Do you mean pre-germinated (sprouted) seeds?
The root appears first, so should be planted pointing downwards of course.
Bean seeds sprout from the scar along the middle. It's usually recommended to sow them vertically to reduce the risk of the seed rotting off - (runner bean seeds have a small dimple below the scar which should point downwards - French bean seeds probably do too but you'd need a microscope to see them!)
Doesn't really matter - they're pretty good at sorting themselves out.
The roots of squashes appear from the 'pointy end', so should be sown with the pointy end facing down.