Question

Ecological pyramid
I) based on the flow of energy is always upright.
II) has producers always occupying the base of the pyramid.
III) are visual representations of energy flow, biomass accumulation and number of individuals at different trophic levels.
IV) based on number, can be upright, inverted or kind of lumpy, depending on the ecosystem.

Choose the correct statements from the above.

• A. I and II only
• B. I, II and III only
• C. II and III only
• D. I, II, III and IV

Answer 1

The correct option is D I, II, III and IV

Ecological pyramids are visual representations of the relationship between individuals, with the producers forming the base and top carnivores at the tip. On the basis of accumulated biomass, the direction of the energy flow and the number of individuals, they are further categorised into three general types-

1. pyramid of numbers
2. pyramid of biomass
3. pyramid of energy

Producers occupy the base of the pyramid. They trap the solar energy and convert this into chemical energy by the process of photosynthesis. This energy is then passed on from one organism to another in a food chain. Basically, other than the producers, all the other trophic levels are consumers because they feed upon the food that the producers produce.

Different types of pyramid deal with different entities, like for example, the pyramid of numbers deals with the number of organisms in each trophic level. Pyramid of number is mostly upright, where the number of producers is highest and the number of consumers in other levels of pyramids keeps on decreasing. But, inverted pyramid of numbers is also seen in the case of parasitic ecosystems; where a single tree in the forest has a large number of birds on it which in turn have a large number of parasitic insects in their body, which overall makes the pyramid upside down or inverted. The nature of the pyramid of numbers varies depending on the ecosystem.