None at all.
You should do them, but it is possible to get 100% without having done anything.
The activities are sort of like revision quizzes that you take to make sure you understand the content.
There is that CV thing at the end, but time management can be demonstrated in other ways like completing assignments on time, coming to tutes/labs and making use of the tute/lab time effectively. These would be a better proof than just copying or guessing your way through the activities.
Then there's also teamwork and craftsmanship that you can easily BS along the way