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

(b) Each level of the food chain where the 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

Solution –

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

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

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

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