Final answer:
The original source of energy in a food chain is the sun, which is converted into chemical energy by plants through photosynthesis.
Step-by-step explanation:
The original source of energy in a food chain is the sun. Plants, through the process of photosynthesis, convert the sun's energy into chemical energy in the form of glucose. This energy is then passed on to herbivores (plant-eating animals) when they consume the plants, and subsequently to carnivores (meat-eating animals) when they consume the herbivores. Decomposers, such as bacteria and fungi, also play a role in breaking down dead organisms and returning nutrients back to the environment.
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