Will BH3-THF reduce the ketone? It will reduce an acid - so if you cleave 1-ethylcyclopentene with permanaganate instead of ozone to get the ketone and acid, you can then reduce the acid with BH3-THF and make the alcohol. The mechanism of reduction is complex, but it works for acids but not esters or ketones or aldehydes. (While you can't reduce a ketone by itself with BH3, I am not certain that if you have both a ketone and an acid that reduction will be selective - the triacetoxyborane that rolnor suggests is a lot like the intermediate in the acid reduction.)
But I think they teach it at the sophomore level as being selective for acids.