Activate or Deactivate a cell

Hello

I am trying to make a spreadsheet with an option of activated cells. Say, if I select YES in A1 cell (which is limited by YES and NO with data validation), the B1 will be activated to enter data. But I select the NO option, the B1 cell will remain deactivated and data cannot be entered into the B1 cell.

Can anyone please suggest a less complicated way ?