A small standing crop of phytoplankton supports a large standing crop of zooplankton. This can be correctly represented by:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Inverted pyramid of biomass
A standing crop is the amount of living matter (biomass) present at a trophic level at one time. In the sea, a small standing crop of phytoplankton feeds a large standing crop of zooplankton and fish. The phytoplankton grow and are eaten very fast, so their biomass at any moment is small. A pyramid drawn from biomass is therefore narrow at the base: it is inverted.
Option (1) Inverted pyramid of energy — Incorrect. The energy pyramid can never be inverted, because energy is lost as heat at every step.
Option (2) Inverted pyramid of biomass — Correct. The producers’ biomass is smaller than the consumers’, so the base is the narrowest bar.
Option (3) Upright pyramid of biomass — Incorrect. An upright biomass pyramid would need more producer biomass than consumer biomass, which is the reverse of this case.
Option (4) Sometimes upright and sometimes inverted pyramid of energy — Incorrect. The pyramid of energy is always upright, never inverted.
NCERT Extract:
Ecological Pyramids – …
