UPSC Static Quiz – Environment : 5 April 2025
Kartavya Desk Staff
UPSC Static Quiz – Environment : 5 April 2025 We will post 5 questions daily on static topics mentioned in the UPSC civil services preliminary examination syllabus. Each week will focus on a specific topic from the syllabus, such as History of India and Indian National Movement, Indian and World Geography, and more.We are excited to bring you our daily UPSC Static Quiz, designed to help you prepare for the UPSC Civil Services Preliminary Examination. Each day, we will post 5 questions on static topics mentioned in the UPSC syllabus. This week, we are focusing on Indian and World Geography.
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• Question 1 of 5 1. Question What would happen if phytoplankton of an ocean is completely destroyed for some reason? The ocean as a carbon sink would be adversely affected. The density of ocean water would drastically increase. The food chains in the ocean would be adversely affected. How many of the above statements is/are correct? (a) Only one (b) Only two (c) All three (d) None Correct Solution: b) Statement 2 is incorrect. Phytoplankton play a critical role in ocean ecosystems and global biogeochemical cycles. As primary producers, they perform photosynthesis, absorbing large amounts of atmospheric carbon dioxide and contributing significantly to the ocean’s role as a carbon sink. Without phytoplankton, this carbon fixation process would be severely disrupted, leading to increased atmospheric CO₂ levels and weakening the ocean’s capacity to mitigate climate change—making statement 1 correct. Additionally, phytoplankton form the base of the marine food web. They serve as the primary food source for zooplankton, which in turn support higher trophic levels including small fish, large predators, and even whales. The removal of phytoplankton would thus lead to the collapse of marine food chains—statement 3 is also correct. However, statement 2 is incorrect. The destruction of phytoplankton would not drastically increase the density of ocean water. Ocean density is primarily influenced by temperature and salinity, not biological factors like phytoplankton biomass. Incorrect Solution: b) Statement 2 is incorrect. Phytoplankton play a critical role in ocean ecosystems and global biogeochemical cycles. As primary producers, they perform photosynthesis, absorbing large amounts of atmospheric carbon dioxide and contributing significantly to the ocean’s role as a carbon sink. Without phytoplankton, this carbon fixation process would be severely disrupted, leading to increased atmospheric CO₂ levels and weakening the ocean’s capacity to mitigate climate change—making statement 1 correct. Additionally, phytoplankton form the base of the marine food web. They serve as the primary food source for zooplankton, which in turn support higher trophic levels including small fish, large predators, and even whales. The removal of phytoplankton would thus lead to the collapse of marine food chains—statement 3 is also correct. However, statement 2 is incorrect. The destruction of phytoplankton would not drastically increase the density of ocean water. Ocean density is primarily influenced by temperature and salinity, not biological factors like phytoplankton biomass.
#### 1. Question
What would happen if phytoplankton of an ocean is completely destroyed for some reason?
• The ocean as a carbon sink would be adversely affected.
• The density of ocean water would drastically increase.
• The food chains in the ocean would be adversely affected.
How many of the above statements is/are correct?
• (a) Only one
• (b) Only two
• (c) All three
Solution: b)
Statement 2 is incorrect.
• Phytoplankton play a critical role in ocean ecosystems and global biogeochemical cycles. As primary producers, they perform photosynthesis, absorbing large amounts of atmospheric carbon dioxide and contributing significantly to the ocean’s role as a carbon sink. Without phytoplankton, this carbon fixation process would be severely disrupted, leading to increased atmospheric CO₂ levels and weakening the ocean’s capacity to mitigate climate change—making statement 1 correct.
• Additionally, phytoplankton form the base of the marine food web. They serve as the primary food source for zooplankton, which in turn support higher trophic levels including small fish, large predators, and even whales. The removal of phytoplankton would thus lead to the collapse of marine food chains—statement 3 is also correct.
• However, statement 2 is incorrect. The destruction of phytoplankton would not drastically increase the density of ocean water. Ocean density is primarily influenced by temperature and salinity, not biological factors like phytoplankton biomass.
Solution: b)
Statement 2 is incorrect.
• Phytoplankton play a critical role in ocean ecosystems and global biogeochemical cycles. As primary producers, they perform photosynthesis, absorbing large amounts of atmospheric carbon dioxide and contributing significantly to the ocean’s role as a carbon sink. Without phytoplankton, this carbon fixation process would be severely disrupted, leading to increased atmospheric CO₂ levels and weakening the ocean’s capacity to mitigate climate change—making statement 1 correct.
