Question

Which of the following ecological pyramids is generally inverted?
A) Pyramid of numbers
B) pyramid of energy
C) pyramid of biomass in a forest
D) pyramid of biomass in a sea

Answer 1

We know that the ecological pyramid of biomass becomes inverted when the mass of producers in an ecosystem is less than the successive consumers. An ecological pyramid shows the relationship between various living things at various trophic levels within the food chain. It also shows the relationship between biomass and various trophic levels.

Complete answer:
An ecological pyramid is a graphical representation of a food chain depicting the interrelationships between different types of organisms, which occupies different trophic levels based on their feeding habits. In a typical ecological pyramid, the base is occupied by the producers, followed by primary consumers, secondary consumers, tertiary consumers and top carnivores. The ecological pyramid has the disadvantage that they do not provide an appropriate representation of decomposers. There are three types of pyramids; the pyramid of energy, the pyramid of numbers and the pyramid of biomass.
1. Pyramid of energy shows the flow of energy in the ecosystem. It is always upright because energy is lost at each trophic level in the form of heat.
2. Pyramid of numbers that depicts the number of an organism at each trophic level. Generally, the producers are the largest in numbers, followed by the gradual decrease in the number of consumers. Therefore, it is upright. A somewhat inverted pyramid of numbers is seen when a tree is a producer and is supporting a number of organisms.
3. Pyramid of biomass shows the relation between organisms occupying the different trophic levels based on their biomass. So, if in a given ecosystem the producers have high biomass, the pyramid of biomass will be upright, and if the producers have low biomass it becomes inverted. Therefore, in an aquatic ecosystem, the pyramid of biomass is generally inverted.
Thus, the correct answer is option D.

Note: An inverted pyramid of biomass is seen in oceans and aquatic ecosystems where producers are the phytoplanktons. Their number is quite large but their biomass is less than zooplanktons. The biomass of producers in the desert and rainforest is way to more than the consumers, so they show an upright pyramid of biomass.