M.1—Prefixes, units, symbols and standard form

Use SI units and prefixes consistently, convert scales such as kilo, milli, micro and nano, and interpret inequality or proportional symbols.

Write the unit with the number and use standard form for very large or small biological quantities.

2.5 µm is 2.5×10⁻⁶ m, not 2.5×10⁻³ m; the prefix determines the power of ten.

A correct numerical value with a mismatched unit is still an incorrect biological result.