Carbon dioxide, oxygen, water, and acids may all cause chemical weathering. Mechanical weathering is the process of breaking a large rock into smaller pieces without changing the minerals in the rock. Mechanical weathering may be caused by frost, ice, plant roots, running water, or heat from the sun.
I think it's the nucleus. Isn't the nucleus the brain of the cell?
Just look it up on the internet
The nucleus controls the activities within a eukaryotic cell
