I once rescued my biology grade back in secondary school in Romania by knowing the definition of a cell.
“The cell is the structural and functional unit of living things” I wrote. I wasn’t far off was I?
So yes, the cell is the unit of life. It’s a delimited volume where the chemistry of life can happen. In unicellular organisms, the cell is themselves, the body, the whole, the organism.
You will need to know about the difference between light, transmission electron and scanning electron microscopes – LM, TEM and SEM. Both the latter (as the name suggests) use a beam of electrons, rather than light, to produce an image of the sample.
TEM uses electrons which pass through the sample, so the resulting micrograph (image) shows everything within the sample in black and white, for example organelles in a cell. SEM uses electrons which scan the sample in 3D, resulting in a coloured micrograph with 3D detail, but no components from…