Select the mis-matched pair in the following and correct it.

A. Biomagnification — Accumulation of chemicals at the successive trophic levels of a food chain

B. Ecosystem — Biotic components of environment

C. Aquarium — A man-made ecosystem

D. Parasites — Organisms which obtain food from other living organisms

Suggest one word for each of the following statements/ definitions

(a) The physical and biological world where we live in

(b) Each level of food chain where transfer of energy takes place

(c) The physical factors like temperature, rainfall, wind and soil of an ecosystem

(d) Organisms which depend on the producers either directly or indirectly for food

Explain the role of decomposers in the environment?

We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why?

Indicate the flow of energy in an ecosystem. Why is it unidirectional? Justify.