The function of companion cells is

Trees may be damaged by animals which rub against them,wearing away a strip of bark right around the tree trunk and exposing the xylem. The tree will then

Which of the tissue is more important for the translocation of sucrose?

Who described the mass flow hypothesis?

The removal of a ring of bark from the trunk of a tree eventually kills it,since

Arrange the following events of mass flow of organic material in sequence:
$I$. Sugars are transported from cell to cell in the leaf
$II$. Food is synthesized in form of glucose by leaf cells
$III$. Movement of water takes place into sieve tube elements
$IV$. Downward movement of sugar occurs in the stem
$V$. Solutes are actively transported into the sieve elements