Ecology

1. Ecotone is a

Ecotone is a

diversified ecosystem
transitional ecosystem
transparent ecosystem
stagnation ecosystem
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The correct answer is B) transitional ecosystem.
An ecotone is defined as a transition zone between two different ecological communities or ecosystems. It contains species characteristic of both bordering ecosystems, and often includes species not found in either.
Ecotones are important ecologically as they often have higher biodiversity (edge effect) than the adjacent ecosystems due to the presence of species from both communities. Examples include the transition between a forest and a grassland, or a riverbank bordering a terrestrial area.

2. Which one of the following is known as the life-supporting zone of the

Which one of the following is known as the life-supporting zone of the Earth ?

Ecosystem
Biosphere
Atmosphere
Biome
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The biosphere is the sum of all ecosystems on Earth. It is the narrow layer of the Earth where life exists, encompassing parts of the land (lithosphere), water (hydrosphere), and air (atmosphere).
The biosphere is essentially the life-supporting zone of the Earth because it is the region where living organisms interact with the physical environment.
An ecosystem is a community of living organisms interacting with each other and their physical environment in a specific area. The atmosphere is the layer of gases surrounding the Earth. A biome is a large area characterized by its climate and the plant and animal communities adapted to that climate (e.g., forest, desert, grassland). While these are all components related to the Earth and its life, the biosphere is the overarching term for the entire zone where life is found.

3. The organic component of soil, formed by the decomposition of leaves a

The organic component of soil, formed by the decomposition of leaves and other plant materials that adds to the fertility of the soil is called :

Humus.
Top soil.
B-horizon.
Mineralization.
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Humus is the stable organic component of soil that results from the decomposition of dead plant and animal matter by microorganisms.
Humus is dark in color, rich in nutrients essential for plant growth, and significantly improves soil structure, water retention, and aeration. It is a key indicator of soil fertility.
Top soil (A-horizon) is the uppermost layer of soil, typically the richest in organic matter (including humus) and biological activity. B-horizon (subsoil) is below the topsoil and generally contains less organic matter but may accumulate minerals leached from the A-horizon. Mineralization is a process of decomposition where organic matter is broken down into inorganic substances, releasing nutrients, but it refers to the process, not the organic component itself.

4. The idea of Ecological Succession was first formally coined by

The idea of Ecological Succession was first formally coined by

Charles Darwin.
Clements.
Sir A. Tansley.
Emberlin.
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The correct answer is Clements.
Frederic Clements is widely credited with formulating the first comprehensive theory of ecological succession in the early 20th century. He developed the concept of succession as a directional process leading to a stable climax community, influenced by climate. His monograph “Plant Succession: An Analysis of the Development of Vegetation” (1916) was foundational in this field.

A) Charles Darwin’s work focused on evolution by natural selection, not specifically ecological succession.
C) Sir A. Tansley coined the term “ecosystem” but is not primarily credited with coining the idea of ecological succession itself, although he contributed to ecological thought.
D) Emberlin is not a figure widely recognized for coining the initial formal idea of ecological succession compared to Clements.

Clements’ monoclimax theory of succession was later challenged by other ecologists like Henry Gleason (individualistic concept) and Robert Whittaker (polyclimax theory), who proposed more complex and less deterministic views of vegetation change. However, Clements’ work laid the groundwork for the formal study of ecological succession.

5. Which one of the following shows a unique relationship with an insect

Which one of the following shows a unique relationship with an insect that has coevolved with it and that is the only insect that can pollinate this tree ?

Fig
Mahua
Sandalwood
Silk cotton
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The fig tree (genus *Ficus*) exhibits a unique and highly coevolved symbiotic relationship with specific fig wasps (family Agaonidae). Each species of fig tree is typically pollinated by only one or a few specific species of fig wasp, and the fig wasp relies entirely on the fig tree for reproduction. The female wasp enters the fig (which is an inverted flower structure called a syconium) to lay eggs and pollinate the flowers inside, while the male wasps are wingless and live and die within the fig.
– The fig-fig wasp relationship is a classic example of obligate mutualism and coevolution.
– This relationship is highly specific, with a particular fig species depending on a particular wasp species for pollination, and the wasp depending on that fig species for reproduction.
Mahua (Madhuca longifolia) is primarily pollinated by bats and other nocturnal visitors, but also receives pollination from insects. Sandalwood (Santalum album) pollination is less well-documented but involves insects and potentially wind. Silk cotton (Bombax ceiba) is primarily pollinated by birds (like mynas and crows) and bats. None of these exhibit the kind of highly specific, obligate one-to-one coevolutionary relationship seen between figs and fig wasps.

6. Consider the following statements : Statement-I : The soil in tropical

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 to decompose quickly.
Which one of the following is correct in respect of the above statements?

Both Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement-I
Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I
Statement-I is correct but Statement-II is incorrect
Statement-I is incorrect but Statement-II is correct
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The correct answer is D) Statement-I is incorrect but Statement-II is correct.
Statement I is incorrect. Soils in tropical rainforests are typically poor in nutrients. The high rainfall leads to rapid leaching of minerals, and the high temperatures and humidity cause very rapid decomposition of organic matter. Nutrients are quickly taken up by the dense vegetation and are stored primarily in the biomass, rather than accumulating in the soil. When the vegetation is cleared, the soil quickly loses its fertility.
Statement II is correct. High temperatures and abundant moisture create ideal conditions for microorganisms (bacteria, fungi) to decompose dead organic matter (leaves, wood, dead animals) very quickly. This rapid decomposition prevents the build-up of a thick layer of nutrient-rich humus in the soil.
The rapid decomposition and nutrient uptake by plants create a fast nutrient cycling system in tropical rainforests. While the biomass is rich in nutrients, the underlying soil is often nutrient-poor and acidic, contrasting sharply with soils in temperate forests where decomposition is slower, allowing for nutrient accumulation in the soil.

