The difference in these sentence?
The function of the knife from sentence 1 is only to cut apples?

1) Do you have a knife to cut the apple with?

2) Do you have a knife to cut the apple?

Question

The difference in these sentence? 
The function of the knife from sentence 1 is only to cut apples?

1) Do you have a knife to cut the apple with?

2) Do you have a knife to cut the apple?

Answer

The two sentences have identical meanings. 'With' is optional but not essential. Both mean the speaker wants a knife because they need to cut an apple. Any knife will do. There is no suggestion it must be a knife specifically designed for cutting apples.

Answer

no, in 1) the speaker just specifies the action, not limits the function of the knife

Non perdere l'opportunità di imparare una lingua comodamente da casa tua. Esplora la nostra selezione di insegnanti di lingue esperti e iscriviti subito alla tua prima lezione!