Question

Pyramid of numbers in a grassland/tree ecosystem is
A)Always inverted
B)Always upright
C)Both A and B
D)Spindle shaped

Answer 1

Hint: The pyramid of numbers is a graphical representation that indicates at each trophic stage the number of species. It is an upright pyramid in view of the fact that producers are often more numerous than other trophic stages in an ecosystem.

Complete answer:
The numbers of producers, herbivores and carnivores at their successive trophic stages are seen by this Pyramid. This pyramid may be either vertical, or partly upright or twisted.

Grassland Ecosystem-
The number of producers (mainly grasses) in the grassland ecosystem is often the largest, followed by declining levels at the second trophic level (herbivores), the third trophic level (carnivores) and the lowest number of apex predators. A pyramid of numbers is therefore upright in the grassland.

Pond Ecosystem
The producers are phytoplankton such as algae, bacteria etc. in a pond environment. In number, they are the limit. The number of small herbivorous fish, rotifers, etc., is less than that of farmers, whereas the number of small carnivorous fishes is even lower. Finally, there is a smaller number of apex users or the largest carnivorous fishes. Thus in a Pond Ecosystem, the Pyramid of numbers is also upright.

Forest Ecosystem
The producers are large-sized trees that form the backbone of the Pyramid in a forest ecosystem. The main users are produced by herbivores such as fruit-eating birds, deer, elephants etc. and are fewer than primary producers. After that at each successive stage, the number goes down. Thus a pyramid of numbers is partly upright or spindle-shaped in a woodland biome.

Parasitic Food Chain
In the case of parasitic food chains, a single plant or animal may support multiple parasites, which could further sustain a greater number of hyperparasites. So in a parasitic food chain, the pyramid of numbers is reversed.

Note: Depending on the existence of the food chain in the individual biome, the numbers and biomass pyramids which are upright or twisted, while energy pyramids are often upright.