What allows simple transformers to step voltage up or down?

Its as a result of unequal coiling of wires.
A transformer has two separate windings i.e primary and secondary. The Ratio of primary coils to secondary coils (turn ratio Np/Ns) is the one which makes it a step down or step up transformer. Step up transformer increases the voltage while step down transformers reduce it.

Telophase colchicine is a chemical obtained from plants that prevents the assembly of spindle fibers