Yes 100%, because a lot of coins are traded against the value of Bitcoin itself, so if Bitcoin drops so do the altcoins!
Its being observed that most of the altcoins price does change as per the btc price movement. As the btc price increases so does the other altcoins keep up and vie versa. This I feel happen due to other coins were born after the bitcoin or due to bitcoin it resulted in other altcoin so invariably other coins is depended sort of on bitcoin price.
I think bitcoin was not control other altcoins, but almost all crypto currency value or prices was depending on bitcoin. Because as per observation when bitcoin value increasing up the value of altcoins is going down and when bitcoin going down the prices of all altcoins in the market was strength growing up. Maybe their price was affected each one but it does not means that bitcoin control altcoins.