Question

Which is not a functional unit of an ecosystem
(a) Productivity
(b) Decomposition
(c) Energy Flow
(d) Stratification

Answer 1

Hint: Two types of this feature are seen, namely vertical and horizontal. It represents the distribution of different species at different levels or layers in a particular ecosystem. It is observed in oceans and forests. Factors like light penetration, temperature, etc influence this feature.

Complete answer:
Stratification is not a functional unit of an ecosystem. It is seen in different communities and is different for different types of habitat. For example stratification, horizontal stratification is seen in deep ponds and lakes, whereas vertical stratification is seen in oceans.
The ecosystem possesses a natural tendency to persist. This is made possible by a variety of functions performed by the structural components. The components of the ecosystem are seen to function as a unit to ensure its persistence.
The key functional aspects of the ecosystem are:
- Productivity
- Decomposition
- Energy Flow
- Nutrient cycling
Productivity: It is the rate of biomass production. Productivity in an ecosystem is of two types, primary and secondary productivity.
Decomposition: While productivity involves synthesis and building processes, decomposition is equally important which concerns the breakdown of complex organic matter to inorganic raw material like $C{O}_2$, $H_{2}O$ and various nutrients by decomposers. The major site of decomposition is the upper layer of the soil in the terrestrial habitat and bottom of water bodies.  Dead remains like leaves, bark, flowers, and dead remains of animals including fecal matter constitute detritus which is the staple for decomposition.
Energy flow: Energy flow is a sequential process of the moment of energy in an ecosystem through a series of organisms. Sun is the only source of energy for all ecosystems on earth (except for the deep- sea Hydrothermal ecosystem) .
Nutrient cycling: It is a sequence of living organisms which involves the transfer of food energy from the producer, through a series of organisms with repeated eating and being eaten is called the food chain.
So, the correct answer is, ‘Stratification.’

Note:
Stratification refers to the arrangement of vegetation in layers. Each layer is inhabited by different animal and plant communities. It is the vertical distribution of different species at different levels in an ecosystem. In a forest ecosystem, trees occupy the topmost layer, the shrubs occupy the next layer and herbs and grasses occupy the base layers.