Prokaryotes don't have a nuclear envelope they have no nucleus.
the layer in the earth I did it before
I believe it is they are reactants because they’re present before the reaction. O2 and glucose are reactants in the cellular respiration process. The product is ATP
Smaller molecules diffuse easily as compared to the larger molecules. In other words, smaller is the size of molecule, easier and faster is its diffusion across a semipermeable membrane.
Hope I helped