Greetings Q Nefer tee tee - Gt Q and wife of Akhnaten [I think]
I think this is homework where you make an observation - mold and are invited to conclude things
That is - YOU are meant to conclude things
Cheese definitely isnt sterile ( it has its own bugs )
but the mold - must have come from your fingers and not the cheese
and it takes five days to grow and become visibile
I think
Oh and that cheese is a good growing medium for some things on yor fingers and not others ( coz they didnt grow )
The order of events is touch, transfer, germination possibly, growth and visibility