discuss the prophecies of act 5 scene 1

The prophecies are actually fulfilled through Act 5. The witches work in riddles more than anything else. Birnam Wood literally looks like it is moving towards the castle as the soldiers cut down the very small trees and use them to "shadow their numbers". Macduff is leading the charge into the castle. He has a huge score to settle with Macbeth. Macduff finally kills Macbeth because he was cut out of his mother's womb when he was a baby. Elizabethan's felt that this birth was technically a perversion of nature hence he was not born of woman.