Question

In a lake ecosystem, the pyramid of biomass is generally
a. Spindle-shaped
b. Inverted
c. Upright
d. Horizontal

Answer 1

Hint: The pyramid of biomass shows how much biomass,i.e., the amount of living or organic matter present in organisms.

Complete Answer:
A pyramid of biomass depicts the relationship between biomass and trophic level. It is the total amount of living or organic matter in an ecosystem present in the unit area in different trophic levels. The pyramid of biomass can be inverted or upright depending upon the ecosystem.

- Option a: In a lake ecosystem, the pyramid of biomass is an inverted form. As we know that in the spindle-shaped pyramid, the number goes down at each succeeding level. Therefore, this option is incorrect.

- Option b: In the lake ecosystem, the pyramid of biomass is an inverted form. It is so because the producers in the aquatic system are tiny phytoplankton. These phytoplanktons grow and reproduce rapidly. Hence, the pyramid of biomass has a small base, with the consumer biomass exceeding the producer biomass. Hence, the pyramid takes inverted biomass. Therefore, this option is correct.

- Option c: The pyramid of biomass is inverted for e.g., in a grassland ecosystem, where the producer occupies the highest biomass, followed by the primary consumers. The primary consumers are followed by secondary consumers and then tertiary consumers. As the biomass is calculated by the biomass of organisms multiplied by the number of organisms present at each trophic level. Hence, the biomass of the producer is much more than the primary consumers and decreases further sequentially in secondary and tertiary consumers. Therefore, this option is incorrect.

- Option d: The pyramid of biomass cannot be horizontal as the biomass is calculated by the biomass of organisms multiplied by the number of organisms present at each trophic level. Therefore, this option is incorrect.

Thus, the correct option is b) inverted.

Note: The relationship between numbers, biomass, energy, or bio productivity of different trophic levels in an ecosystem is represented by a pyramid known as the ecological pyramid or Eltonian pyramid.