Question

An inverted pyramid of number and an inverted pyramid of biomass are respectively seen in
A. Grassland ecosystem
B. Sea and tree ecosystem
C. Tree and sea ecosystem
D. Sea and grass ecosystem
E. Tree and grassland ecosystem

Answer 1

Hint: In a pyramid of number, the total number of organisms at each trophic level is taken into account. In a biomass pyramid, the organic matter present at different trophic levels in an ecosystem is represented.

Complete answer:
An ecological pyramid is a visual depiction of the relationship between various species in the environment. The relationship is expressed in terms of number, biomass or energy. The producers represent the base of each pyramid while the top represents the tertiary or top-level consumer. The common ecological pyramids are the pyramid of numbers, the pyramid of biomass and the pyramid of energy.
The number pyramid indicates the cumulative number of individual species at each stage of the food chain of the ecosystem. An inverted pyramid of numbers can be seen in an ecosystem where the population includes a few very big biomass suppliers that benefit a greater number of smaller consumers. Thus, the number pyramid in the tree ecosystem will be inverted as the first trophic level, that is, the tree, is the least in number in the ecosystem.

The biomass pyramid reflects the overall living biomass or organic matter found at various trophic levels in the ecosystem.The biomass pyramid in the sea is therefore usually inverted since the population of fish at the higher level much exceeds that of phytoplankton.

Thus, the correct answer is option C i.e., C. Tree and sea ecosystem.

Note:In most ecosystems, all pyramids of number, energy and biomass are upright. This means that the organisms at the lower level are greater in number and biomass than those at the higher levels. The energy at a lower trophic level is also usually greater than those at a higher level.