grammar - Starting a sentence with "One question..." and then stating the question?

I am wondering about proper grammar in this case. Or if I should just avoid starting a sentence with "One question..." (my gut tells me I should).

Here are some examples:

One question you could research is, do female birds mature more quickly than their male counterparts?

I believe it is proper to end with a question mark there, and I put the comma because I also believe that is correct grammatically. Although I feel perhaps a colon would be more suitable?

and another example:

One question you could research, and whose answer I am particularly interested in myself, is: Do female birds mature more quickly than their male counterparts?

In this second example I am particularly interested in whether I should have a colon after "is", or if a comma (or nothing) would be better?

So to restate my questions: I am wondering whether the examples are correct, or if there are any suggestions/corrections regarding them. Additionally, is starting a sentence with "One question..." is okay, or should I avoid doing so for some reason?

Thanks.

Bonus Example: (I am okay if what follows is ignored/not answered, but I don't think it warrants an additional question so I'm asking it here).

Consider the following:

One question you could research is: what impact does doing ten jumping jacks a day have on a person's lifespan?

vs

One question you could research is what impact doing ten jumping jacks a day has on a person's lifespan.

I don't know if the second formulation is correct or not. If it isn't, why is it incorrect? If it is correct, why do I not need a comma or a question mark at the end? Did I reformulate the question as an indirect question? (I'm not clear on the distinction between direct and indirect question yet, sorry).

Answer

With your first set of examples, either are correct. I believe It is quite reasonable construction. I think you're struggling in that the first part of the sentence sets up an indirect question:

One question you could research is whether female birds mature faster than their male counterparts.

As for the punctuation, this is a style issue. Either of your constructions would fit with The Chicago Manual of Style

In your bonus example, you are stating an indirect question so the punctuation is correct in the latter case.

One question you could research is what impact doing ten jumping jacks a day has on lifespan.

Still this is confused by using what because typically what is a direct question word. You're better off rewriting in this case:

One question you could research is the impact of doing ten jumping jacks a day on lifespan.