Which of the following statements about the limitations of ecological pyramids is incorrect?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → They assume a simple food chain, something that is very common in nature.
Ecological pyramids are a simple way of showing number, biomass or energy at each trophic level, but they have limits. They ignore a species that belongs to two or more trophic levels, they assume a simple food chain and cannot show a food web, and they leave out saprophytes.
Option (1) They do not take into account the same species belonging to two or more trophic levels. — A correct statement. Pyramids do not take into account the same species belonging to two or more trophic levels.
Option (2) They assume a simple food chain, something that is very common in nature. — An incorrect statement. Pyramids assume a simple food chain, but such a chain almost never exists in nature; natural communities have food webs.
Option (3) Saprophytes are given no place in them, even though saprophytes play a vital role in the ecosystem. — A correct statement. Saprophytes are given no place in ecological pyramids, even though they play an important part in the ecosystem.
Option (4) They do not accommodate a food web. — A correct statement. Because they are built on a simple food chain, pyramids do not accommodate a food web.
NCERT Extract:
Ecological Pyramids – “However, there are certain limitations of ecological pyramids such as it does not take into account the same species belonging to two or more trophic levels. It assumes a simple food chain, something that almost never exists in nature; it does not accommodate a food web. Moreover, saprophytes are not given any place in ecological pyramids even though they play a vital role in the ecosystem.”