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Q40 (IAS/2025) Environment & Ecology › Ecology & Ecosystem Basics › Biogeochemical cycles Answer Verified

With reference to the planet Earth, consider the following statements: 1. Rain forests produce more oxygen than that produced by oceans. 2. Marine phytoplankton and photosynthetic bacteria produce about 50% of world's oxygen. 3. Well-oxygenated surface water contains several folds higher oxygen than that in atmospheric air. Which of the statements given above is/are correct?

Result
Your answer: —  ·  Correct: B
Explanation

The correct answer is option B because only statement 2 is correct.

**Statement 1 is incorrect**: Phytoplankton produce more than 60% of oxygen produced from all plants[1], and nearly 50 percent of the global primary production takes place in the upper stratum of sea water[2]. This indicates that oceans (through phytoplankton) are major oxygen producers, not less than rainforests.

**Statement 2 is correct**: Phytoplankton produce more than 60% of oxygen produced from all plants[1], and nearly 50 percent of the global primary production takes place in the upper stratum of sea water[2]. Additionally, in the late Archean Eon, an oxygen-containing atmosphere began to develop, apparently produced by photosynthesising cyanobacteria[3]. These marine organisms together produce approximately 50% of the world's oxygen.

**Statement 3 is incorrect**: Well-oxygenated surface water does not contain several folds higher oxygen than atmospheric air. In fact, dissolved oxygen in water is measured in parts per million (ppm) or mg/L, which is far less than atmospheric oxygen concentration (approximately 21% or 210,000 ppm). The documents do not support the claim that water contains more oxygen than air.

Sources
  1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 14: Marine Organisms > 14.2 PHYTOPLANKTON > p. 207
  2. [2] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > 5.12. PLASTIG POLLUTION > p. 96
  3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Archean Eon (4000 mya – 2500 mya) > p. 270
How others answered
Each bar shows the % of students who chose that option. Green bar = correct answer, blue outline = your choice.
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PROVENANCE & STUDY PATTERN
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Don’t just practise – reverse-engineer the question. This panel shows where this PYQ came from (books / web), how the examiner broke it into hidden statements, and which nearby micro-concepts you were supposed to learn from it. Treat it like an autopsy of the question: what might have triggered it, which exact lines in the book matter, and what linked ideas you should carry forward to future questions.
Q. With reference to the planet Earth, consider the following statements: 1. Rain forests produce more oxygen than that produced by oceans.…
At a glance
Origin: Mixed / unclear origin Fairness: Low / Borderline fairness Books / CA: 3.3/10 · 0/10

This is a classic 'Myth-Buster' question. While popular media calls the Amazon the 'lungs of the Earth', standard ecology texts (Shankar/NCERT) clarify that oceans are the primary oxygen engine. Statement 3 is a basic General Science trap—confusing 'dissolved oxygen' (trace amounts) with 'atmospheric oxygen' (21%).

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
With reference to Earth, do terrestrial rainforests produce more oxygen than the Earth's oceans?
Origin: Weak / unclear Fairness: Borderline / guessy
Indirect textbook clues
Exploring Society:India and Beyond. Social Science-Class VI . NCERT(Revised ed 2025) > Chapter 2: Oceans and Continents > Oceans and Life > p. 38
Strength: 5/5
“instance, there would be no rainfall! The Earth would be a desert. Moreover, more than half of the world's oxygen is produced by the oceans' flora, which is why they are called 'the planet's lungs'. The oceans, therefore, play a crucial role in regulating the climate and sustaining life on Earth. Oceans have deeply impacted humanity in many other ways. From early times, people have used oceans and seas to migrate to other regions, to trade in all kinds of goods, to conduct military campaigns, and as a source of food through fishing. Oceans have also nourished the cultures of coastal people all over the world.”
Why relevant

States that more than half of the world's oxygen is produced by the oceans, labelling them the 'planet's lungs'.

How to extend

A student could compare this claim to estimates of oxygen production by terrestrial forests (e.g., rainforests) to judge which is larger.

Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > 2.4.3 Amazing microalgae: tiny helpers in water > p. 22
Strength: 5/5
“Microalgae are microscopic plant-like organisms that live in water, soil, air, and even on trees. They make their own food using sunlight. While doing this, they also release oxygen and produce more than half of the Earth's oxygen supply. They are rich in nutrients and serve as a food source for many aquatic animals. Some, like Spirulina, Chlorella, and Diatoms, are also used by humans as health supplements and medicines. Microalgae also help in cleaning water and are used to make biofuel. However, pollution, climate change, and habitat destruction are threatening microalgal diversity and abundance. It is important to conserve these tiny organisms to protect the environment and maintain oxygen balance on Earth.”
Why relevant

Says microalgae in water produce more than half of Earth's oxygen supply, highlighting the major role of microscopic marine photosynthesizers.

How to extend

A student could use this to infer that marine primary producers (not just trees) contribute substantially and compare their productivity per area to rainforest productivity.

Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > marine (sea/ocean) ecosystem > p. 28
Strength: 4/5
“Te basic functional mechanisms common to all ecosystems apply as much to the sea as to the land. But major diferences exist between the environmental conditions and life forms in the marine ecosystem and those of the terrestrial types. Oceans are the great body of saline water that covers 70.78 per cent of the surface area of the world. Tey support a total biomass, probably as much as ten times that on land. In many ways the marine environment is much more favourable to life than land areas; it is more equable, and the two most essential gases for life (oxygen and carbon dioxide) are readily available in water, provided it is not polluted.”
Why relevant

Notes oceans cover ~70.78% of Earth's surface and support total biomass possibly ten times that on land, implying a large capacity for photosynthesis.

How to extend

Combine ocean area and high marine biomass with per-area productivity data (from outside sources) to estimate total oceanic oxygen production versus forests.

FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 2: The Origin and Evolution of the Earth > Evolution of Atmosphere and Hydrosphere > p. 16
Strength: 3/5
“Life was confined to the oceans for a long time. Oceans began to have the contribution of oxygen through the process of photosynthesis. Eventually, oceans were saturated with oxygen, and 2,000 million years ago, oxygen began to flood the atmosphere.”
Why relevant

Explains that life (and oxygen production through photosynthesis) was long confined to the oceans and that oceans contributed oxygen to the atmosphere historically.

How to extend

Use this historical pattern to reason that oceans remain a primary oxygen source today and weigh that against terrestrial forest contributions.

Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Carbon and Oxygen Cycles > p. 19
Strength: 3/5
“Some of the elements combine gaseous and sedimentary cycles. Tese recycling processes are called biochemical cycles because they involve chemical reactions in both living and non-living systems. Tese two cycles have been considered together as they are closely intertwined through photosynthesis and respiration (Fig. 1.8). Te atmosphere is the principal reserve of available oxygen. Large reserves of oxygen exist in Earth's crust, but they are unavailable as it is chemically bound to other elements. As for carbon, the greatest pool is in the ocean—about 39,000 billion tons, or about 93 per cent of Earth's total carbon. However, all of this carbon is bound chemically in carbon dioxide.”
Why relevant

Describes the atmosphere as the principal reserve of available oxygen and highlights the ocean as Earth's major carbon pool, linking oceans to major biogeochemical cycles.

How to extend

A student could infer that large carbon/stored nutrient pools in oceans support extensive photosynthetic communities, then compare expected oxygen fluxes with those from rainforests.

