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Q30 (IAS/2021) Environment & Ecology › Ecology & Ecosystem Basics › Ecological succession Official Key

In the nature, which of the following is/are most likely to be found surviving on a surface without soil? 1. Fern 2. Lichen 3. Moss 4. Mushroom Select the correct answer using the code given below.

Result
Your answer: —  ·  Correct: C
Explanation

The correct answer is Option 3 (2 and 3) because Lichens and Mosses are pioneer species in primary ecological succession.

  • Lichens (2): These are symbiotic associations between algae and fungi. They secrete organic acids that weather rocks, breaking them down into smaller particles, allowing them to survive on bare rocky surfaces without soil.
  • Mosses (3): As bryophytes, mosses lack true roots and instead use rhizoids for attachment. They can grow on damp rocks or tree bark, requiring very little substrate, and often follow lichens in the succession process.
  • Ferns (1): These are vascular plants that generally require well-developed soil to anchor their root systems and absorb nutrients.
  • Mushrooms (4): Being saprophytic fungi, they require organic matter (like decaying wood or humus-rich soil) to thrive; they cannot survive on a bare, inorganic surface like a rock.

Thus, only Lichens and Mosses possess the physiological adaptations to colonize and survive on surfaces devoid of soil.

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Q. In the nature, which of the following is/are most likely to be found surviving on a surface without soil? 1. Fern 2. Lichen 3. Moss 4. Mu…
At a glance
Origin: From standard books Fairness: High fairness Books / CA: 10/10 · 0/10

This is a classic 'Ecological Succession' question disguised as a general observation query. While ferns (epiphytes) and mushrooms (wood-rotters) technically don't need mineral soil, Lichens and Mosses are the textbook 'Pioneer Species' cited in every NCERT and Geography book for colonizing bare rock. The key is identifying the primary context: Pedogenesis and Succession.

