CBSE Class 12 Biology — Ecosystem

In an ecosystem, different species occupy different levels and vertical distribution of species is found. This is called _________.

Assertion (A) : In terrestrial ecosystem much larger fraction of energy flows through grazing food chain. Reason (R) : Grazing food chain may be connected to Detritus food chain at some levels.

(a) Given below is a pyramid found in an ecosystem, where each bar represents the standing crop available in the trophic level. [Diagram: an inverted ecological pyramid – a wide upper bar labelled 'PC' resting on a narrower lower bar labelled 'PP'.] (i) Identify the kind of pyramid and with the help of an example explain the conditions where this kind of pyramid is possible in nature. [1] (ii) Write any two limitations of ecological pyramids. [1] OR (b) In an ecosystem there was loss of biodiversity due to some project in that area. (i) How will biodiversity be affected? (2 points) [1] (ii) List two major causes of loss of biodiversity. [1]