for five months or longer, it is classified as an El Nino or La Nina episode.
29.Solution: (a)
Plankton → Organisms passively floating in upper water. Nekton → Actively swimming Benthos → Lead sedentary life upon the sea bottom
30.Solution: (c)
In an ecosystem producers (green plants) are always more than consumers (herbivores, carnivores etc.)
31. Solution: (a)
Energy flow takes place only in one direction i.e., producers → herbivores → carnivores whereas, nutrients use carbon, nitrogen and potassium shows cyclic flow.
32.Solution: (d)
Organic pollutants provide nutrients for stimulating growth of algae and other plants. Algal bloom reduces availability of light to submerged plants which get killed. The dead submerged plants consume more oxygen in decomposition. This reduces availability of oxygen to other life forms
leading to death of organisms. This is known as eutrophication.
33.Solution: (c)
Some plants growing in salty marshes develop special roots for respiration, called pneumatophores. They are (–) vely geotropic.
34.(d) benthic diatoms and marine viruses Solution: (b)
The greatest biomass of autotrophs in the oceans is that of free floating microalgae, cyanobacteria and nanoplankton.
35.Solution: (a)
First trophic level is occupied by producers. Second trophic level is occupied by primary consumers. Third trophic level is occupied by the secondary consumers.
36.Solution: (c)
Grasslands will have highest value of gross production. Net production is obtained after subtracting the respiratory utilization from gross production. Secondary and tertiary production is related with secondary and tertiary consumers respectively.
37.Solution: (a)
Nitrogenase is an enzyme involved in biological nitrogen fixation. Enzyme nitrate reductase is involved in conversion of nitrate to nitrite. Conversion of ammonia to nitrate is carried out by Nitrosomonas and Nitrobacter.
38.Solution: (a)
An ecosystem having low stability can be easily damaged. An ecosystem having high resilience will take less time to recover.
39.Solution: (a)
Barophiles are bacteria which live in high pressure environments. They are generally found on ocean floors, where pressure generally exceeds 380 atm (38 MPa). Some have been found at the bottom of the Pacific Ocean where the maximum pressure is roughly 117 MPa.
40.Solution: (a)
Three fourth surface of earth is covered by oceans which contain 97.5% of total water. It is marine water with about 3.5% salt content only 2.5% is fresh water which occurs on land. Most of this water (1.97%) occurs as frozen ice caps and glaciers, 0.5% fresh water occurs as ground water.
Rivers and lakes contain 0.02%, soil 0.01% while atmosphere possesses 0.001% of water as vapours.
41.Solution: (c)
Fresh weight is not used for the construction of ecological pyramids because the total fresh weight does not change into energy. Hence we can say that fresh weight is not continuous in the tropic levels.
42.Solution: (d)
They are found in the equatorial regions rainfall exceeds 140 cm. The warm humid climate supports broad leaved evergreen plants. Productivity is very high (12000 k. cal/m2/ year). The vegetation show stratification into two or more well defined layers.
43. Solution: (c)
Lots of urea and phosphate fertilizer were used in the crops in the vicinity and the lake water turned green and stinky. Due to this, lake near a village suffered heavy mortality of fishes within a few days.
44.Solution: (c)
About 70% oftotal global carbon is found in oceans. This oceanic reservoir regulates the amount of carbon dioxide in the atmosphere. Atmosphere contains only about one percent of total global carbon.
45.Solution: (d)
The slow rate of decomposition of fallen logs in nature is due to their low cellulose content. It plays an essential part in abscission in plants, while microbial cellulases enable the digestion of plant material by herbivores.
46.Solution: (a)
Food chain is the transfer of energy from green plants (Primary producers), through a sequence of organisms occupies in a food chain is known as its trophic level. Therefore, statements b and c are correct.
47.Solution: (a)
The correct sequence of plants in a hydrosere is Volvox, Hydrilla, Pistia, Scirpus, Lanatana and Oak. A hydrosere is a plant succession which occurs in a fresh water lake. In time, an area of open fresh water such as a lake will naturally dry out, ultimately becoming woodland. During this
change, a range of different landtypes such as swamp and marsh will succeed each other. The succession from open water to climax woodland is likely to take at least two hundred years.
