Yes, it's possible!
Head over to your account, and find the survey that you want to edit.
In the Build tab, enable the Make this question required.
The required questions cannot be skipped. This ensures questions will never contain empty answers but might reduce the overall survey response rates.
Keep in mind that your customer is free to close the web page at any time without losing any answers they've already left, so there will still be instances that you'd receive survey responses without answers to the follow-up or additional questions.