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
Can ferns survive and grow on a surface without soil, such as on bare rock or as epiphytes on tree bark?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 1. Tropical Evergreen Rainforest Biome > p. 7
Presence: 5/5
“such as orchids, bromeliads and fern that live entirely above ground, supported physically but not nutritionally by the structures of other plants are epiphytes. Epiphytes plants attach themselves to the trunk, branches or foliage of trees and lianas. Teir 'host' is used solely as a means of physical support. Epiphytes include plants of many diferent types – ferns, orchids, mosses, and lichens. Undergrowth is restricted in many areas by the shortage of sunlight at ground level. Tese epiphytes provide certain habitats to microorganisms, such as snails, centipedes, termites, earthworms, lizards, tree-frogs, ants, tse-tse fies, mosquitos, and numerous insects. Te main animals include numerous birds, bats, falconet, swifts, parakeets, barbets, monkeys, squirrels, peacocks, bill-bird and fowls.”
Why this source?
  • Explicitly lists ferns among epiphytes that live above ground and are supported physically but not nutritionally by other plants.
  • States epiphytes attach to trunks, branches or foliage, showing ferns can grow on tree surfaces without soil.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Equatorial Vegetation > p. 426
Presence: 5/5
“All plants struggle upwards (most epiphytes) for sunlight resulting in a peculiar layer arrangement. • Epiphyte: An epiphyte is a plant that grows harmlessly upon another plant (such as a tree) and derives its moisture and nutrients from the air, rain, and sometimes from debris accumulating around it.• The equatorial vegetation comprises a multitude of evergreen trees that yield tropical hardwood, e.g. mahogany, ebony, dyewoods etc. In the coastal areas and brackish swamps, mangrove forests thrive. Many parts of the tropical rain forests have been cleared for either lumbering or shifting cultivation. Despite dense forests, countries in equatorial regions are net timber importers.”
Why this source?
  • Provides a definition of epiphyte and says they derive moisture and nutrients from air, rain and accumulated debris rather than from soil.
  • Places the epiphytic habit in forest canopies, supporting the idea that ferns can survive on bark/branches.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Biological Activity and Weathering > p. 91
Presence: 3/5
“• Biological weathering is the removal of minerals from the environment due to the growth or movement of organisms.• Living organisms contribute to both mechanical and chemical weathering.• Lichens and mosses grow on essentially bare rock surfaces and create a more humid chemical microenvironment.• On a larger scale, seedlings sprouting in a crevice and plant roots exert physical pressure and provide a pathway for water and chemical infiltration.• Burrowing and wedging by organisms like earthworms, rodents etc., help expose the new surfaces to chemical attack and assist in the penetration of moisture and air.”
Why this source?
  • Describes lichens and mosses growing on essentially bare rock and creating humid microenvironments.
  • Notes seedlings sprouting in crevices and roots penetrating rock, implying vascular plants can establish on rock after pioneer colonisation.
Statement 2
Can lichens survive and grow on a surface without soil, such as on bare rock or tree bark?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 4: Weathering, Mass Movement and Groundwater > CHEMICAL WEATHERING > p. 37
Presence: 5/5
“3. Decomposition by organic acids. Within the soil which covers most rocks are bacteria which thrive on decaying plant or animal material. These bacteria produce acids which, when dissolved in water, help to speed up the weathering of the underlying rocks. In some cases, micro-organisms and plants like mosses or lichens can live on bare rock, so long as the surface is damp. These absorb chemical elements from the rocks as food and also produce organic acids.”
Why this source?
  • Explicitly notes lichens can live on bare rock provided the surface is damp
  • Explains lichens absorb elements from rock and produce organic acids, enabling growth on non-soil surfaces
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Biological Activity and Weathering > p. 91
Presence: 5/5
“• Biological weathering is the removal of minerals from the environment due to the growth or movement of organisms.• Living organisms contribute to both mechanical and chemical weathering.• Lichens and mosses grow on essentially bare rock surfaces and create a more humid chemical microenvironment.• On a larger scale, seedlings sprouting in a crevice and plant roots exert physical pressure and provide a pathway for water and chemical infiltration.• Burrowing and wedging by organisms like earthworms, rodents etc., help expose the new surfaces to chemical attack and assist in the penetration of moisture and air.”
Why this source?
  • States lichens grow on essentially bare rock surfaces
  • Explains lichens create a more humid microenvironment that supports their growth on rock
Science-Class VII . NCERT(Revised ed 2025) > Chapter 2: Exploring Substances: Acidic, Basic, and Neutral > HOLISTIC LENS > p. 10
Presence: 4/5
“Lichens are formed by the association of two living organisms, a fungus and an alga. They grow on rocks and trees in regions that have abundant rainfall and clean air. Do you fi nd lichens on trees in your neighbourhood? Lichens Now, let us classify the substances sorted in Group A, Group B, and Group C in Table 2.2. • The substances in Group A, such as lemon juice, amla juice, tamarind water, and vinegar turned the blue litmus paper to red, implying that these substances are acidic in nature.• The substances in Group B, such as soap solution, baking soda solution, lime water, and washing powder solution turned the red litmus paper to blue.”
Why this source?
  • Defines lichens as a fungus–alga association and notes they grow on rocks and trees
  • Links their occurrence to regions with abundant rainfall and clean air, supporting non-soil growth
Statement 3
Can mosses survive and grow on a surface without soil, such as on bare rock or tree bark?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 4: Weathering, Mass Movement and Groundwater > CHEMICAL WEATHERING > p. 37
