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

Step 1 : Understanding the Question:
Ecological pyramids are graphical representations designed to show the relationship between different trophic levels based on energy, biomass, or numerical population. While most are upright, some specific ecosystems produce "inverted" pyramids. We need to identify which parameter and ecosystem combination results in an inverted shape.
Step 2 : Key Formulas and Approach:
1. Pyramid of Energy: Always upright (due to the 10% law of energy transfer).
2. Pyramid of Number (Grassland): Typically upright (many plants support fewer animals).
3. Pyramid of Biomass (Grassland): Upright (the total weight of grass is more than the total weight of consumers).
4. Pyramid of Biomass (Aquatic/Sea): Often inverted due to the high turnover rate of tiny producers.
Step 3 : Detailed Explanation:

Energy Pyramids (D): These are never inverted. As energy is transferred from one trophic level to the next, a significant amount is lost as heat. Consequently, there is always more energy at the producer level than at any consumer level.

Grassland Pyramids (A and C): In a terrestrial grassland, a huge number of producers (with a massive total dry biomass) support a smaller number of primary consumers, who in turn support even fewer secondary consumers. Thus, the pyramids of number and biomass in grasslands are upright.

Marine/Sea Biomass Pyramids (B): In the sea, the primary producers are microscopic phytoplankton. While they produce a lot of food, their "standing crop" biomass at any single moment is quite small because they are consumed very rapidly by zooplankton. This small producer biomass supports a much larger biomass of zooplankton and fish. Because the base (producers) has less biomass than the higher levels (consumers), the pyramid is inverted.

Step 4 : Final Answer:
The pyramid of biomass in a marine or aquatic ecosystem is the standard example of an inverted pyramid in ecology. Thus, the correct option is (B).