• Additionally, phytoplankton form the base of the marine food web. They serve as the primary food source for zooplankton, which in turn support higher trophic levels including small fish, large predators, and even whales. The removal of phytoplankton would thus lead to the collapse of marine food chains—statement 3 is also correct.
• However, statement 2 is incorrect. The destruction of phytoplankton would not drastically increase the density of ocean water. Ocean density is primarily influenced by temperature and salinity, not biological factors like phytoplankton biomass.
• Question 2 of 5 2. Question Consider the following statements regarding food chain in ecosystem. In an aquatic ecosystem, larger fraction of energy flow through detritus food chain than grazing food chain. In a terrestrial ecosystem, more energy flows through grazing food chain than detritus food chain. Around 90% of energy is lost in energy flow across different trophic levels. How many of the above statements is/are correct? a) Only one b) Only two c) All three d) None Correct Solution: a) Only Statement 3 is correct. In an aquatic ecosystem, grazing food chain is the major conduit for energy flow. As against this, in a terrestrial ecosystem, a much larger fraction of energy flows through the detritus food chain than through the grazing food chain. When energy is passed in an ecosystem from one trophic level to the next, only ten percent of the energy will be passed. Around 90% of energy will be lost. Incorrect Solution: a) Only Statement 3 is correct. In an aquatic ecosystem, grazing food chain is the major conduit for energy flow. As against this, in a terrestrial ecosystem, a much larger fraction of energy flows through the detritus food chain than through the grazing food chain. When energy is passed in an ecosystem from one trophic level to the next, only ten percent of the energy will be passed. Around 90% of energy will be lost.
#### 2. Question
Consider the following statements regarding food chain in ecosystem.
• In an aquatic ecosystem, larger fraction of energy flow through detritus food chain than grazing food chain.
• In a terrestrial ecosystem, more energy flows through grazing food chain than detritus food chain.
• Around 90% of energy is lost in energy flow across different trophic levels.
How many of the above statements is/are correct?
• a) Only one
• b) Only two
• c) All three
Solution: a)
Only Statement 3 is correct.
In an aquatic ecosystem, grazing food chain is the major conduit for energy flow. As against this, in a terrestrial ecosystem, a much larger fraction of energy flows through the detritus food chain than through the grazing food chain.
When energy is passed in an ecosystem from one trophic level to the next, only ten percent of the energy will be passed. Around 90% of energy will be lost.
Solution: a)
Only Statement 3 is correct.
In an aquatic ecosystem, grazing food chain is the major conduit for energy flow. As against this, in a terrestrial ecosystem, a much larger fraction of energy flows through the detritus food chain than through the grazing food chain.
When energy is passed in an ecosystem from one trophic level to the next, only ten percent of the energy will be passed. Around 90% of energy will be lost.
• Question 3 of 5 3. Question Which of the following play a role in the Nitrogen cycle on earth? Blue-green algae Lightning Uptake of soil nutrients by plants Terrestrial Food chain How many of the above options is/are correct? (a) Only one (b) Only two (c) Only three (d) All four Correct Solution: d) Nitrogen is one of the essential constituents of all living organisms as part of proteins, chlorophyll, nucleic acids and vitamins. The atmospheric nitrogen cannot be taken directly by plants and animals. Certain bacteria and blue green algae present in the soil fix nitrogen from the atmosphere and convert into compounds of nitrogen Lightning also fixes atmospheric nitrogen. Nitrogen is one of the essential constituents of all living organisms as part of proteins, chlorophyll, nucleic acids and vitamins. The atmospheric nitrogen cannot be taken directly by plants and animals. Once nitrogen is converted into these usable compounds, it can be utilised by plants from the soil through their root system. Nitrogen is then used for the synthesis of plant proteins and other compounds. Animals feeding on plants get these proteins and other nitrogen compounds. When plants and animals die, bacteria and fungi present in the soil convert the nitrogenous wastes into nitrogenous compounds to be used by plants again. Certain other bacteria convert some part of them to nitrogen gas which goes back into the atmosphere. As a result, the percentage of nitrogen in the atmosphere remains more or less constant. Incorrect Solution: d) Nitrogen is one of the essential constituents of all living organisms as part of proteins, chlorophyll, nucleic acids and vitamins. The atmospheric nitrogen cannot be taken directly by plants and animals. Certain bacteria and blue green algae present in the soil fix nitrogen from the atmosphere and convert into compounds of nitrogen Lightning also fixes atmospheric nitrogen. Nitrogen is one of the essential constituents of all living organisms as part of proteins, chlorophyll, nucleic acids and vitamins. The atmospheric nitrogen cannot be taken directly by plants and animals. Once nitrogen is converted into these usable compounds, it can be utilised by plants from the soil through their root system. Nitrogen is then used for the synthesis of plant proteins and other compounds. Animals feeding on plants get these proteins and other nitrogen compounds. When plants and animals die, bacteria and fungi present in the soil convert the nitrogenous wastes into nitrogenous compounds to be used by plants again. Certain other bacteria convert some part of them to nitrogen gas which goes back into the atmosphere. As a result, the percentage of nitrogen in the atmosphere remains more or less constant.
