"Tap" doesn't go to drop down menu and check boxes?

Is there a way to have my tap button move to the drop down menu or the check box in the browser? It's really annoying when you're typing away and then you have to go do something on the drop down menu and the tap doesn't take you there.

Hold Option as you Tab through the webpage for more functionality ... also use the up/down arrows/Return

In System Preferences go to Keyboard & Mouse > Keyboard Shortcuts, under "Full Keyboard Access" check "all controls".