Question

Which Pyramid is always upright?

• A. energy
• B. Biomas
• C. Number
• D. All

Hint:

The "10% Law" of energy transfer in ecosystems dictates that only about 10% of the energy from one trophic level is transferred to the next, with the rest lost. This fundamental principle ensures that the pyramid of energy will always be upright.

Answer 1

The Correct Option is A

Step 1: Understand Ecological Pyramids
Ecological pyramids are graphical representations that show the relationship between different trophic levels in an ecosystem. They typically represent biomass, energy, or numbers of organisms at each successive trophic level. Step 2: Analyze the nature of each type of pyramid

Pyramid of Energy: This pyramid represents the flow of energy from one trophic level to the next. According to the laws of thermodynamics, energy is lost at each transfer (typically about 90% is lost as heat), meaning less energy is available at successive trophic levels. Thus, the pyramid of energy always tapers upwards, making it always upright. It can never be inverted because energy transfer is always unidirectional and always involves a loss.
Pyramid of Biomass: This pyramid represents the total mass of living organisms at each trophic level. While often upright (e.g., in terrestrial ecosystems where producers have the largest biomass), it can be inverted in certain ecosystems, such as aquatic ecosystems. For example, in a pond, the biomass of phytoplankton (producers) might be less than the biomass of the zooplankton (primary consumers) that feed on them at a given time, due to the rapid turnover rate of phytoplankton.
Pyramid of Number: This pyramid represents the number of individual organisms at each trophic level. It can be inverted or spindle-shaped. For instance, a large tree (producer) might support many herbivores (primary consumers) like insects, leading to an inverted pyramid of numbers. Similarly, one producer might support numerous parasites, leading to an inverted pyramid. Step 3: Evaluate the options based on the analysis (A) Energy
As explained, due to the unidirectional flow and loss of energy at each trophic level, the pyramid of energy is always upright. (B) Biomass
The pyramid of biomass can be inverted, especially in aquatic ecosystems. (C) Number
The pyramid of number can be inverted (e.g., a single tree supporting many insects) or spindle-shaped. (D) All
This option is incorrect because pyramids of biomass and number can be inverted. Step 4: Conclusion
The only ecological pyramid that is always upright, reflecting the fundamental law of energy flow in ecosystems, is the pyramid of energy. The correct answer is: $$(A) energy$$