Presence: 5/5
“3. Decomposition by organic acids. Within the soil which covers most rocks are bacteria which thrive on decaying plant or animal material. These bacteria produce acids which, when dissolved in water, help to speed up the weathering of the underlying rocks. In some cases, micro-organisms and plants like mosses or lichens can live on bare rock, so long as the surface is damp. These absorb chemical elements from the rocks as food and also produce organic acids.”
Why this source?
  • Explicitly states mosses (and lichens) can live on bare rock when the surface is damp.
  • Notes they absorb chemical elements from rocks and produce organic acids, supporting nutrition and survival without soil.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Biological Activity and Weathering > p. 91
Presence: 5/5
“• Biological weathering is the removal of minerals from the environment due to the growth or movement of organisms.• Living organisms contribute to both mechanical and chemical weathering.• Lichens and mosses grow on essentially bare rock surfaces and create a more humid chemical microenvironment.• On a larger scale, seedlings sprouting in a crevice and plant roots exert physical pressure and provide a pathway for water and chemical infiltration.• Burrowing and wedging by organisms like earthworms, rodents etc., help expose the new surfaces to chemical attack and assist in the penetration of moisture and air.”
Why this source?
  • Says lichens and mosses grow on essentially bare rock surfaces.
  • Explains they create a more humid chemical microenvironment that aids their growth on non-soil substrates.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 9: Indian Biodiversity Diverse Landscape > 5. Bryophytes \ > p. 157
Presence: 3/5
“The plant body is differentiated into a small stem and simple leaves, but true roots are absent. They usually grow in moist places. E.g. Liverworts, mosses They are the second largest group of green plants in India, distributed largely in Eastern Himalaya, Northeastern India, Western Himalaya and the Western Ghats. Mosses constitute the major component of Indian bryoflora followed by liverworts and hornworts.”
Why this source?
  • Describes bryophytes (including mosses) as lacking true roots, implying they do not require soil-root systems.
  • Notes they usually grow in moist places, consistent with survival on damp rock or bark surfaces.
Statement 4
Can mushrooms (fungal fruiting bodies or their mycelia) survive and grow on surfaces without soil, such as on decaying wood or rock?
Origin: Direct from books Fairness: Straightforward Book-answerable
From standard books
Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 12: How Nature Works in Harmony > 12.6 What Happens to Waste in Nature? > p. 200
Presence: 5/5
“You may have seen small umbrella-like structures, mushrooms, growing on dead plants or trees during the rainy season (Fig. 12.12). These are a type of fungi that grow on dead matter. Microorganisms like fungi and bacteria break down complex substances in dead plants and animals into simpler ones. This process returns”
Why this source?
  • Directly notes mushrooms growing on dead plants or trees (rainy season) — a clear example of growth on decaying organic surfaces.
  • Links mushrooms to decomposition activity, showing they colonize non-soil organic substrates such as wood.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 9: Indian Biodiversity Diverse Landscape > 2. Fungi: > p. 156
Presence: 5/5
“Non-green, non-differentiated plants characterised by total absence of chlorophyll are called Fungi. They grow either on dead, rotten organic matters as saprophytes or live as parasites on other living bodies, which are referred to as hosts. Moulds and mushrooms are the familiar examples of saprophytic fungi. The maximum diversity of fungi is in the Western Ghats, followed by the eastern Himalaya and the western Himalaya.”
Why this source?
  • Defines fungi (including mushrooms) as saprophytes that grow on dead, rotten organic matter, which includes decaying wood.
  • Specifically names mushrooms and moulds as familiar saprophytic examples, supporting survival on non-soil organic substrates.
Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 4: Weathering, Mass Movement and Groundwater > CHEMICAL WEATHERING > p. 37
Presence: 4/5
“3. Decomposition by organic acids. Within the soil which covers most rocks are bacteria which thrive on decaying plant or animal material. These bacteria produce acids which, when dissolved in water, help to speed up the weathering of the underlying rocks. In some cases, micro-organisms and plants like mosses or lichens can live on bare rock, so long as the surface is damp. These absorb chemical elements from the rocks as food and also produce organic acids.”
Why this source?
  • States that organisms like mosses or lichens can live on bare rock if the surface is damp; lichens include fungal partners.
  • Describes uptake of elements from rock and production of organic acids, indicating metabolic activity and growth on non-soil rock surfaces.
Pattern takeaway: UPSC tests 'Functional Ecology' over 'Botanical Trivia'. The question wasn't asking for exceptions (like hydroponic ferns); it was asking for the fundamental rule of nature regarding who colonizes barren land first.
How you should have studied
  1. [THE VERDICT]: Sitter. Directly sourced from NCERT Class VII/VIII Science and GC Leong (Weathering/Succession chapters).
  2. [THE CONCEPTUAL TRIGGER]: Ecological Succession (specifically Lithosere - succession on bare rock) and Biological Weathering.
  3. [THE HORIZONTAL EXPANSION]: Memorize the Lithosere sequence: Crustose Lichen → Foliose Lichen → Mosses → Herbs → Shrubs. Distinguish 'Epiphytes' (Ferns/Orchids - need physical support/humus) from 'Saprophytes' (Mushrooms - need dead organic carbon) and 'Lithophytes' (Rock dwellers). Note that Lichens are SO2 pollution indicators.
  4. [THE STRATEGIC METACOGNITION]: Do not study organisms in isolation; study them by their *functional role* (Pioneer vs. Decomposer). The examiner framed this to test if you know who starts the life cycle on a barren surface (rock), not just who can hang off a tree.
Concept hooks from this question
📌 Adjacent topic to master
S1
👉 Epiphytes and non-soil nutrient acquisition
💡 The insight

