What is the cell organelle that forms the outer boundary of a cell and allows certain materials to move into and out of a cell?

What is the cell organelle that is a gel-like material inside the cell that contains water and nutrients?

What is the cell organelle that directs the activity of a cell that contains chromosomes with DNA?

What is the cell organelle that separates the nucleus from the cytoplasm?

What is the cell organelle that breaks down food and releases energy to the cell?