What is the smallest particle of any substance that has all the properties of that substance?

How energy flows through each level in this energy pyramid. is all the matter and energy from one level transferred to the next level?

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes

The backbone of the double helix has an alternating molecules. what do you call these alternating molecule?