what at natural science interviews at Cambridge like?

There's a ton of videos on YouTube from Colleges about this and studytubers discussing their interviews.

Expect questions to come from different directions with some Maths and Chemistry as well as Biological questions.

For Biology questions they may well start on something familiar then very quickly pull you into deep territory that you've never seen before to see how you'll cope with new ideas and concepts.

It is typical that no student will correctly answer every one of these problems, the good ones may get 70-80% there with some assistance.