Test: Ecological Pyramids (NCERT) - NEET MCQ

Given pyramid is pyramid of numbers in a parasitic food chain. In a parasitic food chain, the pyramid of numbers is inverted. This is due to the fact that a single plant may support the growth of many herbivores and each herbivore in turn may provide nutrition to several parasites, which in turn support many hyper-parasites. Thus, from the producer towards consumers, the number of organisms gradually increase, making the pyramid inverted in shape.

Pyramids of biomass are comparatively more fundamental, as they, instead of geometric factor, show the quantitative relationships of the standing crops. In grassland and forest, there is generally a gradual decrease in biomass of organisms at successive levels from the producers to the top carnivores. Thus, pyramids of biomass and number are upright in terrestrial ecosystems.

Pyramid of numbers in a forest ecosystem is spindle shaped. In a forest ecosystem, number of producers is lesser but supports a greater number of herbivores. Which in turn support a fewer number of carnivores. This results in spindle shaped structure of pyramid of numbers.

In a marine aquatic ecosystem, the biomass of phytoplanktons (producers) is smaller than that of zooplanktons (primary consumers) and the biomass of zooplanktons is smaller than that of secondary consumers. This results in the inverted pyramid of biomass in an aquatic ecosystem. This shape is the consequence of the very short life spans of phytoplanktons, which are consumed almost as rapidly as they are formed. Also phytoplanktons have high reproductive potential, i.e., they reproduce rapidly.

Pyramid of biomass for terrestrial ecosystems (grasslands, forests) the biomass generally decreases at each higher trophic level from plants via herbivores to carnivores. This is evident from the fact that the terrestrial producers’ viz. grasses, trees and shrubs have a much higher biomass than the animals that consume them, such as deer, zebras and insects. A single plant or animal in a parasitic food chain may support numerous parasites, which might be further supporting a larger number of hyperparasites. Thus, the pyramid of numbers in a parasitic food chain is inverted.
So the correct option is 'the pyramid of biomass is upright in a grassland ecosystem and the pyramid of number is upright in a parasitic food chain'.

The given pyramid represents pyramid of biomass in an aquatic ecosystem. In this pyramid, biomass of phytoplanktons, i.e., producers (represented by A) is smaller than that of zooplanktons, i.e., primary consumers (represented by B). Phytoplanktons support zooplanktons as the latter feed upon them.

In an open ocean, the large numbers of phytoplankton quickly complete their life cycles and sets of new population or crops of phytoplankton are formed every few hours or days. Thus, the cumulative energy contents that these generation after generation of phytoplankton trap in course of a year is certainly much more than trapped by only a few generations of herbivorous fishes in the corresponding time and space. The energy content trapped by the carnivores living on the herbivorous fishes is the leat.

Mr. X eating curd / yoghurt should be considered as occupying third trophic level. Producers or greeen plants (first trophic level) are consumed by herbivore (second trophic level). And from them curd, yoghurt (made from dairy breed) is consumed by third trophic level like man.

When the biomass of producer is less and that of the consumer is more the pyramid will have an inverted shape. It occurs in a pond and lake ecosystem. Here the biomass of diatoms in planktons is negligible as compared to their date of crustaceans and small fishes. inverted pyramid soil found in that ecosystem where the number and biomass of producers of more and those of consumers are less.
In most of the ecosystems, the number of the biomass of producers is more than those of a consumer is less. This type of ecosystem has a pyramid where the apex is pointed upwards. This type of pyramid is known as upright pyramid.
In some ecosystem, the number of the producers is more than the consumers. The apex is pointed upwards. This is known as the upright pyramid of the number. Found in the grassland ecosystem.

The second law of thermodynamics states that whenever energy is transformed, there is a loss energy through the release of heat. This occurs when energy is transferred between trophic levels as illustrated in a food web. When one animal feeds off another, there is a loss of heat (energy) in the process. Additional loss of energy occurs during respiration and movement. Hence, more and more energy is lost as one moves up through trophic levels. If this pyramid is inverterved, it would violate the law of thermodynamics. Hence the pyramid can never be inverted.
The pyramid of numbers depicts the relationship in terms of the number of producers, herbivores and the carnivores at their successive trophic levels. There is a decrease in the number of individuals from the lower to the higher trophic levels. The number pyramid varies from ecosystem to ecosystem. Since the amount if energy flowing through the system is not indicated, the pyramid can be inverted.
These are the diagrammatic illustrations of connection between different trophic levels in terms of energy, biomass and number of an organism. The base of each pyramid represents the producers or the first trophic level. Apex represents tertiary or top level consumers. If any species belongs to two or more trophic level, it can causes differences and issues in energy flow and numbers. 
Saprophytes are organisms which feed on dead and decaying matter and these pyramid exhibit interaction between the living components and decomposers interact with dead organisms at all level. This makes it difficult to place it in the ecological pyramid. Hence, they are not given any place in ecological pyramids even though they play a vital role in the ecosystem.
So the correct option is 'none of these'.