Where the floor meets the wall!

I had to do some sheetrock work beneath my window and when I pulled the baseboard off I noticed that there were different size gaps in the flooring of the wood and I can feel cold air coming through different spots from underneath the house which is a crawl space.

I was wondering what could I do to fill these gaps. Should I try some type of caulk since the baseboard will cover up that part of the floor and nothing will be seen?

I definitely do not want to make many different cuts but I...

Where the floor meets the wall!