Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

A bow wake is created when the wave source moves faster than the wave propagation speed.
What is created when the wave source moves faster than the wave propagation speed?

Diffusion process helps absorptive protists absorb food molecules across their cell membranes.
Which process helps absorptive protists absorb food molecules across their cell membranes?

Each hemisphere of the cerebrum divided into 4 lobes.

How many lobes is each hemisphere of the cerebrum divided into?