What are scientific questions based on?

A scientific question is just a question or idea that a scientist, or essentially anybody has that can be answered in a scientific manner with experiments and observations. Obviously most scientists choose to research fields of study they are interested in.

Some general questions like "how does a person think" would be far too complex for a single experiment.

So a scientist will try to think of what kinds of questions their tools could answer. And, potentially inventing new tools to help answer the questions. One tries to select questions with well defined parameters, so one can actually come up with a valid answer or explanation that is supported by data. So rather than asking how a person thinks, one might look at the components of a brain. So a better question might be to ask what the basic functional unit of the brain is.

One then can use tools like a microscope, staining, cell recording, and etc to describe a neuron with its dendrites, axon, synapses, and etc. Then perhaps look at slug brains to determine how the neurons actually work.

Finally with multiple questions, experiments, and even many scientists one might be able to build a description of the structure and function of the brain.