Ecosystem
Each subtopic includes About section, revision page link, 10 preview questions, and practice CTAs.
Ecosystem Structure and Function
SubtopicEcosystem Structure and Function under Ecosystem for Grade 12 CBSE.
Preview questions (no answers)
- 1.
An ecosystem consists of:
A.Only biotic components
B.Only abiotic components
C.Both biotic and abiotic components
D.Only producers
- 2.
The rate of formation of new organic matter by consumers is called:
A.Net primary productivity
B.Gross primary productivity
C.Secondary productivity
D.Net community productivity
- 3.
Standing state refers to the amount of ________ in the soil at a given time.
A.Biomass
B.Inorganic nutrients
C.Living organisms
D.Energy
- 4.
Which of the following is a primary consumer in an aquatic ecosystem?
A.Phytoplankton
B.Zooplankton
C.Whale
D.Large fish
- 5.
Which of the following ecosystems would likely have the highest Net Primary Productivity per unit area?
A.Desert
B.Tropical Rainforest
C.Deep Ocean
D.Arctic Tundra
- 6.
Which of the following is NOT a functional unit of an ecosystem?
A.Productivity
B.Stratification
C.Decomposition
D.Energy flow
- 7.
Net Primary Productivity () is the available biomass for consumption by:
A.Decomposers only
B.Herbivores and decomposers
C.Producers themselves
D.Carnivores only
- 8.
Succession that occurs in areas where natural biotic communities have been destroyed, such as in abandoned farm lands or burned forests, is known as:
A.Primary succession
B.Secondary succession
C.Autogenic succession
D.Allogenic succession
- 9.
Primary production is defined as the amount of biomass produced per unit area over a time period by plants during photosynthesis. It is expressed in units of:
A.B.C.D. - 10.
Atmospheric input of phosphorus through rainfall is:
A.Equal to the atmospheric input of carbon
B.Much larger than the atmospheric input of carbon
C.Much smaller than the atmospheric input of carbon
D.The primary source of phosphorus for land plants
Download the worksheet for Ecosystem - Ecosystem Structure and Function to practice offline. It includes additional chapter-level practice questions.
Productivity and Decomposition
SubtopicProductivity and Decomposition under Ecosystem for Grade 12 CBSE.
Preview questions (no answers)
- 1.
Humus is colloidal in nature and because of this, it:
A.Speeds up catabolism
B.Acts as a reservoir of nutrients
C.Makes the soil acidic
D.Is easily washed away by rain
- 2.
Which of the following is NOT a step in the process of decomposition?
A.Fragmentation
B.Humification
C.Photosynthesis
D.Catabolism
- 3.
In the context of the carbon cycle and ecosystem functioning, decomposition acts as a:
A.Nutrient sink
B.Release mechanism for nutrients
C.Barrier to nutrient flow
D.Producer of energy
- 4.
Why is the NPP of the biosphere only 170 billion tons when the ocean covers more than 2/3rds of the Earth?
A.Oceans have no plants
B.Oceans are limited by nutrients and light
C.Oceans have too much oxygen
D.Oceans have no decomposers
- 5.
In the energy flow of a terrestrial ecosystem, the Net Primary Productivity () can follow different pathways. Based on the provided flowchart, which pathway represents the transition of organic matter from the producers into the Detritus Food Chain (DFC)?
A.Pathway A (Herbivory)
B.Pathway B (Litterfall and Death)
C.Process of Decomposition
D.Process of Mineralization
- 6.
The following diagram represents the energy budget of a primary consumer (herbivore) in a grassland ecosystem. Which labeled component specifically represents the 'Secondary Productivity'?
A.Assimilated Energy
B.Respiration Loss
C.Biomass for Growth and Reproduction
D.Egested Waste
- 7.
What happens to the inorganic nutrients during the step of 'Mineralization'?
A.They are converted into organic compounds by microbes
B.They are released from the humus into the soil for plant uptake
C.They are lost forever to the deep layers of the Earth
D.They are used by detritivores to build their cell walls
- 8.
What happens to the mineralization rate if the soil temperature drops from to in a temperate forest?
A.It remains constant.
B.It increases because cold-adapted bacteria take over.
C.It decreases significantly, leading to an accumulation of the humus layer.
D.It stops permanently and cannot be restarted.
- 9.
Which of these substances is the main 'input' for the process of decomposition?
A.Solar radiation
B.Detritus
C.Inorganic minerals
D.Oxygen and Glucose
- 10.
Which of the following describes the relationship between the 'Grazing Food Chain' (GFC) and the 'Detritus Food Chain' (DFC) in a typical terrestrial ecosystem?
A.The GFC is the major conduit for energy flow.
B.The DFC is the major conduit for energy flow.
C.Both contribute equally in all types of ecosystems.
D.The DFC is only present in aquatic ecosystems.
Download the worksheet for Ecosystem - Productivity and Decomposition to practice offline. It includes additional chapter-level practice questions.
