Ecology imbalance MCQs with Explanations

Correct Answer: (C) Water limits and fire

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Ecological succession is the gradual process by which ecosystems change and develop over time. In grassland, trees have already been cleared away due to fires in the past, which also changes the ground composition. Without the trees to hold them, water washes away most of the soil and the underlying ground becomes the pioneer population, which is then replaced by grass. The grass, however, absorbs most of the water before it reaches the roots of the shrubs. Thus, the ecological succession does not occur beyond the grass.

Correct Answer: (B) Bennett

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The concept of ‘Ecological Transition’ was first used by John W. Bennett. He proposed the concept in his book ‘‘The Ecological Transition : Cultural Anthropology and Human Adaptation’’. "Ecological transition “ mean, the development of an anthropocentric orientation toward the natural world that emerged in the Western Renaissance but has since characterized every civilization and nation. Ecologically speaking, the transition is expressed in the growing incorporation of Nature into Culture and by the breakdown of local self-sufficiency the ability of the local group to satisfy its needs with existing resources in a particular geographical range.

Correct Answer: (A) Nudation, Migration, Ecesis, Reaction, Stabilization

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F. Element studied different species of plants and gave a generally agreed upon definition in 1916. According to him, biotic succession is a natural process of displacement of one particular community by another in a particular area. A scientist named Odum described it as a sequenced process. The correct order of biotic succession is as follows:
Nudation → Migration → Ecesis → Reaction → Stabilization
1. Nudation: It is the development of a bare site uninhabited by any organisms. The process is usually caused by disturbances. These factors can be either topographic (soil erosion, wind action etc); climatic (hails, storm, glaciations, fire etc.); or biotic (human activities).
2. Invasion or migration: The process of invasion or migration helps the arrival of seeds, spores or other reproductive propagules for establishment of species. Invasive species are non native organisms which can spread widely in a community. high reproductive rates and better dispersal mechanisms.
3. Ecesis: This is the initial establishment of plant community. This is dependent on the soil structure. The stage is also called as 'colonization'. In this stage, the early colonizing species proliferate abundantly through germination, growth, and reproduction. Ecesis is due to allogenic mechanisms alone. This is the stage at which the pioneer species survive the dispersal mechanisms.
4. Reaction: The environmental conditions get modified by the action of species occupying the habitat. These changes subsequently trigger the displacement and replacement of one species by another.
5. Stabilization is the process by which the climax community gets established. A climax community is mature, self-sustaining, stable and is the final stage of succession. The physical and chemical conditions are altered and stabilized to such levels that it supports the entire community. The climax communities are best adapted to the regions of succession and the community structure is likely to continue until another disturbance steps in.

Correct Answer: (C) Both 1 and 2

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Ecological balance is a stable balance in the numbers of each species in an ecosystem.
Ecological balance is also known as ‘The balance of nature’.
Ecological balance is defined as "a state of dynamic equilibrium within a community of organisms in which genetic, species and ecosystem diversity remain relatively stable, subject to gradual changes through natural succession."

Correct Answer: (D) All of the above

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