I haven't seen the paper! We are not allowed at my school until tomorrow.
But if CF came up, it wouldn't be about the genetics etc. There was a question on a specimen paper about celiacs and I think it will be along the same lines.
So basically, CF will stop nutrients being absorbed easily into the small intestine therefore reducing glucose and amino acids going into blood. This will reduce growth etc.
Like is said. Not seen paper. But I literally did the celiacs question this morning with my yr11 so hoping it's similar.
As for the carrots. Yes it seems funny, but surely it's just an osmosis question?
Every year the kids come out and say 'you didn't teach us that' but it's all about putting what has been taught to an unusual situation.
Hope all your DC are busy revising for the chem now! 
