Yes of course Bitcoin price is very influential on the price Altcoins, when the price Increase in Altcoin Bitcoin prices will also rise, and vice versa and even worse.
On the relationship to the dollar, yes, uniquely affects. When Bitcoin grows, everything grows automatically against the dollar. But in relation to Bitcoin, not always the altcoins follow Bitcoin. The more experienced I think this is understandable, but beginners are often confused in these concepts when making transactions