#### 3. Question
Which of the following play a role in the Nitrogen cycle on earth?
• Blue-green algae
• Uptake of soil nutrients by plants
• Terrestrial Food chain
How many of the above options is/are correct?
• (a) Only one
• (b) Only two
• (c) Only three
• (d) All four
Solution: d)
• Nitrogen is one of the essential constituents of all living organisms as part of proteins, chlorophyll, nucleic acids and vitamins.
• The atmospheric nitrogen cannot be taken directly by plants and animals.
• Certain bacteria and blue green algae present in the soil fix nitrogen from the atmosphere and convert into compounds of nitrogen
• Lightning also fixes atmospheric nitrogen.
• Nitrogen is one of the essential constituents of all living organisms as part of proteins, chlorophyll, nucleic acids and vitamins.
• The atmospheric nitrogen cannot be taken directly by plants and animals. Once nitrogen is converted into these usable compounds, it can be utilised by plants from the soil through their root system.
• Nitrogen is then used for the synthesis of plant proteins and other compounds. Animals feeding on plants get these proteins and other nitrogen compounds.
• When plants and animals die, bacteria and fungi present in the soil convert the nitrogenous wastes into nitrogenous compounds to be used by plants again. Certain other bacteria convert some part of them to nitrogen gas which goes back into the atmosphere.
• As a result, the percentage of nitrogen in the atmosphere remains more or less constant.
Solution: d)
• Nitrogen is one of the essential constituents of all living organisms as part of proteins, chlorophyll, nucleic acids and vitamins.
• The atmospheric nitrogen cannot be taken directly by plants and animals.
• Certain bacteria and blue green algae present in the soil fix nitrogen from the atmosphere and convert into compounds of nitrogen
• Lightning also fixes atmospheric nitrogen.
• Nitrogen is one of the essential constituents of all living organisms as part of proteins, chlorophyll, nucleic acids and vitamins.
• The atmospheric nitrogen cannot be taken directly by plants and animals. Once nitrogen is converted into these usable compounds, it can be utilised by plants from the soil through their root system.
• Nitrogen is then used for the synthesis of plant proteins and other compounds. Animals feeding on plants get these proteins and other nitrogen compounds.
• When plants and animals die, bacteria and fungi present in the soil convert the nitrogenous wastes into nitrogenous compounds to be used by plants again. Certain other bacteria convert some part of them to nitrogen gas which goes back into the atmosphere.
• As a result, the percentage of nitrogen in the atmosphere remains more or less constant.
• Question 4 of 5 4. Question The biological interaction between clownfish and sea anemones denotes a) Predation b) commensalism c) Amensalism d) Mutualism Correct Solution: d) Clownfish breed only in sea anemones, sharing a symbiotic bond. “It is a strong, obligate symbiosis,” “Clownfish shelter in the anemone and are the only fish that do not get stung by the nematocysts of the anemone. The anemone benefits because clownfish can defend the anemone from fish that might eat it. They never live anywhere but, in the anemone”. And now the anemones, like coral reefs in general, are under direct threat from the impacts of climate change. It works like this: The anemones share another symbiotic bond, with algae. Under stress in warming waters, the algae leave the anemones. If the algae stay away too long, the anemone starve to death, which leaves the clownfish without a home. Incorrect Solution: d) Clownfish breed only in sea anemones, sharing a symbiotic bond. “It is a strong, obligate symbiosis,” “Clownfish shelter in the anemone and are the only fish that do not get stung by the nematocysts of the anemone. The anemone benefits because clownfish can defend the anemone from fish that might eat it. They never live anywhere but, in the anemone”. And now the anemones, like coral reefs in general, are under direct threat from the impacts of climate change. It works like this: The anemones share another symbiotic bond, with algae. Under stress in warming waters, the algae leave the anemones. If the algae stay away too long, the anemone starve to death, which leaves the clownfish without a home.
