Which one of the following ecological pyramids is always upright?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Pyramid of energy
An ecological pyramid shows the producers at the base and each higher trophic level above them. There are three kinds: the pyramid of number, of biomass and of energy. Only the pyramid of energy can never be inverted. At every step some energy is lost as heat, so each trophic level always has less energy than the level below it.
(1) Pyramid of number — Incorrect. It can be inverted. One big tree can support a very large number of insects.
(2) Pyramid of biomass — Incorrect. It is inverted in the sea, where the biomass of fishes is far more than that of the phytoplankton.
(3) Pyramid of energy — Correct. Energy falls at every trophic level, so this pyramid is always upright.
(4) Pyramid of forest ecosystem — Incorrect. This is not a kind of pyramid. A forest has all three pyramids, and its pyramid of number is not upright.
NCERT Extract:
Ecological Pyramids – …