48. Solution: (a)
A pond ecosystem is a delicate balance of fish, plants and other animals. Fish occupy more than one tropic level in pond ecosystem. Small fishes act as secondary consumer. They feed on primary consumer. Large fishes act as tertiary consumer. They feed on smaller fish.
49.Solution: (d)
The statement (i) and (ii) are correct. The statement (iii) is incorrect because predators cannot lead to the extinction of prey species. Predator and prey evolve together. The statement (iv) is incorrect because chemical such as nicotine and strychnine produced by the plants are not metabolic disorders but are metabolic wastes.
50.Solution: (a)
The biomass available for consumption by the herbivores and the decomposers is called net primary productivity. It is equal to the rate of organic matter created by photosynthesis minus the rate of respiration and other losses.
51.Solution: (a)
A standing crop is the quantity or total weight or energy content of the organism, which are in a particular location at a particular time.
52.Solution: (c)
An energy pyramid is the graphical representation of the tropic level (nutritionals) by which the incoming solar energy is transferred into an cosystem. It can never be inverted in shape.
53.Solution: (a)
It feeds upon grains hence called primary consumer and can also feed on insects hence called secondary consumer at the same time in the same ecosystem.
54. Solution: (a)
Hydrarch succession takes place in wetter areas and xerarch succession respectively, which takes place in dry areas. So, both hydrarch and xerarch successions leads to medium water conditions.
55.Solution: (b)
Earthworm derives its nutrition from decaying fallen leaves and soil organic matter. Thus the type of feeding in earthworm is detritus.
56.Solution: (b)
Phosphorus is mostly used as phosphate. Its reservoir pool is phosphate rocks while cycling pool is soil for terrestrial ecosystems and water for aquatic ecosystems.
57.Solution: (c)
58.Solution: (d)
Four important functional aspects of the ecocystem are (i) Productivity (ii) Decomposition, (iii) Energy flow and (iv) Nutrient cycling.
59.Solution: (b)
60.Solution: (b)
At the trophic level of consumers the rate at which food energy is assimilated is called secondary productivity. Rabbit is a consumer.
61.Solution: (d)
A hydrosere is a plant succession which occurs in a freshwater lake. Second stage of hydrosere is submerged stage that is represented by Vallisneria, Hydrilla, Elodea, Utricularia etc.
62.Solution: (b)
The natural reservoir of phosphate is rock which contains phosphorus in the form of phosphates when rocks are weathered, minute amounts of these phosphate dissolve in soil solution and are absorbed by the roots of the plants. Herbivores and other animals obtain this element from
plants.
63(d) Humification , catabolism , leaching and fragmentation are the steps of decomposition which operate simultaneously on the detritus.
Fragmentation is breaking down detritus into smaller particles by detritivores like earthworm. By the process of leaching, water soluble inorganic nutrients go down into soil horizon and get precipitated as unavailable salts. Humification occurs at a very slow rate.
64.Solution: (b)
The rate of resynthesis of organic matter by the consumers is known as secondary productivity. It depends upon the loss while transferring energy containing organic matter from the previous trophic level plus the consumption due to respiration and predation. Respiration loss is about 20% for autotrophs, 30% for herbivores and upto 60% in case of carnivores. Therefore net productivity decreases with each trophic level.
65.Solution: (b)
Primary consumers are herbivorous organisms that feed on producers. Carnivores are termed secondary, tertiary etc. consumers depending upon their position in food chain. In food chain on land, grasshopper is a herbivore (primary consumer) while wolf and lion are carnivores. Phytoplanktons are producers in aquatic food chains
66.Solution: (b)
Plants are producers which can prepare their food by the process of photosynthesis. Zooplanktons, fish and man are primary, secondary and tertiary carnivores respectively
67.(a) Decomposers form the largest population in the food chain. These are the organisms that feed on the dead and decaying matter and break down the complex compounds into simpler ones. These include bacteria, fungi, and several other microorganisms. The decomposers form an important part of the food chain.
68.(d) Mr. X eating curd / yoghurt should be considered as occupying third trophic level. Producers or green plants (first trophic level) are consumed by herbivore (second trophic level. And from them curd, yoghurt (made from dairy breed) is consumed by third trophic level like man.
69.(d) chemosynthetic bacteria
70.(b) A carnivore, meaning “meat eater”, is an animal whose food and energy requirements derive solely from animal tissue or meat, whether through hunting or scavenging.
