Class 12/Question Bank
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Created by Titas Mallick
Biology Teacher • M.Sc. Botany • B.Ed. • CTET (CBSE) • CISCE Examiner
Questions on Ecosystem
Choose the correct answer from the given options.
An ecosystem is defined as: a) A group of organisms living together b) A functional unit where living organisms interact with each other and the physical environment c) Only the physical environment d) A collection of plants and animals
Which of the following is NOT a natural ecosystem? a) Forest b) Pond c) Aquarium d) Desert
Abiotic components include: a) Only temperature and light b) Plants and animals c) Temperature, light, water, soil, and minerals d) Only soil and water
Primary producers are also called: a) Heterotrophs b) Autotrophs c) Carnivores d) Decomposers
Which organism is a primary consumer? a) Lion b) Deer c) Eagle d) Bacteria
Decomposers are also known as: a) Autotrophs b) Producers c) Saprotrophs d) Carnivores
In a pond ecosystem, phytoplankton are: a) Primary consumers b) Secondary consumers c) Producers d) Decomposers
Gross Primary Productivity (GPP) is: a) NPP + Respiration b) NPP - Respiration c) Only the energy stored d) Secondary productivity
The formula for Net Primary Productivity is: a) NPP = GPP + R b) NPP = GPP - R c) NPP = GPP × R d) NPP = R - GPP
The first step of decomposition is: a) Leaching b) Fragmentation c) Catabolism d) Humification
Humus is formed during which step of decomposition? a) Fragmentation b) Leaching c) Humification d) Mineralization
Which factor slows down decomposition? a) High temperature b) High lignin content c) Adequate moisture d) Neutral pH
A grazing food chain starts with: a) Dead organic matter b) Producers c) Primary consumers d) Decomposers
In aquatic ecosystems, the major energy flow is through: a) Detritus food chain b) Grazing food chain c) Both equally d) Neither
Trophic level 1 consists of: a) Herbivores b) Carnivores c) Producers d) Decomposers
The pyramid of energy is always: a) Upright b) Inverted c) Spindle-shaped d) Variable
An inverted pyramid of biomass is found in: a) Grassland b) Forest c) Aquatic ecosystems d) Desert
According to the 10% law, energy transfer efficiency is: a) 100% b) 50% c) 10% d) 5%
PAR stands for: a) Photosynthetically Active Radiation b) Primary Active Radiation c) Plant Active Radiation d) Photosynthetic Available Radiation
The wavelength range of PAR is: a) 200-400 nm b) 400-700 nm c) 700-1000 nm d) 100-300 nm
Standing crop refers to: a) Agricultural crops b) Living biomass at a trophic level at a given time c) Dead organic matter d) Soil nutrients
Which of the following is an edaphic factor? a) Temperature b) Rainfall c) Soil pH d) Wind
Chemosynthetic bacteria are found in: a) Ponds b) Forests c) Deep-sea hydrothermal vents d) Grasslands
Secondary consumers are also called: a) Herbivores b) Primary carnivores c) Producers d) Decomposers
Daphnia in a pond ecosystem is a: a) Producer b) Primary consumer c) Secondary consumer d) Decomposer
The process of leaching involves: a) Breaking down of organic matter b) Water-soluble nutrients seeping into soil c) Formation of humus d) Release of CO2
Organic substances that link biotic and abiotic components are: a) Proteins only b) Carbohydrates only c) Humic substances d) Lipids only
In terrestrial ecosystems, major energy flow is through: a) Grazing food chain b) Detritus food chain c) Both equally d) Neither
Quaternary consumers are at trophic level: a) 2 b) 3 c) 4 d) 5
The units for primary productivity are: a) g/m²/day b) g/m²/year c) kg/m²/year d) mg/m²/year
Which organism is NOT a marginal plant in pond ecosystem? a) Typha b) Sagittaria c) Hydrilla d) All are marginal plants
The 10% law was proposed by: a) Charles Darwin b) Raymond Lindeman c) Odum d) Tansley
