Planar representation of a planar bipartite graph

Question

I can't understand the following :

In the planar representation of a planar bipartite graph ,each region is bordered by atleast 4-edge curves .

Kindly help me with this..

Answer 1

In an arbitrary planar graph, if we draw it in the plane, each face will be bordered by $\geq 3$ edges. In the bipartite case, however, it must be $\geq 4$ edges (a $3$-edge face is a triangle, which would contradict the graph being bipartite).