Observe the diagram and answer the question.
Identify the correct option with respect to figure 'Y' (trophic level = Number of individuals)
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → B = 21, A = 04
Figure Y is the inverted pyramid of biomass in the sea: a small standing crop of phytoplankton (A, about 4) supports a larger standing crop of zooplankton (B, about 21).
Option (2) B = 21, A = 04 — Correct. Figure Y is a pyramid of numbers. Reading the number of individuals at each trophic level from the figure gives B = 21 and A = 4, the values in the correct option.
NCERT Extract:
Ecological Pyramids – “… In most ecosystems, all the pyramids, of number, of energy and biomass are upright, i.e., producers are more in number and biomass than the herbivores, and herbivores are more in number and biomass than the carnivores. Also energy at a lower trophic level is always more than at a higher level. There are exceptions to this generalisation: … The pyramid of biomass in sea is generally inverted because the biomass of fishes far exceeds that of phytoplankton.”