Explain the following with suitable examples.

A. What type of changes occurs 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?

:A. Primary consumers (herbivores) eat green plants. They take energy into their bodies. The herbivores use this energy for movement and reproduction. Some parts of the plant which was eaten cannot be digested by the herbivore; the energy in these parts of the plant passes out of the herbivore's body as waste. Some of the energy is used for growth and remains as organic matter in the herbivore's body. It is this energy which can be eaten by the secondary consumer. Only about 10% of the energy which the plant used for growth is taken into the body of the secondary consumers (carnivores).

As the energy is passed along the food chain much of the energy is either used or lost and only 10% of the energy is transferred to the next level.

B. Energy flow in the ecosystem is directional and is only in one direction because Sun is the ultimate source of energy. Sun energy is fixed into plants and from plants to the different consumers. Thus, energy enters into an ecosystem as sunlight, part of the energy is retuned as heat and part is fixed as food (chemical compound) with help of inorganic materials. The chemical compounds are recycled in the ecosystem through different biogeochemical cycles. Therefore, in any ecosystem, energy from in one direction and materials are recycled.