Ecology

Choose the Correct Answer

Correct Answer : Option a

Explanation
The pyramid of numbers represents the number of individuals at each trophic level in an ecosystem. An inverted pyramid of numbers occurs when a single producer (like a large tree) supports a much larger number of primary consumers (herbivorous insects).

However, the pyramid of energy always remains upright because energy flow in an ecosystem follows the laws of thermodynamics. Energy is lost as heat at each trophic level, making it impossible for higher trophic levels to have more energy than the lower ones.

Scenario (a) is correct: A single tree (producer) supports many herbivorous insects (primary consumers). These insects, in turn, are eaten by fewer carnivorous birds (secondary consumers). This results in an inverted pyramid of numbers (a few producers, many primary consumers, and fewer secondary consumers). However, the pyramid of energy remains upright because energy transfer follows the 10% rule only a small fraction of energy is passed on to the next trophic level.
Other incorrect options:

● Scenario (b): A vast number of phytoplankton → zooplankton → small fish. This represents a typical upright pyramid of numbers, not an inverted one.
● Scenario (c): Grass → herbivorous mammals → top predators. The number of producers (grass) is large, making the pyramid of numbers upright.
● Scenario (d): Herbivores feeding on multiple small plants → diverse carnivores. This scenario suggests a complex food web rather than an inverted pyramid of numbers.

Scenarios (b) and (c) depict upright pyramids of numbers, while scenario (d) does not accurately represent typical ecological relationships.