Question

Given below is an imaginary pyramid of numbers. What could be one of the possibilities about certain organisms at some of the different levels?

• A. Level one PP is "pipal trees" and the level SC is "sheep"
• B. Level PC is "rats" and level SC is "cats"
• C. Level PC is "insects" and level SC is "small insectivorous birds"
• D. Level PP is " Phytoplanktons" in sea and "Whale" on top-level TC

Answer 1

The correct option is C Level PC is "insects" and level SC is "small insectivorous birds"

The given figure shows spindle-shaped pyramid in a single tree ecosystem. Here, a single, large sized tree provides food to a large number of herbivores, which in turn support a few carnivores and the later are eaten up by a small number of top carnivores.
So here PP is used for primary producers and i.e the single tree.
Let us consider the first statement - Level one PP is "pipal trees" and the level SC is "sheep"
Sheep eat grass, clover, forbs, and other pasture plants. Sheep are very selective in their grazing habits. And sheep do not feed on pipal trees. Option A is not the correct option.
Let us consider the second statement - Level PC is "rats" and level SC is "cats". Here the 50 cats prey on 500 rats. Even though this statement also looks like the correct statement, it is not. Because 500 rats cannot have a single tree as the primary source of food. This will lead to the decline of the tree ecosystem. Hence option B is not the correct option.
Let us consider the third statement - Level PC is "insects" and level SC is "small insectivorous birds". Here the primary consumers are insects which are 500 in number. And the secondary consumers which feed on the insects are small insectivorous birds which are 50 in number. This explanation fits the graph in the question. So here the PP is used for primary producer .i.e. single tree, PC is primary consumers .i.e a large number of insects, SC is secondary consumers, i.e. small insectivorous birds and TC is top consumers, which may be eagles or falcons, etc. So the correct option is C
We have arrived at the correct option but an explanation as to why the last option is wrong.
Let us consider the fourth statement - Level PP is "phytoplankton" in sea and "Whale" on top-level TC. When we consider the pyramid of numbers for the aquatic ecosystem the producers/phytoplankton are always huge in number. So the PP in the graph represented by phytoplankton is 1 is not correct.