The show-me-tell-me questions check that you understand basic vehicle safety. They are not designed to catch you out, but they do expect you to know how to check things like lights, tyres, brakes, demisters, and warning lights.
A good approach is to practise the questions with the actual car you learn in. That way the controls, switches, dashboard symbols, and bonnet checks are familiar before test day.
During the practical test, answer calmly and keep driving safely if you are asked a show-me question on the move. The question matters, but control and observation still matter more.