Question

Explain the following with suitable examples.

a. What type of changes occur in the amount of energy during its transfer from plants to apex consumers?

b. What are the differences between flow of matter and of energy in an ecosystem? Why?

Answer 1

a. The amount of energy reduces as we move from lower trophic levels to higher ones. Energy is lost as it gets transferred from one organism to another because energy is lost as metabolic heat when the organism of one trophic level consumes the organisms of another trophic level. This can also be explained on the basis of 10% rule which states that when energy is passed in an ecosystem from one trophic level to the next, only ten percent of the energy will be passed onto the next trophic level.

This can be explained with the help of energy pyramid in case of an aquatic ecosystem.



As, we move from lower trophic level to the higher trophic level, there is a decrease in the amount of energy which is transferred.


b. The major difference between flow of matter and of energy is that the flow of matter occurs in a cyclic manner i.e. it is recycled, however, the flow of energy in an ecosystem is unidirectional which means, it is not recycled. The flow of matter follows the following path-

• Decomposers release nutrients when they break down dead organisms.
• The nutrients are taken up by plants through their roots.
• The nutrients pass to primary consumers when they eat the plants.
• The nutrients pass to higher level consumers when they eat lower level consumers.
• When living things die, the cycle repeats.

In case of flow of energy, the energy flows through an ecosystem in one direction, from photosynthetic organisms to herbivores to omnivores and carnivores and decomposers, less and less energy becomes available to support life. This loss of useable energy occurs because each energy transfer results in the dissipation of some energy into the environment as heat.