71.(a) The cropland ecosystem has the same type of crops and has the least diversity.
72.(b) nitrogenase
73.(d) In a biotic community, the primary consumers or first-order consumers are herbivores, they feed on producers. They are also called key industry animals because they convert plant material into animal material
74.(c) Secondary consumers are mainly carnivores who prey on other animals. Omnivores, who feed on both plants and animals, can also be considered a secondary consumer. Examples of secondary consumers: Carnivorous fish, seals, sea stars, whales, squid, some crabs ,lobsters etc.
75.(d) The amount of energy accumulation in green plants as biomass or organic matter per unit area over a time period is known as primary productivity. The rate of total capture of energy, or the rate of total production of organic material (biomass), is known as gross primary productivity
76.(d) Flow of nutrient will stop
77.(c) Biotic or ecological succession is the natural development of a series of biotic communities at the same site, one after the other till a climax community develops which does not change further because it is in perfect harmony with the environment of the area. The change is orderly and sequential. There is a parallel change in the physical environment. During an ecological succession, the numbers and types of animals go on increasing with time. The community that is in near equilibrium with the environment is called climax community. The establishment of a new biotic community is slow in its primary phase but gradually becomes fast in its secondary phase.
78. (c) Inverted Bell shaped
79.(d) stratification
80.(b) Biotic Community
81.(b) The dead organic matter of plants or animals is called as detritus. While a part of it remains on the soil surface as litter, the other part enters the soil. Many animals such as protozoans, nematodes, insects etc., depend on detritus and hence they are called as detritivores. Even the human beings are detritivores when they eat cooked food. From detritus, the chain proceeds to detritivores, then to carnivores and finally to top carnivores.
82.(d) Denitrification is a chemical process in which nitrates in the soil are reduced to molecular nitrogen (N.) which is released into the atmosphere. It is done by denitrifying bacteria like Pseudomonas denitrificans. Anaerobic oxidation of ammonium (NH4) also releases nitrogen in the atmosphere.
83.(c) The benthic region includes all the sea floor from the wavewashed shoreline to the greatest depths. Depending upon the penetration of light it is subdivided into two main zones : the lighted or littoral zone and the deep sea system. Due to abundance of light, water, oxygen, carbon dioxide and less salinity of water, the tidal zone is characterized by exhorbitant growth of plants. The dense growth of vegetation, on the other hand, provides shelter and food for animals. A wide variety of algae, few grasses and animals of every phylum of animal kingdom are represented in this region.
84.(d) functional unit of an ecosystem
85.(a) Ecological pyramids represents the trophic structure and trophic function of an ecosystem. In an ecological pyramid, the first trophic level forms the base and successive trophic levels the tiers which make up the apex. Ecological pyramids may be of three general types pyramid of number, pyramid of biomass and pyramid of energy. Pyramid of biomass i.e. the living weight of the organisms of the food chain present at any time in an ecosystem forms the pyramids of biomass. The pyramid of biomass indicates the decrease or the gradual reduction in biomass at each trophic levels from base to apex. Fresh weight is not used in ecological pyramids
86.(c) A standing crop is the total dried biomass of the living organisms present in a given environment. This includes both natural ecosystems and agriculture
87. (d)Forest ecology is the scientific study of the interrelated patterns, processes, flora, fauna and 4ecosystems in forests. The management of forests is known as forestry, silviculture, and forest management. In forest ecosystems productivity is also high that contributes to maximum biomass.
88 (a)the inverted pyramid of biomass, usually found in aquatic ecosystem.
• Pyramid of energy is always upright
• Upright pyramid of biomass and numbers are not possible, as the data depicts
primary producer is less than primary consumer and this is less than secondary consumers.
89(d) ecological pyramid is a diagram that shows the relative amounts of energy or matter or numbers of organisms within each trophic level in a food chain or food. The pyramid of biomass in sea is inverted because biomass of fish exceeds that of phytoplankton and in this scenario the biomass of trophic level depends on the reproductive potential and the longevity of the member. Marine environment have inverted biomass pyramids.
90(d) GPP is always more than NPP
91(c)
• Fourth trophic level — Vulture
• Second trophic level — Rabbit
• First trophic level—Grass
• Third trophic level — Crow
92(a) Respiration losses
93 (a) Standing crop