#### 4. Question
The biological interaction between clownfish and sea anemones denotes
• a) Predation
• b) commensalism
• c) Amensalism
• d) Mutualism
Solution: d)
Clownfish breed only in sea anemones, sharing a symbiotic bond. “It is a strong, obligate symbiosis,”
“Clownfish shelter in the anemone and are the only fish that do not get stung by the nematocysts of the anemone. The anemone benefits because clownfish can defend the anemone from fish that might eat it. They never live anywhere but, in the anemone”.
And now the anemones, like coral reefs in general, are under direct threat from the impacts of climate change. It works like this: The anemones share another symbiotic bond, with algae. Under stress in warming waters, the algae leave the anemones. If the algae stay away too long, the anemone starve to death, which leaves the clownfish without a home.
Solution: d)
Clownfish breed only in sea anemones, sharing a symbiotic bond. “It is a strong, obligate symbiosis,”
“Clownfish shelter in the anemone and are the only fish that do not get stung by the nematocysts of the anemone. The anemone benefits because clownfish can defend the anemone from fish that might eat it. They never live anywhere but, in the anemone”.
And now the anemones, like coral reefs in general, are under direct threat from the impacts of climate change. It works like this: The anemones share another symbiotic bond, with algae. Under stress in warming waters, the algae leave the anemones. If the algae stay away too long, the anemone starve to death, which leaves the clownfish without a home.
• Question 5 of 5 5. Question Which one of the following is the best description of the term ‘standing crop’? a) It is the amount of biomass of a forest. b) It is the total amount of energy produced in a food chain. c) It is the total mass of living material at a particular time in an ecosystem. d) It is the number of primary producers in an ecosystem. Correct Solution: c) The term ‘standing crop’ refers to the total mass of living organisms present in a particular area of an ecosystem at a given point in time. This includes both the number and biomass (dry weight) of organisms at various trophic levels—producers, consumers, or decomposers—depending on the context of measurement. Unlike productivity, which is a rate (i.e., biomass produced per unit time), standing crop is a static measurement representing a snapshot of the ecosystem’s living material. It can be expressed in terms of biomass (e.g., kg/m²) or population density (e.g., individuals per unit area). For instance, the standing crop in a grassland may refer to the total dry mass of grasses at a particular time, or in a lake, it could be the total mass of fish or algae at a specific moment. It does not refer to energy flow or only primary producers. Incorrect Solution: c) The term ‘standing crop’ refers to the total mass of living organisms present in a particular area of an ecosystem at a given point in time. This includes both the number and biomass (dry weight) of organisms at various trophic levels—producers, consumers, or decomposers—depending on the context of measurement. Unlike productivity, which is a rate (i.e., biomass produced per unit time), standing crop is a static measurement representing a snapshot of the ecosystem’s living material. It can be expressed in terms of biomass (e.g., kg/m²) or population density (e.g., individuals per unit area). For instance, the standing crop in a grassland may refer to the total dry mass of grasses at a particular time, or in a lake, it could be the total mass of fish or algae at a specific moment. It does not refer to energy flow or only primary producers.
#### 5. Question
Which one of the following is the best description of the term ‘standing crop’?
• a) It is the amount of biomass of a forest.
• b) It is the total amount of energy produced in a food chain.
• c) It is the total mass of living material at a particular time in an ecosystem.
• d) It is the number of primary producers in an ecosystem.
Solution: c)
• The term ‘standing crop’ refers to the total mass of living organisms present in a particular area of an ecosystem at a given point in time. This includes both the number and biomass (dry weight) of organisms at various trophic levels—producers, consumers, or decomposers—depending on the context of measurement.
• Unlike productivity, which is a rate (i.e., biomass produced per unit time), standing crop is a static measurement representing a snapshot of the ecosystem’s living material.
• It can be expressed in terms of biomass (e.g., kg/m²) or population density (e.g., individuals per unit area). For instance, the standing crop in a grassland may refer to the total dry mass of grasses at a particular time, or in a lake, it could be the total mass of fish or algae at a specific moment. It does not refer to energy flow or only primary producers.
Solution: c)
• The term ‘standing crop’ refers to the total mass of living organisms present in a particular area of an ecosystem at a given point in time. This includes both the number and biomass (dry weight) of organisms at various trophic levels—producers, consumers, or decomposers—depending on the context of measurement.
• Unlike productivity, which is a rate (i.e., biomass produced per unit time), standing crop is a static measurement representing a snapshot of the ecosystem’s living material.
• It can be expressed in terms of biomass (e.g., kg/m²) or population density (e.g., individuals per unit area). For instance, the standing crop in a grassland may refer to the total dry mass of grasses at a particular time, or in a lake, it could be the total mass of fish or algae at a specific moment. It does not refer to energy flow or only primary producers.
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