Answer:
a. chemical changes and flow of energy
Explanation:
Energy flow from one organisms of one tropic level to other, matter cycling and transformation of energy are the functions that sustain the ecosystem. Transformation of solar energy into chemical energy by plants serves as energy source for all heterotrophic living beings in the system. The heterotrophic organisms digest the ingested food (chemical change) to release energy to support their life processes. The energy stored at one tropic level is carried to next tropic level via food chain and food webs and represents the interaction between living components of ecosystem.