Statement 2
With reference to Earth, what percentage of the world's oxygen is produced by marine phytoplankton and photosynthetic bacteria?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 14: Marine Organisms > 14.2 PHYTOPLANKTON > p. 207
Presence: 5/5
“• Derived from the Greek words phyto (plant) and plankton (made to wander or drift), phytoplankton are microscopic plant organisms that live in aquatic environments, both salty and fresh. • Some phytoplankton are bacteria, some are protists, and most are single-celled plants. Among the common kinds are cyanobacteria, silica-encased diatoms, dinoflagellates, green algae, and chalk-coated coccolithophores. • Phytoplankton produce more than 60% of oxygen produced from all plants. All phytoplankton photosynthesize, but some get additional energy by consuming other organisms. • These micro-algae are present throughout the lighted regions of all the seas and oceans, including the Polar Regions.• Their total biomass is many times greater than that of the total plants on land, and they serve as the "pasture grounds" in the aquatic environment.”
Why this source?
  • Explicitly states phytoplankton produce more than 60% of the oxygen produced from all plants.
  • Notes that some phytoplankton are bacteria (including cyanobacteria), so photosynthetic bacteria are included in this group.
  • Locates phytoplankton throughout the lighted regions of the seas and oceans, implying a global-scale contribution.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > 5.12. PLASTIG POLLUTION > p. 96
Presence: 3/5
“The marine resource covering 70 percent of, the earth's surface is a key asset in the biosphere. Of the nearly r.5 million species known, nearly a quarter million live in the world's oceans. More importantly, nearly 50 percent of the global primary production takes place in the upper stratum of sea water. Seafood presently represents 30% of the protein in global diet, The health of the marine food web and the fisheries resources invariably depend upon the long-term viability of the autotrophic aigae (phytoplankton * primary producer) and the zooplankton (primary consumers) in the marine food pyramid. Plastics represent the latest contaminant in the marine environment; the increased use of plastics has led to negative environmental impacts.”
Why this source?
  • Reports that nearly 50% of global primary production occurs in the upper sea, supporting a large marine contribution to global oxygen production.
  • Links marine primary production to the base of the marine food web, reinforcing the ecological scale of phytoplankton productivity.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Archean Eon (4000 mya – 2500 mya) > p. 270
Presence: 3/5
“• The atmosphere was without oxygen, and the atmospheric pressure was around 10 to 100 atmospheres. Nitrogen formed a major part of the then stable "second atmosphere". Most of the nitrogen in the air was carried out from deep inside the earth by volcanoes.• In the late Archean Eon, an oxygen-containing atmosphere began to develop, apparently produced by photosynthesising cyanobacteria.”
Why this source?
  • Describes cyanobacteria (photosynthetic bacteria) as producers of oxygen in Earth's early atmosphere, showing the role of photosynthetic bacteria in oxygen generation.
  • Provides taxonomic/functional support that photosynthetic bacteria are agents of oxygen production over geological timescales.
Statement 3
With reference to Earth, do well-oxygenated surface waters contain several times higher oxygen concentrations than atmospheric air?
Origin: Weak / unclear Fairness: Borderline / guessy
Indirect textbook clues
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 4: Aquatic Ecosystem > Dissolved oxygen: > p. 34
Strength: 5/5
“• o In aquatic ecosystems oxygen is dissolved in water, i.r., here its concentration varies constantly depending on factors that influence the input and output of oxygen in water. • r In fresh water the average concentration of dissolved oxygen is 0. 01 per cent (also expressed as 10 parts per million or 10 ppm) by weight, which is 50 times lower than the concentration of oxygen in an equivalent volume of air. Other linear factors which influence on aquatic productivity are mffi All Rights Reserved. No part of this material mav be reproduced in anv form or b1 an1' means, without permlssion in l.riting,”
Why relevant

Gives a numeric estimate for dissolved oxygen in fresh water (≈10 ppm by weight) and explicitly compares it to the concentration of oxygen in an equivalent volume of air (stating it is ~50 times lower).

How to extend

A student could combine this ratio with the known percent composition of atmospheric oxygen to convert units (ppm in water vs % in air or mg/L vs partial pressure) using basic gas–liquid solubility ideas to judge the claim.

Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > 20.1. Composition of The Earth's Atmosphere > p. 270
Strength: 5/5
“• The composition of Earth's atmosphere is largely governed by the by-products of the life it sustains. Dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon and traces of hydrogen, helium, and other noble gases. The remaining gases are often referred to as trace gases, among which are the greenhouse gases, principally carbon dioxide (0.036%), methane, nitrous oxide, and ozone.• Various industrial pollutants also may be present as gases or aerosols, such as chlorine, fluorine compounds and elemental mercury vapour. Sulphur compounds such as hydrogen sulphide (H2S) and sulphur dioxide (SO2) may be derived from natural sources or industrial air pollution.”
Why relevant

States the composition of dry air, including that oxygen is ~20.95% of the atmosphere, providing the atmospheric concentration baseline for comparison.

How to extend

A student can use 21% O2 as the atmospheric reference and, with a dissolved-O2 value (e.g., from snippet 1), compare magnitudes after converting units.

Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Phanerozoic Eon (541 mya to Present): The Present Atmosphere > p. 271
Strength: 4/5
“• The amount of oxygen peaked at about 30% around 280 million years ago. This period with more oxygen is associated with the rapid development of animals. Today's atmosphere contains 21% oxygen, which is great enough for this rapid development of animals.• Two main processes govern changes in the oxygen levels in the atmosphere: • 1. Plants use carbon dioxide from the atmosphere, releasing oxygen.• 2. Breakdown of pyrite (iron sulphide) and volcanic eruptions release sulphur into the atmosphere, which oxidises and hence reduces the amount of oxygen in the atmosphere. However, volcanic eruptions also release carbon dioxide, which plants can convert to oxygen.”
Why relevant

Also cites today's atmosphere containing 21% oxygen, reinforcing the atmospheric O2 baseline and indicating its biological importance.

How to extend

Use this repeated atmospheric O2 fraction together with dissolved-O2 numbers to assess whether water can have 'several times higher' O2 than air when compared in commensurate units.

Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.6 > p. 89
Strength: 4/5
“Fishes take in water through their mouths and force it past the gills where the dissolved oxygen is taken up by blood. Terrestrial organisms use the oxygen in the atmosphere for respiration. This oxygen is absorbed by different organs in different animals. All these organs have a structure that increases the surface area which is in contact with the oxygen-rich atmosphere. Since the exchange of oxygen and carbon dioxide has to take place across this surface, this surface is very fine and delicate. In order to protect this surface, it is usually placed within the body, so there have to be passages that will take air to this area.”
Why relevant

Distinguishes that aquatic animals take up dissolved oxygen from water while terrestrial animals use atmospheric oxygen, highlighting that oxygen exists in different phases and must be compared accordingly.

How to extend

A student could use this phase distinction to remember that direct numeric comparison requires unit conversion (concentration in water vs concentration/partial pressure in air) and consider equilibria (Henry’s law) when judging the statement.

Pattern takeaway: UPSC loves to penalize 'Pop-Science' knowledge. If a statement validates a common WhatsApp forward (like 'Rainforests produce all our oxygen'), be skeptical. They also test the *magnitude* of physical constants (ppm vs %) to trap students who ignore units.
How you should have studied
  1. [THE VERDICT]: Conceptual Sitter. Directly solvable using Shankar IAS (Chapter 14) and basic NCERT Science logic.
  2. [THE CONCEPTUAL TRIGGER]: Biogeochemical Cycles (Oxygen Cycle) and Marine Productivity.
  3. [THE HORIZONTAL EXPANSION]: Memorize NPP (Net Primary Productivity) rankings: Estuaries/Swamps > Rainforests > Oceans (per unit area), but Oceans > Rainforests (Total Global Production due to vast area). Understand 'Compensation Depth' (where photosynthesis = respiration). Know the 'Great Oxidation Event' caused by Cyanobacteria.
  4. [THE STRATEGIC METACOGNITION]: Stop compartmentalizing. This question required merging Geography (Ocean area), Biology (Phytoplankton function), and Chemistry (Gas solubility). When reading about 'Dissolved Oxygen' in pollution chapters, note the unit (ppm) vs Air (percentage) to catch the magnitude difference.
Concept hooks from this question
📌 Adjacent topic to master
S1
👉 Marine phytoplankton and microalgae as primary oxygen producers
💡 The insight

Marine microalgae and phytoplankton produce more than half of Earth's oxygen and are key drivers of global oxygen supply.

