The concept of "Active mass flow in which oxygen is required" was proposed by:

During translocation of food,at the sink end (root cells),the sugar is used and excess water . . . . . . .

Which of the following is responsible for changing the direction of the source and sink in plants?

Phloem loading is related to:

"Girdling Experiment" was performed by plant physiologists to identify the plant tissue through which:

Consider the following statements and choose the correct option from the codes given below:
$I.$ Loading of phloem is related to the increase of sugar in phloem.
$II.$ Active loading of sugar in the sieve tube of phloem is driven by a proton pump.
$III.$ Pressure may be positive or negative in sieve tube cells.
$IV.$ Water and solutes move through the sieve tube against the pressure gradient.
$V.$ Cytoplasmic strands pass through the holes in sieve plates and form continuous filaments.