Question

Ecological pyramids represent the relationship between the organisms at different trophic levels and they are generally inverted for :

• A. Pyramid of biomass in grassland
• B. Pyramid of biomass in sea
• C. Pyramid of number in grassland
• D. Pyramid of energy in pond ecosystem

Hint:

Logic Tip: The marine biomass pyramid is the classic "exception to the rule." Tiny, fast-breeding phytoplankton support massive, long-living whales. Low biomass base $\rightarrow$ High biomass top = Inverted Pyramid.

Answer 1

The Correct Option is B

Concept:
Ecological pyramids visually represent the structure of an ecosystem across trophic levels (producers, primary consumers, secondary consumers, etc.). Depending on the ecosystem and the parameter measured (number, biomass, or energy), these pyramids can be upright, inverted, or spindle-shaped.
Step 1:
The pyramid of energy is always upright, regardless of the ecosystem. According to the 10% law, energy is always lost as heat at each transfer to the next higher trophic level. It can never be inverted. This immediately eliminates Option (4).
Step 2:
In a grassland:
• Pyramid of Number: There are millions of grasses (producers) supporting fewer herbivores (like deer or insects), which support even fewer carnivores. This pyramid is upright. This eliminates Option (3).
• Pyramid of Biomass: The total dry weight of all the grasses vastly exceeds the total weight of the herbivores, which exceeds the weight of the carnivores. This pyramid is also upright. This eliminates Option (1).
Step 3:
In marine or aquatic ecosystems (like a sea or ocean), the primary producers are tiny phytoplankton. They have very rapid reproduction and turnover rates. At any given moment, their standing crop (biomass) is very small. However, this small standing crop of phytoplankton supports a much larger standing crop of zooplankton, which in turn supports an even larger biomass of small fishes, and finally, huge biomasses of large fishes or whales.
Step 4:
Because the biomass at the producer level is significantly smaller than the biomass at the primary consumer level, the resulting pyramid shape is inverted (narrow base, wider top).
Step 5:
The pyramid of biomass in an aquatic environment like the sea is a classic example of an inverted pyramid. Thus, Option (2) is correct.