Give the functions of companion cells.

(N/A) $1$. Companion cells are specialized parenchymatous cells that are closely associated with sieve tube elements.
$2$. They maintain the pressure gradient in the sieve tube elements,which is essential for the translocation of food (sugars) through the phloem.
$3$. They provide metabolic support to the sieve tube elements,as sieve tube elements lack a nucleus and other organelles at maturity.
$4$. The sieve tube elements and companion cells are connected by pit fields present between their common longitudinal walls,facilitating the exchange of materials.