What organisms are always at the start of any food chains

Sunlight

Explanation:

I don't know how to explain it but I'm gonna try

Food chain

Sunlight is the most crucial thing in a food change because without it producers will not be cable to produce photosynthesis which is a proces in which producers use sunlight light to produce ATP (energy).And if producers are not able to do photosynthesis the herbivores will not be able to eat and eventually died the same thing happens whit the carnivore they will not have anything to eat and eventually dies.

the way that the mass of carbon can be conserved through cellular respiration is through a process/law called the law of conservation of mass which even tho it undergoes a process, mass is not be destroyed or changed