Food webs are more realistic than food chains because: a) They show linear relationships b) They show complex feeding relationships c) They are simpler d) They have fewer organisms
Anaerobic conditions during decomposition result in: a) Faster decomposition b) Slower decomposition c) No effect d) Complete stoppage
The pyramid of numbers in a forest ecosystem is: a) Upright b) Inverted c) Spindle-shaped d) Rectangular
Hydrilla is an example of: a) Floating plant b) Submerged plant c) Marginal plant d) Emergent plant
Catabolism in decomposition involves: a) Physical breakdown b) Chemical breakdown by enzymes c) Leaching of nutrients d) Humus formation
The least efficient energy transfer occurs at: a) Producer level b) Primary consumer level c) Secondary consumer level d) All levels equally
Inorganic substances in ecosystems include: a) Only carbon dioxide b) Only water c) CO2, O2, N2, water, phosphorus, calcium d) Only nitrogen
Climatic factors include all EXCEPT: a) Temperature b) Rainfall c) Soil pH d) Humidity
The term ecosystem was coined by: a) Odum b) Tansley c) Lindeman d) Clements
Artificial ecosystems are characterized by: a) No human intervention b) Human creation and maintenance c) Only natural processes d) No energy input
Saprophytes are organisms that: a) Produce their own food b) Feed on living organisms c) Feed on dead organic matter d) Are parasitic
The efficiency of photosynthesis in capturing solar energy is: a) 50-60% b) 25-30% c) 10-15% d) 2-10%
Which trophic level has the maximum energy? a) Primary consumers b) Secondary consumers c) Producers d) Tertiary consumers
Mineralization results in the release of: a) Organic compounds b) Inorganic nutrients c) Humus d) Proteins
The pyramid of biomass in grassland is: a) Upright b) Inverted c) Spindle-shaped d) Irregular
Cyclops in a pond is a: a) Producer b) Primary consumer c) Secondary consumer d) Decomposer
Detritivores are organisms that: a) Produce energy b) Break down detritus into smaller particles c) Are primary consumers d) Are producers
The standing state refers to: a) Living biomass b) Inorganic nutrients in soil/water c) Dead organic matter d) Energy content
Lemna is an example of: a) Submerged plant b) Floating plant c) Marginal plant d) Terrestrial plant
The rate of secondary productivity depends on: a) Solar radiation b) Availability of food c) Temperature only d) Soil nutrients
Which step of decomposition is slowest? a) Fragmentation b) Leaching c) Humification d) Mineralization
Estuaries are examples of: a) Terrestrial ecosystems b) Aquatic ecosystems c) Artificial ecosystems d) Desert ecosystems
The energy flow in ecosystems is: a) Bidirectional b) Unidirectional c) Cyclic d) Random
Primary productivity is highest in: a) Deserts b) Tropical forests c) Tundra d) Grasslands
The organisms at the highest trophic level are usually: a) Most numerous b) Least numerous c) Producers d) Decomposers
Nutrients in ecosystems show: a) Unidirectional flow b) Cyclic movement c) Linear movement d) Random distribution
The base of any ecological pyramid represents: a) Primary consumers b) Producers c) Secondary consumers d) Decomposers
Vallisneria is a: a) Floating plant b) Submerged plant c) Marginal plant d) Terrestrial plant
The most stable component of soil organic matter is: a) Proteins b) Carbohydrates c) Humus d) Lipids
Food chains are limited to 4-5 trophic levels because: a) Insufficient space b) Energy loss at each level c) Lack of organisms d) Competition
Azolla is a: a) Submerged plant b) Floating plant c) Marginal plant d) Decomposer
The term 'standing crop' was introduced by: a) Odum b) Tansley c) Lindeman d) Clements
Decomposition is fastest in: a) Cold, dry conditions b) Hot, humid conditions c) Waterlogged conditions d) Acidic conditions
Pistia is an example of: a) Submerged plant b) Floating plant c) Marginal plant d) Terrestrial plant
