Set 8 | Important Ecology MCQs

Correct Answer is B.

• Winds blowing across the ocean’s surface push water away, causing water from below to rise and replace it. This phenomenon is known as “upwelling.” The water that surfaces during upwelling is usually colder and rich in nutrients.
• These nutrients nourish the surface waters, often resulting in high biological productivity. As a result, areas with frequent upwelling tend to be rich fishing grounds.

Correct Answer is D.

• Eco-sensitive zones are designated under the Environment (Protection) Act, 1986, which makes the first statement incorrect.
• Prohibited activities in these zones include tourism activities such as flying over protected areas in aircraft or hot air balloons, and the discharge of effluents or solid waste into natural water bodies or land areas.
• Regulated activities include felling of trees, establishment of hotels and resorts, commercial use of natural water, installation of electrical cables, drastic changes in agricultural practices (e.g., the use of heavy technology or pesticides), and road widening.
• Permitted activities include ongoing agricultural and horticultural practices by local communities, rainwater harvesting, organic farming, adoption of green technologies, and the use of renewable energy sources.
• Therefore, statement 2 is also incorrect, making option (d) the correct answer.

Correct Answer is D.

• All organisms in an ecosystem are interconnected, and changes in the population of one species can impact the entire ecosystem. For example, if foxes in a food chain were removed, the rabbit population would increase due to the absence of a natural predator. Thus, option A is incorrect.
• Humans significantly affect the environment through activities such as overpopulation, pollution, burning fossil fuels, and deforestation. These actions have led to climate change, soil erosion, poor air quality, and contaminated water sources. Therefore, R is correct.

Correct Answer is C.

• time. In grasslands, past fires have cleared away trees, altering the composition of the ground. Without trees to stabilize the soil, water erodes much of it, leaving the exposed ground as the pioneer population, which is eventually replaced by grass.
• However, grass absorbs most of the water before it can reach the roots of shrubs, preventing further ecological succession beyond the grass stage.

Correct Answer is B.

• The concept of ‘Ecological Transition’ was first introduced by John W. Bennett in his book “The Ecological Transition: Cultural Anthropology and Human Adaptation.” Ecological transition refers to the development of an anthropocentric (human-centered) perspective toward the natural world, a mindset that emerged during the Western Renaissance and has since influenced various civilizations and nations.
• Ecologically, this transition is reflected in the increasing integration of nature into human culture and the decline of local self-sufficiency—meaning that local communities are less able to meet their needs using the resources available within their specific geographic area.

Correct Answer is B.

• The entire sequence of communities that progressively change and replace one another in a particular area during ecological succession is called a “Sere.”
• Each stage within this sequence is known as a “seral stage,” and the final, stable community that forms is called the “climax community.”

Correct Answer is A.

A scientist named Eugene Odum described biotic succession as a sequenced process, which occurs in the following order:

1. Nudation: This is the formation of a bare area uninhabited by organisms, typically caused by disturbances such as soil erosion, wind action, storms, fires, or human activities. These disturbances can be topographic, climatic, or biotic in nature.
2. Migration or Invasion: This step involves the arrival of seeds, spores, or other reproductive propagules that facilitate the establishment of species. Invasive species, which are non-native organisms, can spread widely due to high reproductive rates and efficient dispersal mechanisms.
3. Ecesis: Also known as “colonization,” this stage refers to the initial establishment of a plant community. It depends on soil structure, and in this phase, early colonizing species proliferate through germination, growth, and reproduction. Ecesis results from allogenic mechanisms, and the pioneer species survive and spread during this phase.
4. Reaction: As species occupy the habitat, they modify the environmental conditions, which in turn leads to the displacement and replacement of some species by others.
5. Stabilization: This is the final stage where the climax community is established. A climax community is stable, mature, self-sustaining, and adapted to the region’s conditions. The physical and chemical environment is stabilized, supporting the entire community, which persists until another disturbance occurs.

Correct Answer is C.

The correct order of biological organization, from the organism to the biosphere, is as follows:

1. Organism: An individual living being.
2. Population: A group of individuals of the same species living in a specific area, capable of reproducing with each other.
3. Community: Populations of two or more species living in the same geographical area and time period.
4. Ecosystem: A community of living organisms interacting with each other and their abiotic (non-living) environment, such as water, air, and soil.
5. Biome: A large ecological area characterized by similar climatic conditions, and containing multiple ecosystems.
6. Biosphere: The global sum of all ecosystems, including all living organisms and the physical environments (lithosphere, hydrosphere, atmosphere) they interact with.

Each level builds on the previous one, expanding the scope of interaction from individual organisms to the global ecosystem.

Correct Answer is C.

• Autotrophs, such as green plants, are the primary producers as they produce organic material by converting sunlight into energy through photosynthesis. They form the base of the food chain.
• Heterotrophs, like herbivores, are consumers, not producers. Herbivores are classified as primary consumers because they feed directly on the primary producers (plants). Secondary consumers, in turn, feed on herbivores. Therefore, herbivores are not secondary producers, but rather primary consumers.

Correct Answer is C.

• The correct sequence of ecosystems in order of decreasing productivity is: Mangroves, Grasslands, Lakes, and Oceans.
• Mangroves are highly productive ecosystems, followed by grasslands, then lakes. Despite covering around 70% of Earth’s surface, oceans have relatively low productivity, contributing only about 55 billion tons.
• This lower productivity is due to the limited availability of nutrients in many oceanic regions, compared to nutrient-rich ecosystems like mangroves and grasslands.