Question

In an open ocean, the biomass of primary producers (microscope algae) is often lower than the biomass of higher trophic levels (zooplanktons and fish), as illustrated by an inverted pyramid of biomass. How can there be enough food in an open ocean to support the higher trophic levels?
A. Microscopic primary producers are source of food of high quality
B. Microscopic primary producers have high rate of growth and reproduction
C. The microscopic primary producers are less abundant
D. The higher trophic levels are cold blooded animals which do not require much food.

Answer 1

Hint:- Biomass is defined as the total dry matter (dry weight) present in an ecosystem at any time. Biomass can be measured graphically. This graph shows the shape of a pyramid known as a biomass pyramid. This pyramid shows the total mass of an organism and gives a rough idea of ​​the overall impact of food chain relationships for an entire ecological group. Served as a low standard dish. For example, the number of some herbivorous insects will increase if more plant food is available.

Complete Answer:- Ecological pyramids- It is a schematic representation of the relationships between different trophic levels in terms of energy, biomass and number of organisms. The base of each pyramid represents the producer or first trophic level. The pinnacle represents the tertiary or upper level users. In general, all pyramids are straight, but there are a few exceptions.
There are basically three types of pyramids these are
A. Pyramid of number
B. Pyramid of biomass
C. Pyramid of Energy
The biomass of diatoms and other phytoplankton in pond or lake ecosystems is less important compared to crustaceans and small herbivorous fish that feed on these producers. The biomass of large predatory fish living in small fish is much higher. In fact, this is the state of most aquatic ecosystems, including the sea.
In an open ocean, the biomass of primary producers (microscope algae) is often lower than the biomass of higher trophic levels (zooplanktons and fish) but phytoplankton or microscopic algae have very high rate of growth and reproduction their life span is very short and they rapidly Complete their life cycle and new population groups or cultures of phytoplankton form every hour Thus, the cumulative energy content captured by these generations in the year after phytoplankton was created is certainly much higher than that captured by only a few generations of herbivorous fish in the relevant time and space.

So, the correct option is (B).

Note:- - In the forest ecosystem an upright pyramid of biomass is present . The tree biomass is of course very high than the biomass of many birds that eat trees. Likewise, the biomass of avian parasites in very large numbers is less than that of birds. Therefore , biomass decreases with successive trophic levels in an upright pyramid.
- Limitations of ecological pyramids
1. It must not consider the same species belonging to two or more trophic levels.
2. It adopts simple food chains which almost never exist in nature. however, it has no place in the ecological pyramid; They play an important role