The pyramid of numbers in parasitic food chains is: a) Upright b) Inverted c) Spindle-shaped d) Rectangular
Kingfisher in a pond ecosystem is a: a) Primary consumer b) Secondary consumer c) Tertiary consumer d) Producer
The process of photosynthesis converts: a) Organic to inorganic b) Inorganic to organic c) Light to chemical energy d) Both b and c
Detritus food chains are more important in: a) Aquatic ecosystems b) Terrestrial ecosystems c) Both equally d) Neither
The efficiency of energy transfer from one trophic level to the next is called: a) Ecological efficiency b) Primary productivity c) Secondary productivity d) Gross productivity
Aspergillus in pond ecosystem is a: a) Producer b) Primary consumer c) Secondary consumer d) Decomposer
The total amount of solar energy trapped by producers is: a) NPP b) GPP c) Secondary productivity d) Biomass
Lignin-rich detritus decomposes: a) Rapidly b) Slowly c) At normal rate d) Not at all
Tundra is an example of: a) Aquatic ecosystem b) Terrestrial ecosystem c) Artificial ecosystem d) Marine ecosystem
The energy source for chemosynthetic bacteria is: a) Sunlight b) Chemical compounds c) Organic matter d) Heat
Penicillium in aquatic ecosystems acts as a: a) Producer b) Primary consumer c) Secondary consumer d) Decomposer
The pyramid of energy follows: a) Law of conservation of energy b) Law of thermodynamics c) Both a and b d) Neither
Volvox is an example of: a) Zooplankton b) Phytoplankton c) Fish d) Decomposer
The process that makes nutrients available to producers is: a) Photosynthesis b) Respiration c) Decomposition d) Transpiration
Spirogyra is a: a) Primary consumer b) Secondary consumer c) Producer d) Decomposer
The amount of energy available to consumers is: a) GPP b) NPP c) Total solar energy d) PAR
Diatoms are examples of: a) Zooplankton b) Phytoplankton c) Fish d) Bacteria
The nutrient pool in ecosystems is also called: a) Standing crop b) Standing state c) Biomass d) Productivity
Temperature affects decomposition by: a) Affecting enzyme activity b) Affecting microbial growth c) Both a and b d) Neither
Earthworms in decomposition act as: a) Decomposers b) Detritivores c) Producers d) Consumers
The concept of trophic levels was introduced by: a) Lindeman b) Odum c) Tansley d) Elton
Grazing food chains are dominant in: a) Forests b) Grasslands c) Aquatic systems d) Deserts
Cyanobacteria are: a) Producers b) Primary consumers c) Secondary consumers d) Decomposers
The term PAR was coined by: a) Odum b) Lindeman c) McCree d) Tansley
Moisture affects decomposition by: a) Affecting microbial activity b) Affecting enzyme function c) Both a and b d) Neither
The inverted pyramid of biomass occurs because: a) Producers are small and reproduce rapidly b) Consumers are large c) Energy is lost d) Nutrients are limited
Crop fields are examples of: a) Natural ecosystems b) Artificial ecosystems c) Aquatic ecosystems d) Forest ecosystems
The 10% law applies to: a) Energy transfer only b) Biomass transfer only c) Both energy and biomass d) Neither
Chitin-rich detritus decomposes: a) Rapidly b) Slowly c) At normal rate d) Instantaneously
Aquariums are examples of: a) Natural ecosystems b) Artificial ecosystems c) Terrestrial ecosystems d) Marine ecosystems
The process of humification produces: a) Inorganic nutrients b) Simple organic compounds c) Humus d) CO2
Primary consumers in aquatic ecosystems are mainly: a) Fish b) Zooplankton c) Bacteria d) Algae
The ecological efficiency is highest between: a) Producers and primary consumers b) Primary and secondary consumers c) Secondary and tertiary consumers d) All levels are equal
Standing state includes: a) Living organisms only b) Dead organic matter only c) Inorganic nutrients only d) All of the above
Answer in one word or one sentence.
Answer in 2-3 sentences.
Answer in 4-5 sentences with detailed explanations.
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