Question

Select the incorrect options from the given statements.
(i) Pyramids of energy and yearly biomass production can never be inverted, since this would violate the laws of thermodynamics.
(ii) Pyramids of standing crop and numbers can be inverted, since the number of organisms at a time does not indicate the amount of energy flowing through the system.
(iii) There are certain limitations of ecological pyramids such as they do not take into account the same species belonging to two or more tropic levels.
(iv) Saprophytes are not given any place in ecological pyramids even though they play a vital role in the ecosystem. : '

• A. (i) and (ii)
• B. (iii) and (iv)
• C. (ii) and (iii)
• D. None of these

Answer 1

Answer: (D)

The ecological pyramid is a graphical representation of an ecological parameter such as biomass, energy, or the number of individuals present at various trophic levels of a food chain. Ecological pyramids are also called as Eltonian pyramid. They have certain limitations:

1. It does not take into account the same species belonging to two or more trophic levels, for example, insectivorous plants.
2. It assumes a simple food chain and does not accommodate a food web.
3. Saprophytes, decomposers, microbes, and detritivores are not given any place in ecological pyramids.

The second law of thermodynamics states that whenever energy is transformed, there is a loss of energy through the release of heat. This occurs when the 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 complete process. Additional loss of the energy occurs during respiration and movement. Hence, more and more energy is lost as one moves up through the trophic levels. If this pyramid is inverted, it would violate the law of thermodynamics. Hence, the pyramid can never be inverted.
Pyramid of numbers is a graphical representation of a number of individuals present per unit area at different trophic levels.
In the parasitic food chain, at each successive trophic level, the number of the organisms is higher than in the preceding one, and the size decreases gradually at a successive level. Thus, the shape of the pyramid may be inverted of standing crop and numbers.