AP BIOLOGY

Detailed explanation-1: -During phloem transportation sugar is moved in form of sucrose in to the companion cells and them into the living phloem sieve tube cells by-

Detailed explanation-2: -The sugar in the form of sucrose is moved into the companion cells and then into the living phloem sieve tube cells by active transport. This creates a hypertonic condition in the phloem.

Detailed explanation-3: -The cotransport of a proton with sucrose allows movement of sucrose against its concentration gradient into the companion cells. occurs. From the companion cells, the sugar diffuses into the phloem sieve-tube elements through the plasmodesmata that link the companion cell to the sieve tube elements.

Detailed explanation-4: -The photosynthesis-produced sugars are transported vertically, horizontally, and laterally to all other organs, mostly through the phloem, in the form of sucrose. Disaccharide sugar sucrose is made up of the subunits of glucose and fructose.

Detailed explanation-5: -The sucrose is actively transported against its concentration gradient (a process requiring ATP) into the phloem cells using the electrochemical potential of the proton gradient. This is coupled to the uptake of sucrose with a carrier protein called the sucrose-H+ symporter.