Which of the following is made up of dead cells?

Phellem is made up of dead cells. Phellem also called cork. The cork is impervious to water due to deposition of suberin.

Collenchyma is living mechanical tissue.

Phloem is a conducting tissue. It consist of living sieve tube cells, companion cells and phloem parenchyma and dead phloem fibre.

 Xylem parenchyma is the only living constituent of xylem.