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

Eyespots do the cells in the front of a volvox typically develop to help swim towards light.
What do the cells in the front of a volvox typically develop to help swim towards light?

Surface tension is responsible for the fact that small insects can walk on water.
Surface tension is responsible for the fact that small insects can do this on water?

Birds live and breed on seven of the continents.

On how many of the continents do birds live and breed?