An example of passive transport is osmosis. It is the only transport that doesn't require ATP to move something.
Enzymes acts as a catalyst in chemical reactions to speed up the rate of reaction.
Enzymes are not necessarily needed because substrates can disintegrate on their own, but enzymes are helpful to aid this process.
Electrons (negatively charged subatomic particles)
A) a large group of cells that grew without regulation.
A tumor is where there is a mutation that causes cells to lose their ability to self regulate, so they reproduce too fast and become unspecialised, causing a tumour.
Let me know if you have any questions