High-yield for questions on biosphere functioning, primary productivity and ecosystem services; connects to topics on marine ecology, climate regulation and human dependence on oceanic life. Mastery enables answering questions on sources of atmospheric oxygen and the ecological importance of tiny aquatic organisms.

📚 Reading List :
  • Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > 2.4.3 Amazing microalgae: tiny helpers in water > p. 22
  • Exploring Society:India and Beyond. Social Science-Class VI . NCERT(Revised ed 2025) > Chapter 2: Oceans and Continents > Oceans and Life > p. 38
🔗 Anchor: "With reference to Earth, do terrestrial rainforests produce more oxygen than the..."
📌 Adjacent topic to master
S1
👉 Relative biomass and productivity: oceans versus land
💡 The insight

The oceans support much greater total biomass and provide more favourable conditions for life than terrestrial environments, implying higher overall biological productivity than land ecosystems.

Useful for exam items comparing global biomass, primary productivity and ecological carrying capacity; links to resource management, conservation priority setting and carbon sequestration debates. Understanding this helps evaluate claims that terrestrial forests outproduce oceans in oxygen generation.

📚 Reading List :
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > marine (sea/ocean) ecosystem > p. 28
  • Exploring Society:India and Beyond. Social Science-Class VI . NCERT(Revised ed 2025) > Chapter 2: Oceans and Continents > Oceans and Life > p. 38
🔗 Anchor: "With reference to Earth, do terrestrial rainforests produce more oxygen than the..."
📌 Adjacent topic to master
S1
👉 Oxygen and carbon reservoirs and their cycles
💡 The insight

The atmosphere is the principal available oxygen reservoir while the ocean contains the largest share of Earth's carbon, tying oxygen production tightly to biogeochemical cycles.

Crucial for questions on biogeochemical cycles, climate change and carbon budgeting; connects ecology with Earth history and atmospheric composition. Grasping these cycles helps analyze long-term oxygen sources and sinks and policy implications for emissions and conservation.

📚 Reading List :
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Carbon and Oxygen Cycles > p. 19
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 2: The Origin and Evolution of the Earth > Evolution of Atmosphere and Hydrosphere > p. 16
🔗 Anchor: "With reference to Earth, do terrestrial rainforests produce more oxygen than the..."
📌 Adjacent topic to master
S2
👉 Phytoplankton as oceanic primary producers
💡 The insight

Phytoplankton form the dominant microscopic vegetation in oceans and produce the majority of plant-derived oxygen on Earth.

High-yield for ecology and geography questions: explains the basis of marine primary productivity, links to fisheries and carbon cycling, and is often tested in questions on global oxygen sources and biosphere functioning.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 14: Marine Organisms > 14.2 PHYTOPLANKTON > p. 207
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > Plant Life in a marine ecosystem > p. 29
🔗 Anchor: "With reference to Earth, what percentage of the world's oxygen is produced by ma..."
📌 Adjacent topic to master
S2
👉 Cyanobacteria and photosynthetic bacteria in oxygen generation
💡 The insight

Photosynthetic bacteria (cyanobacteria) are part of phytoplankton and have been key producers of oxygen both historically and in modern marine systems.

Vital for questions on Earth's atmospheric evolution, biogeochemical cycles, and microbial contributions to primary production; connects history (Great Oxygenation) with present-day marine ecology.

📚 Reading List :
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Archean Eon (4000 mya – 2500 mya) > p. 270
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 14: Marine Organisms > 14.2 PHYTOPLANKTON > p. 207
🔗 Anchor: "With reference to Earth, what percentage of the world's oxygen is produced by ma..."
📌 Adjacent topic to master
S2
👉 Euphotic (photic) zone controls marine productivity
💡 The insight

Marine primary producers (phytoplankton) are confined to the euphotic zone, which constrains where oxygen-producing photosynthesis occurs in the ocean.

