Answer:
They went from atoms to oxygen molecule.
Explanation:
I'm not sure if this is the answer your teacher is looking for, but in simple terms you had 2 oxygen atoms. Together they make an oxygen molecule, which is the stuff we breathe.
Can't say i can answer this. :/
The answer is Big Mac size
Hetero means different. Examples could be heterogenous (different in form) or heterozygous (having two different forms of a gene).