7. “Biorock technology” is talked about in which one of the following sit

“Biorock technology” is talked about in which one of the following situations ?

Restoration of damaged coral reefs
Development of building materials using plant residues
Identification of areas for exploration/extraction of shale gas
Providing salt licks for wild animals in forests/protected areas
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“Biorock technology” is talked about in the context of the restoration of damaged coral reefs.
– Biorock technology, also known as Mineral Accretion Technology or Seament, is a process that uses a low-voltage electrical current passed through submerged metallic structures in seawater.
– This process causes minerals naturally dissolved in seawater (like calcium carbonate) to precipitate onto the structure, forming a hard layer similar in composition to natural reef rock.
– Corals transplanted onto these structures grow significantly faster and are more resilient to stress factors like high temperatures and pollution, aiding in reef restoration.
– Options B, C, and D relate to completely different fields (building materials, energy exploration, wildlife management).
The technology was invented by architect Wolf Hilbertz and biophysicist Thomas Goreau. It is considered a promising technique for accelerating the growth and survival of corals and other marine organisms, particularly in degraded reef environments.

8. “If rainforests and tropical forests are the lungs of the Earth, then

“If rainforests and tropical forests are the lungs of the Earth, then surely wetlands function as its kidneys.” Which one of the following functions of wetlands best reflects the above statement ?

The water cycle in wetlands involves surface runoff, subsoil percolation and evaporation.
Algae form the nutrient base upon which fish, crustaceans, molluscs, birds, reptiles and mammals thrive.
Wetlands play a vital role in maintaining sedimentation balance and soil stabilization.
Aquatic plants absorb heavy metals and excess nutrients.
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The correct option is D. The analogy “wetlands function as its kidneys” best reflects the function where aquatic plants absorb heavy metals and excess nutrients.
The kidney’s primary function is to filter waste products from the blood. Wetlands act similarly by filtering pollutants, sediments, and excess nutrients (like nitrogen and phosphorus from runoff) from water as it flows through them. This purification process prevents these substances from entering larger water bodies. The absorption of heavy metals and excess nutrients by aquatic plants and microbial action within the wetland are key mechanisms for this filtering and purification function.
Other vital functions of wetlands include groundwater recharge, flood control, shoreline stabilization, and providing habitat for diverse species. However, the filtering of water is the function most directly analogous to the function of kidneys in the human body.

9. “Leaf litter decomposes faster than in any other biome and as a result

“Leaf litter decomposes faster than in any other biome and as a result the soil surface is often almost bare. Apart from trees, the vegetation is largely composed of plant forms that reach up into the canopy vicariously, by climbing the trees or growing as epiphytes, rooted on the upper branches of trees.” This is the most likely description of

coniferous forest
dry deciduous forest
mangrove forest
tropical rain forest
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The description perfectly matches the characteristics of a tropical rainforest. Fast leaf litter decomposition occurs due to the high temperatures and humidity, leading to rapid nutrient cycling and often a thin or almost bare soil surface layer of organic matter. The dense canopy in tropical rainforests limits light penetration to the forest floor, leading to intense competition for light. This favors plant forms that can reach the canopy by climbing (lianas) or growing on other plants (epiphytes) to access sunlight. These features are not characteristic of coniferous forests (slow decomposition in cold climates), dry deciduous forests (decomposition limited during dry season, fewer epiphytes/climbers), or mangrove forests (unique adaptations to saline, waterlogged conditions).
– High temperature and humidity in tropical rainforests lead to rapid decomposition.
– Rapid decomposition results in nutrients being quickly absorbed by plants, leaving limited organic matter on the soil surface.
– Light competition in the dense canopy drives the evolution of climbers and epiphytes as prominent plant forms.
Tropical rainforests are characterized by high biodiversity, high rainfall, and warm temperatures throughout the year. The rapid nutrient cycling means that much of the ecosystem’s nutrients are stored in the biomass of the plants rather than in the soil itself. Disturbances like deforestation can lead to rapid soil degradation as nutrients are washed away or lost.

10. The vegetation of savannah consists of grassland with scattered small

The vegetation of savannah consists of grassland with scattered small trees, but extensive areas have no trees. The forest development in such areas is generally kept in check by one or more or a combination of some conditions.
Which of the following are such conditions?

  • 1. Burrowing animals and termites
  • 2. Fire
  • 3. Grazing herbivores
  • 4. Seasonal rainfall
  • 5. Soil properties

Select the correct answer using the code given below.

1 and 2
4 and 5
2, 3 and 4
1, 3 and 5
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The correct answer is C) 2, 3 and 4.
– Savannas are characterized by grasslands with scattered trees due to factors that limit dense forest growth.
– Fire (2) is a major factor, as seasonal dry periods make savannas prone to fires that kill young trees and favor fire-resistant grasses.
– Grazing herbivores (3) consume young trees and shrubs, preventing them from establishing and growing into mature trees.
– Seasonal rainfall (4), particularly the prolonged dry season, creates water stress that limits tree growth and increases fire frequency, contributing to the maintenance of the savanna structure.
– Burrowing animals and termites (1) can affect soil and vegetation locally but are not typically considered the primary factors controlling forest development across extensive savanna areas.
– Soil properties (5) can influence vegetation, but fire, grazing, and climate (seasonal rainfall patterns) are generally regarded as the dominant factors preventing savanna from transitioning into forest.
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