Epiphytic plants, including ferns, obtain moisture and nutrients from air, rain and accumulated debris rather than soil.

High-yield for questions on plant adaptations and forest ecology; links plant functional types to vertical stratification in forests and biodiversity topics; helps answer canopy ecology and species-interaction questions.

📚 Reading List :
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 1. Tropical Evergreen Rainforest Biome > p. 7
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Equatorial Vegetation > p. 426
🔗 Anchor: "Can ferns survive and grow on a surface without soil, such as on bare rock or as..."
📌 Adjacent topic to master
S1
👉 Primary succession on bare rock (pioneer colonisers)
💡 The insight

Bare rock surfaces undergo primary succession beginning with pioneer communities that prepare the substrate for later plants.

Essential for questions on ecosystem succession and soil formation; connects geomorphology with vegetation dynamics and is useful for scenarios about glacial retreat, lava flows, or disturbed land recovery.

📚 Reading List :
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Terrestrial Succession > p. 28
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Biological Activity and Weathering > p. 91
🔗 Anchor: "Can ferns survive and grow on a surface without soil, such as on bare rock or as..."
📌 Adjacent topic to master
S1
👉 Biological weathering and microhabitat formation by bryophytes/lichens
💡 The insight

Lichens and mosses chemically and physically alter rock surfaces and create humid microenvironments that facilitate subsequent plant establishment.

Important for integrated questions on weathering, biotic influences on landforms, and soil genesis; enables answers that link biological activity to physical geography and later successional stages.

📚 Reading List :
  • Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 4: Weathering, Mass Movement and Groundwater > CHEMICAL WEATHERING > p. 37
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Biological Activity and Weathering > p. 91
🔗 Anchor: "Can ferns survive and grow on a surface without soil, such as on bare rock or as..."
📌 Adjacent topic to master
S2
👉 Lichen symbiosis (fungus + alga)
💡 The insight

Lichens are mutualistic associations of a fungus and an alga, enabling photosynthesis and moisture retention on non-soil substrates.

High-yield for ecological and biological questions: explains how composite organisms adapt to harsh substrates, links to adaptation and interspecific interactions, and supports questions on organismal roles in ecosystems.

