AP BIOLOGY

Detailed explanation-1: -A micron or micrometer is a unit of measurement; it is denoted by µm. Micron is a smaller unit of measurement to measure the size of cells. As cells are very minute structures that cannot be seen through naked eyes, these are measured in microns or micrometers.

Detailed explanation-2: -The best unit to measure most cells is the micrometre, symbol m. For some sub-cellular structures, for instance ribosomes, or organisms such as viruses, it’s best to use a smaller unit – the nanometre, symbol nm.

Detailed explanation-3: -Cells can vary between 1 micrometer (m) and hundreds of micrometers in diameter. Within a cell, a DNA double helix is approximately 10 nanometers (nm) wide, whereas the cellular organelle called a nucleus that encloses this DNA can be approximately 1000 times bigger (about 10 m).

Detailed explanation-4: -Cell size can be measured using an eyepiece graticule . The graticule has a scale ruled on it. You must find out the distance measured for each division of the graticule. You can then use the graticule to measure cells.