Question

Which one of the following statements is wrong regarding ecological pyramids?

• A. They do not include saprophytes (decomposers)
• B. Insect feeding on a big tree is an example of inverted pyramid of numbers
• C. The pyramid of biomass in a sea is inverted
• D. They consider the same species belonging to two or more trophic levels

Answer 1

The Correct Option is D

Let's evaluate each statement regarding ecological pyramids:

(1) They do not include saprophytes (decomposers): This is correct. Ecological pyramids typically represent trophic levels based on producers, primary consumers, secondary consumers, etc., but decomposers (saprophytes) are generally not included in the pyramid. They play an important role in breaking down dead organic material, but are not typically counted in these pyramids.

(2) Insect feeding on a big tree is an example of an inverted pyramid of numbers: This is correct. In some ecosystems, especially in cases where a few large organisms (like trees) support many smaller organisms (like insects), the pyramid of numbers can be inverted. The number of insects would exceed the number of trees, making the pyramid appear upside down.

(3) The pyramid of biomass in a sea is inverted: This is correct. In marine ecosystems, especially in the case of phytoplankton and zooplankton, the biomass pyramid can be inverted. Phytoplankton have a very short lifespan and small biomass, but they are consumed rapidly by larger zooplankton, leading to more biomass in consumers than producers.

(4) They consider the same species belonging to two or more trophic levels: This is incorrect. Ecological pyramids generally do not consider the same species at multiple trophic levels. Each trophic level represents different species or groups of organisms that fulfill different roles in the food chain. A single species should belong to only one trophic level in a pyramid.

Thus, the wrong statement is (4) They consider the same species belonging to two or more trophic levels.

The correct answer is (4).

Answer 2

Ecological pyramids typically represent each species at a single trophic level based on their primary role, so statement (4) is incorrect. This model does not account for organisms occupying multiple trophic levels, maintaining a simplified representation.