📚 Reading List :
  • Science-Class VII . NCERT(Revised ed 2025) > Chapter 2: Exploring Substances: Acidic, Basic, and Neutral > HOLISTIC LENS > p. 10
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 9: Indian Biodiversity Diverse Landscape > 4. Lichens > p. 157
🔗 Anchor: "Can lichens survive and grow on a surface without soil, such as on bare rock or ..."
📌 Adjacent topic to master
S2
👉 Pioneer species & biological weathering/soil formation
💡 The insight

Lichens colonize bare rock, produce organic acids and trap moisture, initiating weathering and the accumulation of material that leads to soil formation.

Crucial for physical geography and ecology: explains primary succession, genesis of regolith and soil, and biotic contributions to landscape evolution; useful for questions on succession sequences and soil formation processes.

📚 Reading List :
  • Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 4: Weathering, Mass Movement and Groundwater > CHEMICAL WEATHERING > p. 37
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Terrestrial Succession > p. 28
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 5: Geomorphic Processes > Process of Soil Formation > p. 44
🔗 Anchor: "Can lichens survive and grow on a surface without soil, such as on bare rock or ..."
📌 Adjacent topic to master
S2
👉 Moisture and air-quality dependence for lichen growth
💡 The insight

Lichen establishment on rock or bark is favoured by damp surfaces or abundant rainfall and by relatively clean air.

Useful for biogeography and environmental studies: helps answer questions on habitat suitability, distribution across biomes (e.g., tundra), and use of lichens as bioindicators of air quality and climate conditions.

📚 Reading List :
  • Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 4: Weathering, Mass Movement and Groundwater > CHEMICAL WEATHERING > p. 37
  • Science-Class VII . NCERT(Revised ed 2025) > Chapter 2: Exploring Substances: Acidic, Basic, and Neutral > HOLISTIC LENS > p. 10
  • Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 25: The Arctic or Polar Climate > Natural Vegetation > p. 235
🔗 Anchor: "Can lichens survive and grow on a surface without soil, such as on bare rock or ..."
📌 Adjacent topic to master
S3
👉 Biological weathering by mosses and lichens
💡 The insight

Mosses and lichens colonize bare rock and produce organic acids and humid microenvironments that chemically and physically alter the substrate.

High-yield for geography and ecology questions on weathering and soil genesis; links geomorphology with biology and explains early stages of landscape transformation. Knowing this helps answer questions on soil formation, rock decay, and roles of pioneer organisms.

📚 Reading List :
  • Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 4: Weathering, Mass Movement and Groundwater > CHEMICAL WEATHERING > p. 37
  • Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Biological Activity and Weathering > p. 91
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 5: Geomorphic Processes > Process of Soil Formation > p. 44
🔗 Anchor: "Can mosses survive and grow on a surface without soil, such as on bare rock or t..."
🌑 The Hidden Trap

Mycorrhizae. Since Lichens (Algae+Fungi symbiosis) were tested, the next logical sibling is Mycorrhizae (Fungi+Plant Root symbiosis), which is critical for phosphorus absorption in nutrient-poor soils.

⚡ Elimination Cheat Code

The 'Pioneer Pair' Heuristic. In Ecology textbooks, Lichens and Mosses are almost always mentioned together as the 'First Colonizers' of bare rock. If you see them in options, they are a functional unit. Ferns and Mushrooms require pre-existing organic matter (energy source), making them 'followers' rather than 'leaders' on truly barren surfaces.

🔗 Mains Connection

Pedogenesis (Soil Formation). These organisms are the biological architects of the earth's crust. Link this to Geography Mains (Soil Profile) -> without these pioneers, there is no regolith, no agriculture, and no food security.

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Which of the following are the most likely places to find the musk deer in its natural habitat ? 1. Askot Wildlife Sanctuary 2. Gangotri National Park 3. Kishanpur Wildlife Sanctuary 4. Manas National Park Select the correct answer using the code given below :

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Which of the following statements regarding soil is/are correct? 1. Alluvial soils are rich in nitrogen content. 2. Black soils are rich in iron and lime but deficient in nitrogen. 3. Laterite soils are rich in iron and aluminium but deficient in nitrogen and potassium. Select the correct answer using the code given below.