Energy Flow and Food Chains
SubtopicEnergy Flow and Food Chains under Ecosystem for Grade 12 CBSE.
Preview questions (no answers)
- 1.
Which of the following organisms is a detritivore?
A.Lion
B.Earthworm
C.Eagle
D.Rabbit
- 2.
The movement of energy through various trophic levels is always unidirectional because:
A.Energy lost as heat cannot be reused by plants
B.Carnivores eat producers directly
C.Sunlight is available only during the day
D.Decomposers return energy to the sun
- 3.
In a pond ecosystem, what is the role of phytoplankton?
A.Decomposers
B.Primary consumers
C.Secondary consumers
D.Producers
- 4.
Which of the following is NOT a limitation of ecological pyramids?
A.They do not take into account the same species belonging to two or more trophic levels
B.They assume a simple food chain
C.Saprophytes are not given any place
D.They show the energy flow between levels
- 5.
Which level of the ecological pyramid contains the most energy in a stable forest ecosystem?
A.Top carnivores
B.Herbivores
C.Primary producers
D.Secondary consumers
- 6.
What is the primary reason why the oceans have low productivity compared to terrestrial ecosystems like tropical forests?
A.Lack of water
B.Low light penetration and nutrient limitation
C.Excessive number of consumers
D.High salinity prevents photosynthesis
- 7.
What describes the relationship between the biomass of a trophic level and the energy it contains?
A.Biomass and energy are unrelated
B.Lower biomass always contains higher energy
C.Usually, higher energy levels correspond to higher biomass levels in terrestrial ecosystems
D.Energy decreases but biomass always increases as we move up
- 8.
The total amount of living organic matter in an ecosystem at any time is called biomass. When expressed as dry weight, it is more accurate than fresh weight because:
A.Fresh weight contains water which is highly variable.
B.Dry weight includes the weight of minerals.
C.Fresh weight is difficult to measure in the field.
D.Dry weight measures the energy content directly.
- 9.
In the following diagram of a simplified ecosystem, what happens to the energy at the 'Decomposer' stage?
A.It is recycled back to the Sun.
B.It is entirely converted to biomass of producers.
C.It is released as heat and cannot be reused by the producers.
D.It increases as it moves to the next trophic level.
- 10.
If the efficiency of photosynthesis is and the incident solar radiation is , find the if the respiration loss is of .
A.B.C.D.
Download the worksheet for Ecosystem - Energy Flow and Food Chains to practice offline. It includes additional chapter-level practice questions.
Ecological Pyramids
SubtopicEcological Pyramids under Ecosystem for Grade 12 CBSE.
Preview questions (no answers)
- 1.
In an inverted pyramid of biomass, the producers are usually:
A.Very large trees
B.Small phytoplankton with high turnover rates
C.Large mammals
D.Small shrubs
- 2.
What is the primary source of energy for the first trophic level in most ecological pyramids?
A.Chemical energy
B.Solar energy
C.Geothermal energy
D.Mechanical energy
- 3.
Which of the following is NOT a level in an ecological pyramid?
A.Producers
B.Secondary consumers
C.Primary consumers
D.Secondary producers
- 4.
A peacock eats a snake which eats a frog which eats an insect which eats green plants. What is the trophic level of the peacock?
A.B.C.D. - 5.
Which of the following is represented by the pyramid of biomass in a grassland?
A.Total number of organisms at each level
B.Rate of energy flow at each level
C.Total dry weight of all living organisms at each level
D.The amount of inorganic nutrients at each level
- 6.
If the GPP of an ecosystem is and respiration loss is , what amount of energy is available as NPP for the first trophic level in an energy pyramid?
A.B.C.D. - 7.
Why is the energy flow in an ecosystem considered unidirectional?
A.Energy is recycled by decomposers
B.Energy cannot be passed back to the sun or a lower trophic level
C.Energy is produced by both consumers and producers
D.Higher trophic levels have more energy
- 8.
Which of the following factors is most responsible for the 'Inverted Pyramid of Biomass' in a pond, given that the Pyramid of Energy in the same pond is always upright?
A.The difference in longevity and turnover rates between phytoplankton and zooplankton.
B.The fact that zooplankton are much larger than phytoplankton.
C.The presence of decomposers at the bottom of the pond.
D.The low light penetration in deep water.
- 9.
In a hypothetical 'Pyramid of Energy', if a new level was added representing 'Total Incident Solar Radiation', what would be the approximate percentage of energy transfer from to (Producers)?
A.1-5%
B.10%
C.50%
D.90%
- 10.
If the 'Assimilation Efficiency' of a herbivore is and its 'Production Efficiency' (NSP/Assimilation) is , what percentage of the energy it consumes (Ingested Energy) is actually converted into new biomass available for the next trophic level?
A.3%
B.30%
C.10%
D.40%
Download the worksheet for Ecosystem - Ecological Pyramids to practice offline. It includes additional chapter-level practice questions.