Important for understanding spatial limits of ocean productivity, nutrient dynamics, and regional differences in oxygen/carbon fluxes; helps answer questions on why productivity varies across oceans and its policy/ecosystem implications.

📚 Reading List :
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 33: Ocean temperature and salinity > How Do Deep Water Marine Organisms Survive In Spite Of The Absence Of Sunlight? > p. 511
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > Plant Life in a marine ecosystem > p. 29
🔗 Anchor: "With reference to Earth, what percentage of the world's oxygen is produced by ma..."
📌 Adjacent topic to master
S3
👉 Dissolved oxygen in freshwater (DO) and its magnitude
💡 The insight

Dissolved oxygen in freshwater is measured in parts per million and is much lower than oxygen concentration in air, so DO values are the correct basis for comparing oxygen availability in water versus atmosphere.

High-yield for questions comparing atmospheric and aquatic respiration, aquatic ecosystem health, and water quality; connects biology (fish respiration) with environmental monitoring and pollution topics. Mastery helps answer comparative numeric and conceptual questions on oxygen availability across media.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 4: Aquatic Ecosystem > Dissolved oxygen: > p. 34
  • Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.6 > p. 89
🔗 Anchor: "With reference to Earth, do well-oxygenated surface waters contain several times..."
🌑 The Hidden Trap

The 'Biological Pump'. Since UPSC asked about oxygen production, the next logical question is carbon sequestration. Phytoplankton absorb CO2 and sink, storing carbon in the deep ocean. Also, look out for 'Prochlorococcus'—the specific cyanobacteria responsible for ~20% of global oxygen, likely the next specific term to be tested.

⚡ Elimination Cheat Code

Apply 'Physiological Common Sense' to Statement 3. Air is ~21% Oxygen. If water had 'several folds higher' (e.g., 3x = 63%), it would be a highly reactive chemical soup, not water. Also, if water had more oxygen than air, why do fish need gills with massive surface area to extract it, while humans breathe easily? The struggle of aquatic life suggests oxygen is scarce in water, not abundant. Eliminate 3.

🔗 Mains Connection

Connect Marine Oxygen to 'Ocean Deoxygenation' (a Mains GS-3 Environment topic). Warming oceans hold less oxygen (Henry's Law), creating 'Dead Zones'. This links directly to Food Security (Fisheries collapse) and Blue Economy policies.

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SIMILAR QUESTIONS

IAS · 2021 · Q72 Relevance score: 3.39

With reference to the water on the planet Earth, consider the following statements : 1. The amount of water in the rivers and lakes is more than the amount of groundwater. 2. The amount of water in polar ice caps and glaciers is more than the amount of groundwater. Which of the statements given above is/are correct?

IAS · 2010 · Q102 Relevance score: 1.94

Consider the following statements: 1. On the planet Earth, the fresh water available for use amounts to about less than 1% of the total water found. 2. Of the total fresh water found on the planet Earth 95% is bound up in polar ice caps and glaciers. Which of the statements given above is/are correct?

IAS · 2023 · Q63 Relevance score: 1.67

Consider the following statements : Statement-I : The soil in tropical rain forests is rich in nutrients. Statement-II : The high temperature and moisture of tropical rain forests cause dead organic matter in the soil to decompose quickly. Which one of the following is correct in respect of the above statements?

IAS · 2024 · Q7 Relevance score: 1.11

Consider the following statements : Statement-I : Rainfall is one of the reasons for weathering of rocks. Statement-II : Rain water contains carbon dioxide in solution. Statement-III : Rain water contains atmospheric oxygen. Which one of the following is correct in respect of the above statements ?

IAS · 2023 · Q64 Relevance score: 0.97

Consider the following statements : Statement-I : The temperature contrast between continents and oceans is greater during summer than in winter. Statement-II : The specific heat of water is more than that of land surface. Which one of the following is correct in respect of the above statements?