Can humans be considered carbon sinks? If so, for how long? What living organisms are better long-term sinks than humans?

Humans can be considered carbon sinks - yes, for a lifetime.

living organisms are better long-term sinks than humans - plants or trees.

Carbon sinkanything that absorbs more carbon from the atmosphere than it releasesit is the opposite of a carbon source as a carbon source is anything that releases more carbon than it absorbsHumans release carbon mainly by respiration, however, absorbs very less amount as foodPlants grab carbon dioxide from the atmosphere to use in photosynthesis and only some of this carbon is released to the soil when plants die and decompose

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Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.