Question

All of the statements are true for ecological pyramids except
A. Energy available at a lower trophic level is always more than that at a higher trophic level
B. The pyramid of numbers in a parasitic food chain is inverted
C. Pyramid of biomass in sea is upright normally
D, In a tree ecosystem, squirrels are primary consumers and ticks are secondary consumers

Answer 1

Hint:-Ecological pyramids are graphical representations that delineate the relationship between the trophic levels of an ecosystem. The pyramids can be of biomass, numbers or energy flow. Pyramids can be upright or inverted.

Complete step-by-step solution:-Ecosystem can be defined as a community where living organisms along with nonliving components interact with the environment. An ecosystem is divided into trophic levels. A typical ecosystem contains four trophic levels – primary producers, primary consumers, secondary consumers and decomposers. The relationship between each of these trophic levels can be represented in the form of a pyramid, called Ecological pyramids.
There three types of ecological pyramids – pyramid of biomass, pyramid of energy, pyramid of numbers. Except the pyramid of energy, which is generally upright, the two pyramids can be either upright or inverted.
Energy enters an ecosystem through the level of primary producers, that is green plants. The plants are capable of synthesizing their own food, hence the name producers. The green plant traps the solar energy from the sun. However, when they are eaten by herbivores, the amount of energy transferred is only 10 percent of the energy received from the sun. This is in line with the second law of thermodynamics, which states that when energy is converted into different forms, disorder increases in a system. For biological entities, energy is lost in respiration and as heat (generated from metabolism). Therefore, energy available at a lower trophic level is always more than that at a higher trophic level.

Fig 1: Pyramid of energy in an ecosystem

A parasite is a microorganism that lives within an animal and derives nutrition from them. A parasitic food chain is a type of food chain that shows the energy transfer from larger animals to smaller ones. For example, the primary producers are eaten by herbivores. These plants and the animals may be parasitized by microorganisms. However, unlike normal pyramids of numbers, the parasitic food pyramid is always inverted. This is because many parasites can live in the body of a host. Thus, the parasites outnumber the producer or consumer trophic levels. Therefore, we can say that the pyramid of numbers in a parasitic food chain is inverted.
The primary producers in a sea ecosystem are phytoplankton. The consumers are fishes. The number of phytoplankton is usually less, that is, the biomass of phytoplankton is less than that of biomass of fishes. Also, biomass in an ecosystem is largely dependent on the reproductive capability of organisms. The lifespan of phytoplankton is shorter than that of fishes. Therefore, we can state that the Pyramid of biomass in the sea is always inverted.

Fig: Inverted pyramid of biomass in a sea ecosystem

In a tree ecosystem, squirrels represent the primary consumer level, since they are herbivores. Ticks are arthropods that survive on the blood of animals, and thus they belong to the secondary consumer level. Therefore, we can say that in a tree ecosystem, squirrels are the primary consumers, while ticks are secondary consumers.

Therefore, option (c) is correct.

Note:- Ecological pyramids help us to study the relationship between trophic levels of any ecosystem. Ecological pyramids studies are of great importance to ecologists because these pyramids show the eating and being eaten relationships between individuals. They measure the efficiency of energy transfer of the ecosystem. The pyramids help ecologists to monitor an ecosystem and help them figure out the damages. If the damages to the ecosystem are known, it can be controlled or repaired.